Add support for polymorphism models#1894

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Add support for polymorphism models #1894

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61d6676
Add metaclass support for SQLAlchemy polymorphic models (joined-table…
ng-viet-hung Apr 28, 2026
c2851b2
Fix inherited relationship resolution in polymorphic subclass constru…
ng-viet-hung Apr 28, 2026
98c63d4
Add test suite for polymorphic inheritance
ng-viet-hung Apr 28, 2026
ff38e5c
Fix formatting
ng-viet-hung May 4, 2026
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105 changes: 102 additions & 3 deletions sqlmodel/_compat.py
View file
Open in desktop
Original file line numberDiff line numberDiff line change
@@ -1,13 +1,14 @@
import sys
import types
from collections.abc import Generator
from collections.abc import Generator, Iterable
from contextlib import contextmanager
from contextvars import ContextVar
from dataclasses import dataclass
from typing import (
TYPE_CHECKING,
Annotated,
Any,
ClassVar,
ForwardRef,
TypeAlias,
TypeVar,
Expand All@@ -26,6 +27,8 @@
from pydantic.fields import FieldInfo
from pydantic_core import PydanticUndefined as Undefined
from pydantic_core import PydanticUndefinedType as PydanticUndefinedType
from sqlalchemy import inspect
from sqlalchemy.orm import Mapper

BaseConfig = ConfigDict
UndefinedType = PydanticUndefinedType
Expand DownExpand Up@@ -68,6 +71,100 @@ def _is_union_type(t: Any) -> bool:
finish_init: ContextVar[bool] = ContextVar("finish_init", default=True)


def set_polymorphic_default_value(
self_instance: _TSQLModel,
values: dict[str, Any],
) -> bool:
"""By default, when init a model, pydantic will set the polymorphic_on
value to field default value. But when inherit a model, the polymorphic_on
should be set to polymorphic_identity value by default."""
cls = type(self_instance)
mapper = inspect(cls)
ret = False
if isinstance(mapper, Mapper):
polymorphic_on = mapper.polymorphic_on
if polymorphic_on is not None:
polymorphic_property = mapper.get_property_by_column(polymorphic_on)
field_info = get_model_fields(cls).get(polymorphic_property.key)
if field_info:
v = values.get(polymorphic_property.key)
if mapper.inherits or v is None:
setattr(
self_instance,
polymorphic_property.key,
mapper.polymorphic_identity,
)
ret = True
return ret


def _wrap_inherited_relationships_as_classvar(
base: type,
base_annotations: dict[str, Any],
dict_used: dict[str, Any],
) -> None:
"""Convert inherited relationship annotations to ClassVar on the subclass.

Pydantic would try to treat inherited SQLAlchemy relationship descriptors as plain
fields, which fails at class-creation time. Tagging them ClassVar tells
Pydantic to ignore them while SQLAlchemy continues to own the attribute.
"""
if not hasattr(base, "__sqlmodel_relationships__"):
return
for k in base.__sqlmodel_relationships__:
anno = base_annotations.get(k, Any)
if get_origin(anno) is not ClassVar:
dict_used["__annotations__"][k] = ClassVar[anno] # type: ignore[valid-type]


def _is_polymorphic_subclass(bases: tuple[type, ...]) -> bool:
"""Return True when any base class already defines a ``__tablename__``.

This distinguishes a polymorphic subclass (which inherits from an existing
table model) from a root table model that defines its own table.
"""
return any(
issubclass(base, BaseModel) and hasattr(base, "__tablename__") for base in bases
)


def _collect_inherited_namespace(
bases: tuple[type, ...],
dict_used: dict[str, Any],
) -> dict[str, Any]:
"""Merge base-class fields/annotations into *dict_used* for polymorphic subclasses.

Walks bases in method resolution order (reversed so the most-specific base wins),
collecting Pydantic field definitions and annotations from every
SQLModel table parent, and marking inherited relationships as ClassVar
so Pydantic ignores them.
"""
base_fields: dict[str, Any] = {}
base_annotations: dict[str, Any] = {}
for base in bases[::-1]:
if not issubclass(base, BaseModel):
continue
base_model_fields = get_model_fields(base)
base_fields.update(base_model_fields)
for k in base_model_fields:
if k in base.__annotations__:
base_annotations[k] = base.__annotations__[k]
_wrap_inherited_relationships_as_classvar(base, base_annotations, dict_used)
base_annotations.update(dict_used["__annotations__"])
dict_used["__annotations__"] = base_annotations
base_fields.update(dict_used)
return base_fields


def _relationship_keys(instance: _TSQLModel) -> Iterable[str]:
mapper = inspect(type(instance), raiseerr=False)
return (
mapper.relationships.keys()
if mapper is not None
else instance.__sqlmodel_relationships__
)


@contextmanager
def partial_init() -> Generator[None, None, None]:
token = finish_init.set(False)
Expand DownExpand Up@@ -265,11 +362,13 @@ def sqlmodel_table_construct(
object.__setattr__(self_instance, "__pydantic_private__", None)
# SQLModel override, set relationships
# Get and set any relationship objects
for key in self_instance.__sqlmodel_relationships__:
for key in _relationship_keys(self_instance):
value = values.get(key, Undefined)
if value is not Undefined:
setattr(self_instance, key, value)
# End SQLModel override
# Override polymorphic_on default value
set_polymorphic_default_value(self_instance, values)
return self_instance


Expand DownExpand Up@@ -319,7 +418,7 @@ def sqlmodel_validate(
object.__setattr__(new_obj, "__pydantic_fields_set__", fields_set)
# Get and set any relationship objects
if is_table_model_class(cls):
for key in new_obj.__sqlmodel_relationships__:
for key in _relationship_keys(new_obj):
value = getattr(use_obj, key, Undefined)
if value is not Undefined:
setattr(new_obj, key, value)
Expand Down
58 changes: 45 additions & 13 deletions sqlmodel/main.py
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -3,6 +3,7 @@
import builtins
import ipaddress
import uuid
import warnings
from collections.abc import Callable, Mapping, Sequence, Set
from dataclasses import dataclass
from datetime import date, datetime, time, timedelta
Expand DownExpand Up@@ -38,9 +39,10 @@
)
from sqlalchemy import Enum as sa_Enum
from sqlalchemy.orm import (
InstrumentedAttribute,
Mapped,
MappedColumn,
RelationshipProperty,
declared_attr,
registry,
relationship,
)
Expand All@@ -59,6 +61,8 @@
SQLModelConfig,
Undefined,
UndefinedType,
_collect_inherited_namespace,
_is_polymorphic_subclass,
finish_init,
get_annotations,
get_field_metadata,
Expand DownExpand Up@@ -578,9 +582,22 @@ def __new__(
config_kwargs = {
key: kwargs[key] for key in kwargs.keys() & allowed_config_kwargs
}
new_cls = cast(
"SQLModel", super().__new__(cls, name, bases, dict_used, **config_kwargs)
)
dict_used = _collect_inherited_namespace(bases, dict_used)
if _is_polymorphic_subclass(bases):
with warnings.catch_warnings():
warnings.filterwarnings(
"ignore",
message="Field name .+ shadows an attribute in parent.+",
)
new_cls = cast(
"SQLModel",
super().__new__(cls, name, bases, dict_used, **config_kwargs),
)
else:
new_cls = cast(
"SQLModel",
super().__new__(cls, name, bases, dict_used, **config_kwargs),
)
new_cls.__annotations__ = {
**relationship_annotations,
**pydantic_annotations,
Expand All@@ -598,9 +615,16 @@ def get_config(name: str) -> Any:

config_table = get_config("table")
if config_table is True:
if new_cls.__name__ != "SQLModel" and not hasattr(new_cls, "__tablename__"):
setattr(new_cls, "__tablename__", new_cls.__name__.lower()) # noqa: B010
# If it was passed by kwargs, ensure it's also set in config
new_cls.model_config["table"] = config_table
for k, v in get_model_fields(new_cls).items():
if (
isinstance(getattr(new_cls, k, None), InstrumentedAttribute)
and k not in class_dict
):
continue
col = get_column_from_field(v)
setattr(new_cls, k, col)
# Set a config flag to tell FastAPI that this should be read with a field
Expand DownExpand Up@@ -632,7 +656,12 @@ def __init__(
# trying to create a new SQLAlchemy, for a new table, with the same name, that
# triggers an error
base_is_table = any(is_table_model_class(base) for base in bases)
if is_table_model_class(cls) and not base_is_table:
_mapper_args = dict_.get("__mapper_args__", {})
has_polymorphic = (
_mapper_args.get("polymorphic_identity") is not None
or _mapper_args.get("polymorphic_abstract") is not None
)
if is_table_model_class(cls) and (not base_is_table or has_polymorphic):
for rel_name, rel_info in cls.__sqlmodel_relationships__.items():
if rel_info.sa_relationship:
# There's a SQLAlchemy relationship declared, that takes precedence
Expand DownExpand Up@@ -737,10 +766,10 @@ def get_sqlalchemy_type(field: Any) -> Any:
raise ValueError(f"{type_} has no matching SQLAlchemy type")


def get_column_from_field(field: Any) -> Column:
def get_column_from_field(field: Any) -> Column | MappedColumn: # type: ignore
field_info = field
sa_column = _get_sqlmodel_field_value(field_info, "sa_column", Undefined)
if isinstance(sa_column, Column):
if isinstance(sa_column, Column) or isinstance(sa_column, MappedColumn):
return sa_column
sa_type = get_sqlalchemy_type(field)
primary_key = _get_sqlmodel_field_value(field_info, "primary_key", Undefined)
Expand DownExpand Up@@ -804,7 +833,6 @@ def get_column_from_field(field: Any) -> Column:
class SQLModel(BaseModel, metaclass=SQLModelMetaclass, registry=default_registry):
# SQLAlchemy needs to set weakref(s), Pydantic will set the other slots values
__slots__ = ("__weakref__",)
__tablename__: ClassVar[str | Callable[..., str]]
__sqlmodel_relationships__: ClassVar[builtins.dict[str, RelationshipProperty[Any]]]
__name__: ClassVar[str]
metadata: ClassVar[MetaData]
Expand DownExpand Up@@ -843,6 +871,14 @@ def __init__(__pydantic_self__, **data: Any) -> None:
if finish_init.get():
sqlmodel_init(self=__pydantic_self__, data=data)

def _is_sqlmodel_relationship(self, name: str) -> bool:
if name in self.__sqlmodel_relationships__:
return True
if not (is_table_model_class(self.__class__) and is_instrumented(self, name)):
return False
mapper = inspect(self.__class__, raiseerr=False)
return mapper is not None and name in mapper.relationships

def __setattr__(self, name: str, value: Any) -> None:
if name in {"_sa_instance_state"}:
self.__dict__[name] = value
Expand All@@ -853,7 +889,7 @@ def __setattr__(self, name: str, value: Any) -> None:
set_attribute(self, name, value)
# Set in Pydantic model to trigger possible validation changes, only for
# non relationship values
if name not in self.__sqlmodel_relationships__:
if not self._is_sqlmodel_relationship(name):
super().__setattr__(name, value)

def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
Expand All@@ -864,10 +900,6 @@ def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
if not (isinstance(k, str) and k.startswith("_sa_"))
]

@declared_attr # type: ignore
def __tablename__(cls) -> str:
return cls.__name__.lower()

@classmethod
def model_validate( # ty: ignore[invalid-method-override]
cls: type[_TSQLModel],
Expand Down
Empty file addedtests/test_polymorphic/__init__.py
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Open in desktop
Empty file.
Loading
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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Add support for polymorphism models#1894

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privacy statement. We’ll occasionally send you account related emails.

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 Open

viet-hung-ng
wants to merge
4
commits into

base:main
Choose a base branch

from

 Open


Add support for polymorphism models
#1894
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61d6676

Add metaclass support for SQLAlchemy polymorphic models (joined-table…


ng-viet-hung Apr 28, 2026
c2851b2

Fix inherited relationship resolution in polymorphic subclass constru…


ng-viet-hung Apr 28, 2026
98c63d4

Add test suite for polymorphic inheritance


ng-viet-hung Apr 28, 2026
ff38e5c

Fix formatting


ng-viet-hung May 4, 2026

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105 changes: 102 additions & 3 deletions
sqlmodel/_compat.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,13 +1,14 @@
import sys
import types
from collections.abc import Generator
from collections.abc import Generator, Iterable
from contextlib import contextmanager
from contextvars import ContextVar
from dataclasses import dataclass
from typing import (
 TYPE_CHECKING,
 Annotated,
 Any,
 ClassVar,
 ForwardRef,
 TypeAlias,
 TypeVar,
Expand All@@ -26,6 +27,8 @@
from pydantic.fields import FieldInfo
from pydantic_core import PydanticUndefined as Undefined
from pydantic_core import PydanticUndefinedType as PydanticUndefinedType
from sqlalchemy import inspect
from sqlalchemy.orm import Mapper

BaseConfig = ConfigDict
UndefinedType = PydanticUndefinedType
Expand DownExpand Up@@ -68,6 +71,100 @@ def _is_union_type(t: Any) -> bool:
finish_init: ContextVar[bool] = ContextVar("finish_init", default=True)


def set_polymorphic_default_value(
 self_instance: _TSQLModel,
 values: dict[str, Any],
) -> bool:
 """By default, when init a model, pydantic will set the polymorphic_on
 value to field default value. But when inherit a model, the polymorphic_on
 should be set to polymorphic_identity value by default."""
 cls = type(self_instance)
 mapper = inspect(cls)
 ret = False
 if isinstance(mapper, Mapper):
 polymorphic_on = mapper.polymorphic_on
 if polymorphic_on is not None:
 polymorphic_property = mapper.get_property_by_column(polymorphic_on)
 field_info = get_model_fields(cls).get(polymorphic_property.key)
 if field_info:
 v = values.get(polymorphic_property.key)
 if mapper.inherits or v is None:
 setattr(
 self_instance,
 polymorphic_property.key,
 mapper.polymorphic_identity,
 )
 ret = True
 return ret


def _wrap_inherited_relationships_as_classvar(
 base: type,
 base_annotations: dict[str, Any],
 dict_used: dict[str, Any],
) -> None:
 """Convert inherited relationship annotations to ClassVar on the subclass.

 Pydantic would try to treat inherited SQLAlchemy relationship descriptors as plain
 fields, which fails at class-creation time. Tagging them ClassVar tells
 Pydantic to ignore them while SQLAlchemy continues to own the attribute.
 """
 if not hasattr(base, "__sqlmodel_relationships__"):
 return
 for k in base.__sqlmodel_relationships__:
 anno = base_annotations.get(k, Any)
 if get_origin(anno) is not ClassVar:
 dict_used["__annotations__"][k] = ClassVar[anno] # type: ignore[valid-type]


def _is_polymorphic_subclass(bases: tuple[type, ...]) -> bool:
 """Return True when any base class already defines a ``__tablename__``.

 This distinguishes a polymorphic subclass (which inherits from an existing
 table model) from a root table model that defines its own table.
 """
 return any(
 issubclass(base, BaseModel) and hasattr(base, "__tablename__") for base in bases
 )


def _collect_inherited_namespace(
 bases: tuple[type, ...],
 dict_used: dict[str, Any],
) -> dict[str, Any]:
 """Merge base-class fields/annotations into *dict_used* for polymorphic subclasses.

 Walks bases in method resolution order (reversed so the most-specific base wins),
 collecting Pydantic field definitions and annotations from every
 SQLModel table parent, and marking inherited relationships as ClassVar
 so Pydantic ignores them.
 """
 base_fields: dict[str, Any] = {}
 base_annotations: dict[str, Any] = {}
 for base in bases[::-1]:
 if not issubclass(base, BaseModel):
 continue
 base_model_fields = get_model_fields(base)
 base_fields.update(base_model_fields)
 for k in base_model_fields:
 if k in base.__annotations__:
 base_annotations[k] = base.__annotations__[k]
 _wrap_inherited_relationships_as_classvar(base, base_annotations, dict_used)
 base_annotations.update(dict_used["__annotations__"])
 dict_used["__annotations__"] = base_annotations
 base_fields.update(dict_used)
 return base_fields


def _relationship_keys(instance: _TSQLModel) -> Iterable[str]:
 mapper = inspect(type(instance), raiseerr=False)
 return (
 mapper.relationships.keys()
 if mapper is not None
 else instance.__sqlmodel_relationships__
 )


@contextmanager
def partial_init() -> Generator[None, None, None]:
 token = finish_init.set(False)
Expand DownExpand Up@@ -265,11 +362,13 @@ def sqlmodel_table_construct(
 object.__setattr__(self_instance, "__pydantic_private__", None)
 # SQLModel override, set relationships
 # Get and set any relationship objects
 for key in self_instance.__sqlmodel_relationships__:
 for key in _relationship_keys(self_instance):
 value = values.get(key, Undefined)
 if value is not Undefined:
 setattr(self_instance, key, value)
 # End SQLModel override
 # Override polymorphic_on default value
 set_polymorphic_default_value(self_instance, values)
 return self_instance


Expand DownExpand Up@@ -319,7 +418,7 @@ def sqlmodel_validate(
 object.__setattr__(new_obj, "__pydantic_fields_set__", fields_set)
 # Get and set any relationship objects
 if is_table_model_class(cls):
 for key in new_obj.__sqlmodel_relationships__:
 for key in _relationship_keys(new_obj):
 value = getattr(use_obj, key, Undefined)
 if value is not Undefined:
 setattr(new_obj, key, value)
Expand Down

58 changes: 45 additions & 13 deletions
sqlmodel/main.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3,6 +3,7 @@
import builtins
import ipaddress
import uuid
import warnings
from collections.abc import Callable, Mapping, Sequence, Set
from dataclasses import dataclass
from datetime import date, datetime, time, timedelta
Expand DownExpand Up@@ -38,9 +39,10 @@
)
from sqlalchemy import Enum as sa_Enum
from sqlalchemy.orm import (
 InstrumentedAttribute,
 Mapped,
 MappedColumn,
 RelationshipProperty,
 declared_attr,
 registry,
 relationship,
)
Expand All@@ -59,6 +61,8 @@
 SQLModelConfig,
 Undefined,
 UndefinedType,
 _collect_inherited_namespace,
 _is_polymorphic_subclass,
 finish_init,
 get_annotations,
 get_field_metadata,
Expand DownExpand Up@@ -578,9 +582,22 @@ def __new__(
 config_kwargs = {
 key: kwargs[key] for key in kwargs.keys() & allowed_config_kwargs
 }
 new_cls = cast(
 "SQLModel", super().__new__(cls, name, bases, dict_used, **config_kwargs)
 )
 dict_used = _collect_inherited_namespace(bases, dict_used)
 if _is_polymorphic_subclass(bases):
 with warnings.catch_warnings():
 warnings.filterwarnings(
 "ignore",
 message="Field name .+ shadows an attribute in parent.+",
 )
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 else:
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 new_cls.__annotations__ = {
 **relationship_annotations,
 **pydantic_annotations,
Expand All@@ -598,9 +615,16 @@ def get_config(name: str) -> Any:

 config_table = get_config("table")
 if config_table is True:
 if new_cls.__name__ != "SQLModel" and not hasattr(new_cls, "__tablename__"):
 setattr(new_cls, "__tablename__", new_cls.__name__.lower()) # noqa: B010
 # If it was passed by kwargs, ensure it's also set in config
 new_cls.model_config["table"] = config_table
 for k, v in get_model_fields(new_cls).items():
 if (
 isinstance(getattr(new_cls, k, None), InstrumentedAttribute)
 and k not in class_dict
 ):
 continue
 col = get_column_from_field(v)
 setattr(new_cls, k, col)
 # Set a config flag to tell FastAPI that this should be read with a field
Expand DownExpand Up@@ -632,7 +656,12 @@ def __init__(
 # trying to create a new SQLAlchemy, for a new table, with the same name, that
 # triggers an error
 base_is_table = any(is_table_model_class(base) for base in bases)
 if is_table_model_class(cls) and not base_is_table:
 _mapper_args = dict_.get("__mapper_args__", {})
 has_polymorphic = (
 _mapper_args.get("polymorphic_identity") is not None
 or _mapper_args.get("polymorphic_abstract") is not None
 )
 if is_table_model_class(cls) and (not base_is_table or has_polymorphic):
 for rel_name, rel_info in cls.__sqlmodel_relationships__.items():
 if rel_info.sa_relationship:
 # There's a SQLAlchemy relationship declared, that takes precedence
Expand DownExpand Up@@ -737,10 +766,10 @@ def get_sqlalchemy_type(field: Any) -> Any:
 raise ValueError(f"{type_} has no matching SQLAlchemy type")


def get_column_from_field(field: Any) -> Column:
def get_column_from_field(field: Any) -> Column | MappedColumn: # type: ignore
 field_info = field
 sa_column = _get_sqlmodel_field_value(field_info, "sa_column", Undefined)
 if isinstance(sa_column, Column):
 if isinstance(sa_column, Column) or isinstance(sa_column, MappedColumn):
 return sa_column
 sa_type = get_sqlalchemy_type(field)
 primary_key = _get_sqlmodel_field_value(field_info, "primary_key", Undefined)
Expand DownExpand Up@@ -804,7 +833,6 @@ def get_column_from_field(field: Any) -> Column:
class SQLModel(BaseModel, metaclass=SQLModelMetaclass, registry=default_registry):
 # SQLAlchemy needs to set weakref(s), Pydantic will set the other slots values
 __slots__ = ("__weakref__",)
 __tablename__: ClassVar[str | Callable[..., str]]
 __sqlmodel_relationships__: ClassVar[builtins.dict[str, RelationshipProperty[Any]]]
 __name__: ClassVar[str]
 metadata: ClassVar[MetaData]
Expand DownExpand Up@@ -843,6 +871,14 @@ def __init__(__pydantic_self__, **data: Any) -> None:
 if finish_init.get():
 sqlmodel_init(self=__pydantic_self__, data=data)

 def _is_sqlmodel_relationship(self, name: str) -> bool:
 if name in self.__sqlmodel_relationships__:
 return True
 if not (is_table_model_class(self.__class__) and is_instrumented(self, name)):
 return False
 mapper = inspect(self.__class__, raiseerr=False)
 return mapper is not None and name in mapper.relationships

 def __setattr__(self, name: str, value: Any) -> None:
 if name in {"_sa_instance_state"}:
 self.__dict__[name] = value
Expand All@@ -853,7 +889,7 @@ def __setattr__(self, name: str, value: Any) -> None:
 set_attribute(self, name, value)
 # Set in Pydantic model to trigger possible validation changes, only for
 # non relationship values
 if name not in self.__sqlmodel_relationships__:
 if not self._is_sqlmodel_relationship(name):
 super().__setattr__(name, value)

 def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
Expand All@@ -864,10 +900,6 @@ def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
 if not (isinstance(k, str) and k.startswith("_sa_"))
 ]

 @declared_attr # type: ignore
 def __tablename__(cls) -> str:
 return cls.__name__.lower()

 @classmethod
 def model_validate( # ty: ignore[invalid-method-override]
 cls: type[_TSQLModel],
Expand Down
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} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
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var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Add support for polymorphism models
#1894
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61d6676

Add metaclass support for SQLAlchemy polymorphic models (joined-table…


ng-viet-hung Apr 28, 2026
c2851b2

Fix inherited relationship resolution in polymorphic subclass constru…


ng-viet-hung Apr 28, 2026
98c63d4

Add test suite for polymorphic inheritance


ng-viet-hung Apr 28, 2026
ff38e5c

Fix formatting


ng-viet-hung May 4, 2026

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105 changes: 102 additions & 3 deletions
sqlmodel/_compat.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,13 +1,14 @@
import sys
import types
from collections.abc import Generator
from collections.abc import Generator, Iterable
from contextlib import contextmanager
from contextvars import ContextVar
from dataclasses import dataclass
from typing import (
 TYPE_CHECKING,
 Annotated,
 Any,
 ClassVar,
 ForwardRef,
 TypeAlias,
 TypeVar,
Expand All@@ -26,6 +27,8 @@
from pydantic.fields import FieldInfo
from pydantic_core import PydanticUndefined as Undefined
from pydantic_core import PydanticUndefinedType as PydanticUndefinedType
from sqlalchemy import inspect
from sqlalchemy.orm import Mapper

BaseConfig = ConfigDict
UndefinedType = PydanticUndefinedType
Expand DownExpand Up@@ -68,6 +71,100 @@ def _is_union_type(t: Any) -> bool:
finish_init: ContextVar[bool] = ContextVar("finish_init", default=True)


def set_polymorphic_default_value(
 self_instance: _TSQLModel,
 values: dict[str, Any],
) -> bool:
 """By default, when init a model, pydantic will set the polymorphic_on
 value to field default value. But when inherit a model, the polymorphic_on
 should be set to polymorphic_identity value by default."""
 cls = type(self_instance)
 mapper = inspect(cls)
 ret = False
 if isinstance(mapper, Mapper):
 polymorphic_on = mapper.polymorphic_on
 if polymorphic_on is not None:
 polymorphic_property = mapper.get_property_by_column(polymorphic_on)
 field_info = get_model_fields(cls).get(polymorphic_property.key)
 if field_info:
 v = values.get(polymorphic_property.key)
 if mapper.inherits or v is None:
 setattr(
 self_instance,
 polymorphic_property.key,
 mapper.polymorphic_identity,
 )
 ret = True
 return ret


def _wrap_inherited_relationships_as_classvar(
 base: type,
 base_annotations: dict[str, Any],
 dict_used: dict[str, Any],
) -> None:
 """Convert inherited relationship annotations to ClassVar on the subclass.

 Pydantic would try to treat inherited SQLAlchemy relationship descriptors as plain
 fields, which fails at class-creation time. Tagging them ClassVar tells
 Pydantic to ignore them while SQLAlchemy continues to own the attribute.
 """
 if not hasattr(base, "__sqlmodel_relationships__"):
 return
 for k in base.__sqlmodel_relationships__:
 anno = base_annotations.get(k, Any)
 if get_origin(anno) is not ClassVar:
 dict_used["__annotations__"][k] = ClassVar[anno] # type: ignore[valid-type]


def _is_polymorphic_subclass(bases: tuple[type, ...]) -> bool:
 """Return True when any base class already defines a ``__tablename__``.

 This distinguishes a polymorphic subclass (which inherits from an existing
 table model) from a root table model that defines its own table.
 """
 return any(
 issubclass(base, BaseModel) and hasattr(base, "__tablename__") for base in bases
 )


def _collect_inherited_namespace(
 bases: tuple[type, ...],
 dict_used: dict[str, Any],
) -> dict[str, Any]:
 """Merge base-class fields/annotations into *dict_used* for polymorphic subclasses.

 Walks bases in method resolution order (reversed so the most-specific base wins),
 collecting Pydantic field definitions and annotations from every
 SQLModel table parent, and marking inherited relationships as ClassVar
 so Pydantic ignores them.
 """
 base_fields: dict[str, Any] = {}
 base_annotations: dict[str, Any] = {}
 for base in bases[::-1]:
 if not issubclass(base, BaseModel):
 continue
 base_model_fields = get_model_fields(base)
 base_fields.update(base_model_fields)
 for k in base_model_fields:
 if k in base.__annotations__:
 base_annotations[k] = base.__annotations__[k]
 _wrap_inherited_relationships_as_classvar(base, base_annotations, dict_used)
 base_annotations.update(dict_used["__annotations__"])
 dict_used["__annotations__"] = base_annotations
 base_fields.update(dict_used)
 return base_fields


def _relationship_keys(instance: _TSQLModel) -> Iterable[str]:
 mapper = inspect(type(instance), raiseerr=False)
 return (
 mapper.relationships.keys()
 if mapper is not None
 else instance.__sqlmodel_relationships__
 )


@contextmanager
def partial_init() -> Generator[None, None, None]:
 token = finish_init.set(False)
Expand DownExpand Up@@ -265,11 +362,13 @@ def sqlmodel_table_construct(
 object.__setattr__(self_instance, "__pydantic_private__", None)
 # SQLModel override, set relationships
 # Get and set any relationship objects
 for key in self_instance.__sqlmodel_relationships__:
 for key in _relationship_keys(self_instance):
 value = values.get(key, Undefined)
 if value is not Undefined:
 setattr(self_instance, key, value)
 # End SQLModel override
 # Override polymorphic_on default value
 set_polymorphic_default_value(self_instance, values)
 return self_instance


Expand DownExpand Up@@ -319,7 +418,7 @@ def sqlmodel_validate(
 object.__setattr__(new_obj, "__pydantic_fields_set__", fields_set)
 # Get and set any relationship objects
 if is_table_model_class(cls):
 for key in new_obj.__sqlmodel_relationships__:
 for key in _relationship_keys(new_obj):
 value = getattr(use_obj, key, Undefined)
 if value is not Undefined:
 setattr(new_obj, key, value)
Expand Down

58 changes: 45 additions & 13 deletions
sqlmodel/main.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3,6 +3,7 @@
import builtins
import ipaddress
import uuid
import warnings
from collections.abc import Callable, Mapping, Sequence, Set
from dataclasses import dataclass
from datetime import date, datetime, time, timedelta
Expand DownExpand Up@@ -38,9 +39,10 @@
)
from sqlalchemy import Enum as sa_Enum
from sqlalchemy.orm import (
 InstrumentedAttribute,
 Mapped,
 MappedColumn,
 RelationshipProperty,
 declared_attr,
 registry,
 relationship,
)
Expand All@@ -59,6 +61,8 @@
 SQLModelConfig,
 Undefined,
 UndefinedType,
 _collect_inherited_namespace,
 _is_polymorphic_subclass,
 finish_init,
 get_annotations,
 get_field_metadata,
Expand DownExpand Up@@ -578,9 +582,22 @@ def __new__(
 config_kwargs = {
 key: kwargs[key] for key in kwargs.keys() & allowed_config_kwargs
 }
 new_cls = cast(
 "SQLModel", super().__new__(cls, name, bases, dict_used, **config_kwargs)
 )
 dict_used = _collect_inherited_namespace(bases, dict_used)
 if _is_polymorphic_subclass(bases):
 with warnings.catch_warnings():
 warnings.filterwarnings(
 "ignore",
 message="Field name .+ shadows an attribute in parent.+",
 )
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 else:
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 new_cls.__annotations__ = {
 **relationship_annotations,
 **pydantic_annotations,
Expand All@@ -598,9 +615,16 @@ def get_config(name: str) -> Any:

 config_table = get_config("table")
 if config_table is True:
 if new_cls.__name__ != "SQLModel" and not hasattr(new_cls, "__tablename__"):
 setattr(new_cls, "__tablename__", new_cls.__name__.lower()) # noqa: B010
 # If it was passed by kwargs, ensure it's also set in config
 new_cls.model_config["table"] = config_table
 for k, v in get_model_fields(new_cls).items():
 if (
 isinstance(getattr(new_cls, k, None), InstrumentedAttribute)
 and k not in class_dict
 ):
 continue
 col = get_column_from_field(v)
 setattr(new_cls, k, col)
 # Set a config flag to tell FastAPI that this should be read with a field
Expand DownExpand Up@@ -632,7 +656,12 @@ def __init__(
 # trying to create a new SQLAlchemy, for a new table, with the same name, that
 # triggers an error
 base_is_table = any(is_table_model_class(base) for base in bases)
 if is_table_model_class(cls) and not base_is_table:
 _mapper_args = dict_.get("__mapper_args__", {})
 has_polymorphic = (
 _mapper_args.get("polymorphic_identity") is not None
 or _mapper_args.get("polymorphic_abstract") is not None
 )
 if is_table_model_class(cls) and (not base_is_table or has_polymorphic):
 for rel_name, rel_info in cls.__sqlmodel_relationships__.items():
 if rel_info.sa_relationship:
 # There's a SQLAlchemy relationship declared, that takes precedence
Expand DownExpand Up@@ -737,10 +766,10 @@ def get_sqlalchemy_type(field: Any) -> Any:
 raise ValueError(f"{type_} has no matching SQLAlchemy type")


def get_column_from_field(field: Any) -> Column:
def get_column_from_field(field: Any) -> Column | MappedColumn: # type: ignore
 field_info = field
 sa_column = _get_sqlmodel_field_value(field_info, "sa_column", Undefined)
 if isinstance(sa_column, Column):
 if isinstance(sa_column, Column) or isinstance(sa_column, MappedColumn):
 return sa_column
 sa_type = get_sqlalchemy_type(field)
 primary_key = _get_sqlmodel_field_value(field_info, "primary_key", Undefined)
Expand DownExpand Up@@ -804,7 +833,6 @@ def get_column_from_field(field: Any) -> Column:
class SQLModel(BaseModel, metaclass=SQLModelMetaclass, registry=default_registry):
 # SQLAlchemy needs to set weakref(s), Pydantic will set the other slots values
 __slots__ = ("__weakref__",)
 __tablename__: ClassVar[str | Callable[..., str]]
 __sqlmodel_relationships__: ClassVar[builtins.dict[str, RelationshipProperty[Any]]]
 __name__: ClassVar[str]
 metadata: ClassVar[MetaData]
Expand DownExpand Up@@ -843,6 +871,14 @@ def __init__(__pydantic_self__, **data: Any) -> None:
 if finish_init.get():
 sqlmodel_init(self=__pydantic_self__, data=data)

 def _is_sqlmodel_relationship(self, name: str) -> bool:
 if name in self.__sqlmodel_relationships__:
 return True
 if not (is_table_model_class(self.__class__) and is_instrumented(self, name)):
 return False
 mapper = inspect(self.__class__, raiseerr=False)
 return mapper is not None and name in mapper.relationships

 def __setattr__(self, name: str, value: Any) -> None:
 if name in {"_sa_instance_state"}:
 self.__dict__[name] = value
Expand All@@ -853,7 +889,7 @@ def __setattr__(self, name: str, value: Any) -> None:
 set_attribute(self, name, value)
 # Set in Pydantic model to trigger possible validation changes, only for
 # non relationship values
 if name not in self.__sqlmodel_relationships__:
 if not self._is_sqlmodel_relationship(name):
 super().__setattr__(name, value)

 def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
Expand All@@ -864,10 +900,6 @@ def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
 if not (isinstance(k, str) and k.startswith("_sa_"))
 ]

 @declared_attr # type: ignore
 def __tablename__(cls) -> str:
 return cls.__name__.lower()

 @classmethod
 def model_validate( # ty: ignore[invalid-method-override]
 cls: type[_TSQLModel],
Expand Down
Empty file addedtests/test_polymorphic/__init__.py

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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Add support for polymorphism models#1894

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viet-hung-ng
wants to merge
4
commits into

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Add support for polymorphism models
#1894
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61d6676

Add metaclass support for SQLAlchemy polymorphic models (joined-table…


ng-viet-hung Apr 28, 2026
c2851b2

Fix inherited relationship resolution in polymorphic subclass constru…


ng-viet-hung Apr 28, 2026
98c63d4

Add test suite for polymorphic inheritance


ng-viet-hung Apr 28, 2026
ff38e5c

Fix formatting


ng-viet-hung May 4, 2026

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105 changes: 102 additions & 3 deletions
sqlmodel/_compat.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,13 +1,14 @@
import sys
import types
from collections.abc import Generator
from collections.abc import Generator, Iterable
from contextlib import contextmanager
from contextvars import ContextVar
from dataclasses import dataclass
from typing import (
 TYPE_CHECKING,
 Annotated,
 Any,
 ClassVar,
 ForwardRef,
 TypeAlias,
 TypeVar,
Expand All@@ -26,6 +27,8 @@
from pydantic.fields import FieldInfo
from pydantic_core import PydanticUndefined as Undefined
from pydantic_core import PydanticUndefinedType as PydanticUndefinedType
from sqlalchemy import inspect
from sqlalchemy.orm import Mapper

BaseConfig = ConfigDict
UndefinedType = PydanticUndefinedType
Expand DownExpand Up@@ -68,6 +71,100 @@ def _is_union_type(t: Any) -> bool:
finish_init: ContextVar[bool] = ContextVar("finish_init", default=True)


def set_polymorphic_default_value(
 self_instance: _TSQLModel,
 values: dict[str, Any],
) -> bool:
 """By default, when init a model, pydantic will set the polymorphic_on
 value to field default value. But when inherit a model, the polymorphic_on
 should be set to polymorphic_identity value by default."""
 cls = type(self_instance)
 mapper = inspect(cls)
 ret = False
 if isinstance(mapper, Mapper):
 polymorphic_on = mapper.polymorphic_on
 if polymorphic_on is not None:
 polymorphic_property = mapper.get_property_by_column(polymorphic_on)
 field_info = get_model_fields(cls).get(polymorphic_property.key)
 if field_info:
 v = values.get(polymorphic_property.key)
 if mapper.inherits or v is None:
 setattr(
 self_instance,
 polymorphic_property.key,
 mapper.polymorphic_identity,
 )
 ret = True
 return ret


def _wrap_inherited_relationships_as_classvar(
 base: type,
 base_annotations: dict[str, Any],
 dict_used: dict[str, Any],
) -> None:
 """Convert inherited relationship annotations to ClassVar on the subclass.

 Pydantic would try to treat inherited SQLAlchemy relationship descriptors as plain
 fields, which fails at class-creation time. Tagging them ClassVar tells
 Pydantic to ignore them while SQLAlchemy continues to own the attribute.
 """
 if not hasattr(base, "__sqlmodel_relationships__"):
 return
 for k in base.__sqlmodel_relationships__:
 anno = base_annotations.get(k, Any)
 if get_origin(anno) is not ClassVar:
 dict_used["__annotations__"][k] = ClassVar[anno] # type: ignore[valid-type]


def _is_polymorphic_subclass(bases: tuple[type, ...]) -> bool:
 """Return True when any base class already defines a ``__tablename__``.

 This distinguishes a polymorphic subclass (which inherits from an existing
 table model) from a root table model that defines its own table.
 """
 return any(
 issubclass(base, BaseModel) and hasattr(base, "__tablename__") for base in bases
 )


def _collect_inherited_namespace(
 bases: tuple[type, ...],
 dict_used: dict[str, Any],
) -> dict[str, Any]:
 """Merge base-class fields/annotations into *dict_used* for polymorphic subclasses.

 Walks bases in method resolution order (reversed so the most-specific base wins),
 collecting Pydantic field definitions and annotations from every
 SQLModel table parent, and marking inherited relationships as ClassVar
 so Pydantic ignores them.
 """
 base_fields: dict[str, Any] = {}
 base_annotations: dict[str, Any] = {}
 for base in bases[::-1]:
 if not issubclass(base, BaseModel):
 continue
 base_model_fields = get_model_fields(base)
 base_fields.update(base_model_fields)
 for k in base_model_fields:
 if k in base.__annotations__:
 base_annotations[k] = base.__annotations__[k]
 _wrap_inherited_relationships_as_classvar(base, base_annotations, dict_used)
 base_annotations.update(dict_used["__annotations__"])
 dict_used["__annotations__"] = base_annotations
 base_fields.update(dict_used)
 return base_fields


def _relationship_keys(instance: _TSQLModel) -> Iterable[str]:
 mapper = inspect(type(instance), raiseerr=False)
 return (
 mapper.relationships.keys()
 if mapper is not None
 else instance.__sqlmodel_relationships__
 )


@contextmanager
def partial_init() -> Generator[None, None, None]:
 token = finish_init.set(False)
Expand DownExpand Up@@ -265,11 +362,13 @@ def sqlmodel_table_construct(
 object.__setattr__(self_instance, "__pydantic_private__", None)
 # SQLModel override, set relationships
 # Get and set any relationship objects
 for key in self_instance.__sqlmodel_relationships__:
 for key in _relationship_keys(self_instance):
 value = values.get(key, Undefined)
 if value is not Undefined:
 setattr(self_instance, key, value)
 # End SQLModel override
 # Override polymorphic_on default value
 set_polymorphic_default_value(self_instance, values)
 return self_instance


Expand DownExpand Up@@ -319,7 +418,7 @@ def sqlmodel_validate(
 object.__setattr__(new_obj, "__pydantic_fields_set__", fields_set)
 # Get and set any relationship objects
 if is_table_model_class(cls):
 for key in new_obj.__sqlmodel_relationships__:
 for key in _relationship_keys(new_obj):
 value = getattr(use_obj, key, Undefined)
 if value is not Undefined:
 setattr(new_obj, key, value)
Expand Down

58 changes: 45 additions & 13 deletions
sqlmodel/main.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3,6 +3,7 @@
import builtins
import ipaddress
import uuid
import warnings
from collections.abc import Callable, Mapping, Sequence, Set
from dataclasses import dataclass
from datetime import date, datetime, time, timedelta
Expand DownExpand Up@@ -38,9 +39,10 @@
)
from sqlalchemy import Enum as sa_Enum
from sqlalchemy.orm import (
 InstrumentedAttribute,
 Mapped,
 MappedColumn,
 RelationshipProperty,
 declared_attr,
 registry,
 relationship,
)
Expand All@@ -59,6 +61,8 @@
 SQLModelConfig,
 Undefined,
 UndefinedType,
 _collect_inherited_namespace,
 _is_polymorphic_subclass,
 finish_init,
 get_annotations,
 get_field_metadata,
Expand DownExpand Up@@ -578,9 +582,22 @@ def __new__(
 config_kwargs = {
 key: kwargs[key] for key in kwargs.keys() & allowed_config_kwargs
 }
 new_cls = cast(
 "SQLModel", super().__new__(cls, name, bases, dict_used, **config_kwargs)
 )
 dict_used = _collect_inherited_namespace(bases, dict_used)
 if _is_polymorphic_subclass(bases):
 with warnings.catch_warnings():
 warnings.filterwarnings(
 "ignore",
 message="Field name .+ shadows an attribute in parent.+",
 )
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 else:
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 new_cls.__annotations__ = {
 **relationship_annotations,
 **pydantic_annotations,
Expand All@@ -598,9 +615,16 @@ def get_config(name: str) -> Any:

 config_table = get_config("table")
 if config_table is True:
 if new_cls.__name__ != "SQLModel" and not hasattr(new_cls, "__tablename__"):
 setattr(new_cls, "__tablename__", new_cls.__name__.lower()) # noqa: B010
 # If it was passed by kwargs, ensure it's also set in config
 new_cls.model_config["table"] = config_table
 for k, v in get_model_fields(new_cls).items():
 if (
 isinstance(getattr(new_cls, k, None), InstrumentedAttribute)
 and k not in class_dict
 ):
 continue
 col = get_column_from_field(v)
 setattr(new_cls, k, col)
 # Set a config flag to tell FastAPI that this should be read with a field
Expand DownExpand Up@@ -632,7 +656,12 @@ def __init__(
 # trying to create a new SQLAlchemy, for a new table, with the same name, that
 # triggers an error
 base_is_table = any(is_table_model_class(base) for base in bases)
 if is_table_model_class(cls) and not base_is_table:
 _mapper_args = dict_.get("__mapper_args__", {})
 has_polymorphic = (
 _mapper_args.get("polymorphic_identity") is not None
 or _mapper_args.get("polymorphic_abstract") is not None
 )
 if is_table_model_class(cls) and (not base_is_table or has_polymorphic):
 for rel_name, rel_info in cls.__sqlmodel_relationships__.items():
 if rel_info.sa_relationship:
 # There's a SQLAlchemy relationship declared, that takes precedence
Expand DownExpand Up@@ -737,10 +766,10 @@ def get_sqlalchemy_type(field: Any) -> Any:
 raise ValueError(f"{type_} has no matching SQLAlchemy type")


def get_column_from_field(field: Any) -> Column:
def get_column_from_field(field: Any) -> Column | MappedColumn: # type: ignore
 field_info = field
 sa_column = _get_sqlmodel_field_value(field_info, "sa_column", Undefined)
 if isinstance(sa_column, Column):
 if isinstance(sa_column, Column) or isinstance(sa_column, MappedColumn):
 return sa_column
 sa_type = get_sqlalchemy_type(field)
 primary_key = _get_sqlmodel_field_value(field_info, "primary_key", Undefined)
Expand DownExpand Up@@ -804,7 +833,6 @@ def get_column_from_field(field: Any) -> Column:
class SQLModel(BaseModel, metaclass=SQLModelMetaclass, registry=default_registry):
 # SQLAlchemy needs to set weakref(s), Pydantic will set the other slots values
 __slots__ = ("__weakref__",)
 __tablename__: ClassVar[str | Callable[..., str]]
 __sqlmodel_relationships__: ClassVar[builtins.dict[str, RelationshipProperty[Any]]]
 __name__: ClassVar[str]
 metadata: ClassVar[MetaData]
Expand DownExpand Up@@ -843,6 +871,14 @@ def __init__(__pydantic_self__, **data: Any) -> None:
 if finish_init.get():
 sqlmodel_init(self=__pydantic_self__, data=data)

 def _is_sqlmodel_relationship(self, name: str) -> bool:
 if name in self.__sqlmodel_relationships__:
 return True
 if not (is_table_model_class(self.__class__) and is_instrumented(self, name)):
 return False
 mapper = inspect(self.__class__, raiseerr=False)
 return mapper is not None and name in mapper.relationships

 def __setattr__(self, name: str, value: Any) -> None:
 if name in {"_sa_instance_state"}:
 self.__dict__[name] = value
Expand All@@ -853,7 +889,7 @@ def __setattr__(self, name: str, value: Any) -> None:
 set_attribute(self, name, value)
 # Set in Pydantic model to trigger possible validation changes, only for
 # non relationship values
 if name not in self.__sqlmodel_relationships__:
 if not self._is_sqlmodel_relationship(name):
 super().__setattr__(name, value)

 def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
Expand All@@ -864,10 +900,6 @@ def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
 if not (isinstance(k, str) and k.startswith("_sa_"))
 ]

 @declared_attr # type: ignore
 def __tablename__(cls) -> str:
 return cls.__name__.lower()

 @classmethod
 def model_validate( # ty: ignore[invalid-method-override]
 cls: type[_TSQLModel],
Expand Down
Empty file addedtests/test_polymorphic/__init__.py

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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

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Add support for polymorphism models
#1894
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61d6676

Add metaclass support for SQLAlchemy polymorphic models (joined-table…


ng-viet-hung Apr 28, 2026
c2851b2

Fix inherited relationship resolution in polymorphic subclass constru…


ng-viet-hung Apr 28, 2026
98c63d4

Add test suite for polymorphic inheritance


ng-viet-hung Apr 28, 2026
ff38e5c

Fix formatting


ng-viet-hung May 4, 2026

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105 changes: 102 additions & 3 deletions
sqlmodel/_compat.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,13 +1,14 @@
import sys
import types
from collections.abc import Generator
from collections.abc import Generator, Iterable
from contextlib import contextmanager
from contextvars import ContextVar
from dataclasses import dataclass
from typing import (
 TYPE_CHECKING,
 Annotated,
 Any,
 ClassVar,
 ForwardRef,
 TypeAlias,
 TypeVar,
Expand All@@ -26,6 +27,8 @@
from pydantic.fields import FieldInfo
from pydantic_core import PydanticUndefined as Undefined
from pydantic_core import PydanticUndefinedType as PydanticUndefinedType
from sqlalchemy import inspect
from sqlalchemy.orm import Mapper

BaseConfig = ConfigDict
UndefinedType = PydanticUndefinedType
Expand DownExpand Up@@ -68,6 +71,100 @@ def _is_union_type(t: Any) -> bool:
finish_init: ContextVar[bool] = ContextVar("finish_init", default=True)


def set_polymorphic_default_value(
 self_instance: _TSQLModel,
 values: dict[str, Any],
) -> bool:
 """By default, when init a model, pydantic will set the polymorphic_on
 value to field default value. But when inherit a model, the polymorphic_on
 should be set to polymorphic_identity value by default."""
 cls = type(self_instance)
 mapper = inspect(cls)
 ret = False
 if isinstance(mapper, Mapper):
 polymorphic_on = mapper.polymorphic_on
 if polymorphic_on is not None:
 polymorphic_property = mapper.get_property_by_column(polymorphic_on)
 field_info = get_model_fields(cls).get(polymorphic_property.key)
 if field_info:
 v = values.get(polymorphic_property.key)
 if mapper.inherits or v is None:
 setattr(
 self_instance,
 polymorphic_property.key,
 mapper.polymorphic_identity,
 )
 ret = True
 return ret


def _wrap_inherited_relationships_as_classvar(
 base: type,
 base_annotations: dict[str, Any],
 dict_used: dict[str, Any],
) -> None:
 """Convert inherited relationship annotations to ClassVar on the subclass.

 Pydantic would try to treat inherited SQLAlchemy relationship descriptors as plain
 fields, which fails at class-creation time. Tagging them ClassVar tells
 Pydantic to ignore them while SQLAlchemy continues to own the attribute.
 """
 if not hasattr(base, "__sqlmodel_relationships__"):
 return
 for k in base.__sqlmodel_relationships__:
 anno = base_annotations.get(k, Any)
 if get_origin(anno) is not ClassVar:
 dict_used["__annotations__"][k] = ClassVar[anno] # type: ignore[valid-type]


def _is_polymorphic_subclass(bases: tuple[type, ...]) -> bool:
 """Return True when any base class already defines a ``__tablename__``.

 This distinguishes a polymorphic subclass (which inherits from an existing
 table model) from a root table model that defines its own table.
 """
 return any(
 issubclass(base, BaseModel) and hasattr(base, "__tablename__") for base in bases
 )


def _collect_inherited_namespace(
 bases: tuple[type, ...],
 dict_used: dict[str, Any],
) -> dict[str, Any]:
 """Merge base-class fields/annotations into *dict_used* for polymorphic subclasses.

 Walks bases in method resolution order (reversed so the most-specific base wins),
 collecting Pydantic field definitions and annotations from every
 SQLModel table parent, and marking inherited relationships as ClassVar
 so Pydantic ignores them.
 """
 base_fields: dict[str, Any] = {}
 base_annotations: dict[str, Any] = {}
 for base in bases[::-1]:
 if not issubclass(base, BaseModel):
 continue
 base_model_fields = get_model_fields(base)
 base_fields.update(base_model_fields)
 for k in base_model_fields:
 if k in base.__annotations__:
 base_annotations[k] = base.__annotations__[k]
 _wrap_inherited_relationships_as_classvar(base, base_annotations, dict_used)
 base_annotations.update(dict_used["__annotations__"])
 dict_used["__annotations__"] = base_annotations
 base_fields.update(dict_used)
 return base_fields


def _relationship_keys(instance: _TSQLModel) -> Iterable[str]:
 mapper = inspect(type(instance), raiseerr=False)
 return (
 mapper.relationships.keys()
 if mapper is not None
 else instance.__sqlmodel_relationships__
 )


@contextmanager
def partial_init() -> Generator[None, None, None]:
 token = finish_init.set(False)
Expand DownExpand Up@@ -265,11 +362,13 @@ def sqlmodel_table_construct(
 object.__setattr__(self_instance, "__pydantic_private__", None)
 # SQLModel override, set relationships
 # Get and set any relationship objects
 for key in self_instance.__sqlmodel_relationships__:
 for key in _relationship_keys(self_instance):
 value = values.get(key, Undefined)
 if value is not Undefined:
 setattr(self_instance, key, value)
 # End SQLModel override
 # Override polymorphic_on default value
 set_polymorphic_default_value(self_instance, values)
 return self_instance


Expand DownExpand Up@@ -319,7 +418,7 @@ def sqlmodel_validate(
 object.__setattr__(new_obj, "__pydantic_fields_set__", fields_set)
 # Get and set any relationship objects
 if is_table_model_class(cls):
 for key in new_obj.__sqlmodel_relationships__:
 for key in _relationship_keys(new_obj):
 value = getattr(use_obj, key, Undefined)
 if value is not Undefined:
 setattr(new_obj, key, value)
Expand Down

58 changes: 45 additions & 13 deletions
sqlmodel/main.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3,6 +3,7 @@
import builtins
import ipaddress
import uuid
import warnings
from collections.abc import Callable, Mapping, Sequence, Set
from dataclasses import dataclass
from datetime import date, datetime, time, timedelta
Expand DownExpand Up@@ -38,9 +39,10 @@
)
from sqlalchemy import Enum as sa_Enum
from sqlalchemy.orm import (
 InstrumentedAttribute,
 Mapped,
 MappedColumn,
 RelationshipProperty,
 declared_attr,
 registry,
 relationship,
)
Expand All@@ -59,6 +61,8 @@
 SQLModelConfig,
 Undefined,
 UndefinedType,
 _collect_inherited_namespace,
 _is_polymorphic_subclass,
 finish_init,
 get_annotations,
 get_field_metadata,
Expand DownExpand Up@@ -578,9 +582,22 @@ def __new__(
 config_kwargs = {
 key: kwargs[key] for key in kwargs.keys() & allowed_config_kwargs
 }
 new_cls = cast(
 "SQLModel", super().__new__(cls, name, bases, dict_used, **config_kwargs)
 )
 dict_used = _collect_inherited_namespace(bases, dict_used)
 if _is_polymorphic_subclass(bases):
 with warnings.catch_warnings():
 warnings.filterwarnings(
 "ignore",
 message="Field name .+ shadows an attribute in parent.+",
 )
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 else:
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 new_cls.__annotations__ = {
 **relationship_annotations,
 **pydantic_annotations,
Expand All@@ -598,9 +615,16 @@ def get_config(name: str) -> Any:

 config_table = get_config("table")
 if config_table is True:
 if new_cls.__name__ != "SQLModel" and not hasattr(new_cls, "__tablename__"):
 setattr(new_cls, "__tablename__", new_cls.__name__.lower()) # noqa: B010
 # If it was passed by kwargs, ensure it's also set in config
 new_cls.model_config["table"] = config_table
 for k, v in get_model_fields(new_cls).items():
 if (
 isinstance(getattr(new_cls, k, None), InstrumentedAttribute)
 and k not in class_dict
 ):
 continue
 col = get_column_from_field(v)
 setattr(new_cls, k, col)
 # Set a config flag to tell FastAPI that this should be read with a field
Expand DownExpand Up@@ -632,7 +656,12 @@ def __init__(
 # trying to create a new SQLAlchemy, for a new table, with the same name, that
 # triggers an error
 base_is_table = any(is_table_model_class(base) for base in bases)
 if is_table_model_class(cls) and not base_is_table:
 _mapper_args = dict_.get("__mapper_args__", {})
 has_polymorphic = (
 _mapper_args.get("polymorphic_identity") is not None
 or _mapper_args.get("polymorphic_abstract") is not None
 )
 if is_table_model_class(cls) and (not base_is_table or has_polymorphic):
 for rel_name, rel_info in cls.__sqlmodel_relationships__.items():
 if rel_info.sa_relationship:
 # There's a SQLAlchemy relationship declared, that takes precedence
Expand DownExpand Up@@ -737,10 +766,10 @@ def get_sqlalchemy_type(field: Any) -> Any:
 raise ValueError(f"{type_} has no matching SQLAlchemy type")


def get_column_from_field(field: Any) -> Column:
def get_column_from_field(field: Any) -> Column | MappedColumn: # type: ignore
 field_info = field
 sa_column = _get_sqlmodel_field_value(field_info, "sa_column", Undefined)
 if isinstance(sa_column, Column):
 if isinstance(sa_column, Column) or isinstance(sa_column, MappedColumn):
 return sa_column
 sa_type = get_sqlalchemy_type(field)
 primary_key = _get_sqlmodel_field_value(field_info, "primary_key", Undefined)
Expand DownExpand Up@@ -804,7 +833,6 @@ def get_column_from_field(field: Any) -> Column:
class SQLModel(BaseModel, metaclass=SQLModelMetaclass, registry=default_registry):
 # SQLAlchemy needs to set weakref(s), Pydantic will set the other slots values
 __slots__ = ("__weakref__",)
 __tablename__: ClassVar[str | Callable[..., str]]
 __sqlmodel_relationships__: ClassVar[builtins.dict[str, RelationshipProperty[Any]]]
 __name__: ClassVar[str]
 metadata: ClassVar[MetaData]
Expand DownExpand Up@@ -843,6 +871,14 @@ def __init__(__pydantic_self__, **data: Any) -> None:
 if finish_init.get():
 sqlmodel_init(self=__pydantic_self__, data=data)

 def _is_sqlmodel_relationship(self, name: str) -> bool:
 if name in self.__sqlmodel_relationships__:
 return True
 if not (is_table_model_class(self.__class__) and is_instrumented(self, name)):
 return False
 mapper = inspect(self.__class__, raiseerr=False)
 return mapper is not None and name in mapper.relationships

 def __setattr__(self, name: str, value: Any) -> None:
 if name in {"_sa_instance_state"}:
 self.__dict__[name] = value
Expand All@@ -853,7 +889,7 @@ def __setattr__(self, name: str, value: Any) -> None:
 set_attribute(self, name, value)
 # Set in Pydantic model to trigger possible validation changes, only for
 # non relationship values
 if name not in self.__sqlmodel_relationships__:
 if not self._is_sqlmodel_relationship(name):
 super().__setattr__(name, value)

 def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
Expand All@@ -864,10 +900,6 @@ def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
 if not (isinstance(k, str) and k.startswith("_sa_"))
 ]

 @declared_attr # type: ignore
 def __tablename__(cls) -> str:
 return cls.__name__.lower()

 @classmethod
 def model_validate( # ty: ignore[invalid-method-override]
 cls: type[_TSQLModel],
Expand Down
Empty file addedtests/test_polymorphic/__init__.py

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Open in desktop


Empty file.

Loading
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Add support for polymorphism models#1894

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Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

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privacy statement. We’ll occasionally send you account related emails.

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 Open

viet-hung-ng
wants to merge
4
commits into

base:main
Choose a base branch

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Add support for polymorphism models
#1894
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61d6676

Add metaclass support for SQLAlchemy polymorphic models (joined-table…


ng-viet-hung Apr 28, 2026
c2851b2

Fix inherited relationship resolution in polymorphic subclass constru…


ng-viet-hung Apr 28, 2026
98c63d4

Add test suite for polymorphic inheritance


ng-viet-hung Apr 28, 2026
ff38e5c

Fix formatting


ng-viet-hung May 4, 2026

File filter

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Filter by extension
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105 changes: 102 additions & 3 deletions
sqlmodel/_compat.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,13 +1,14 @@
import sys
import types
from collections.abc import Generator
from collections.abc import Generator, Iterable
from contextlib import contextmanager
from contextvars import ContextVar
from dataclasses import dataclass
from typing import (
 TYPE_CHECKING,
 Annotated,
 Any,
 ClassVar,
 ForwardRef,
 TypeAlias,
 TypeVar,
Expand All@@ -26,6 +27,8 @@
from pydantic.fields import FieldInfo
from pydantic_core import PydanticUndefined as Undefined
from pydantic_core import PydanticUndefinedType as PydanticUndefinedType
from sqlalchemy import inspect
from sqlalchemy.orm import Mapper

BaseConfig = ConfigDict
UndefinedType = PydanticUndefinedType
Expand DownExpand Up@@ -68,6 +71,100 @@ def _is_union_type(t: Any) -> bool:
finish_init: ContextVar[bool] = ContextVar("finish_init", default=True)


def set_polymorphic_default_value(
 self_instance: _TSQLModel,
 values: dict[str, Any],
) -> bool:
 """By default, when init a model, pydantic will set the polymorphic_on
 value to field default value. But when inherit a model, the polymorphic_on
 should be set to polymorphic_identity value by default."""
 cls = type(self_instance)
 mapper = inspect(cls)
 ret = False
 if isinstance(mapper, Mapper):
 polymorphic_on = mapper.polymorphic_on
 if polymorphic_on is not None:
 polymorphic_property = mapper.get_property_by_column(polymorphic_on)
 field_info = get_model_fields(cls).get(polymorphic_property.key)
 if field_info:
 v = values.get(polymorphic_property.key)
 if mapper.inherits or v is None:
 setattr(
 self_instance,
 polymorphic_property.key,
 mapper.polymorphic_identity,
 )
 ret = True
 return ret


def _wrap_inherited_relationships_as_classvar(
 base: type,
 base_annotations: dict[str, Any],
 dict_used: dict[str, Any],
) -> None:
 """Convert inherited relationship annotations to ClassVar on the subclass.

 Pydantic would try to treat inherited SQLAlchemy relationship descriptors as plain
 fields, which fails at class-creation time. Tagging them ClassVar tells
 Pydantic to ignore them while SQLAlchemy continues to own the attribute.
 """
 if not hasattr(base, "__sqlmodel_relationships__"):
 return
 for k in base.__sqlmodel_relationships__:
 anno = base_annotations.get(k, Any)
 if get_origin(anno) is not ClassVar:
 dict_used["__annotations__"][k] = ClassVar[anno] # type: ignore[valid-type]


def _is_polymorphic_subclass(bases: tuple[type, ...]) -> bool:
 """Return True when any base class already defines a ``__tablename__``.

 This distinguishes a polymorphic subclass (which inherits from an existing
 table model) from a root table model that defines its own table.
 """
 return any(
 issubclass(base, BaseModel) and hasattr(base, "__tablename__") for base in bases
 )


def _collect_inherited_namespace(
 bases: tuple[type, ...],
 dict_used: dict[str, Any],
) -> dict[str, Any]:
 """Merge base-class fields/annotations into *dict_used* for polymorphic subclasses.

 Walks bases in method resolution order (reversed so the most-specific base wins),
 collecting Pydantic field definitions and annotations from every
 SQLModel table parent, and marking inherited relationships as ClassVar
 so Pydantic ignores them.
 """
 base_fields: dict[str, Any] = {}
 base_annotations: dict[str, Any] = {}
 for base in bases[::-1]:
 if not issubclass(base, BaseModel):
 continue
 base_model_fields = get_model_fields(base)
 base_fields.update(base_model_fields)
 for k in base_model_fields:
 if k in base.__annotations__:
 base_annotations[k] = base.__annotations__[k]
 _wrap_inherited_relationships_as_classvar(base, base_annotations, dict_used)
 base_annotations.update(dict_used["__annotations__"])
 dict_used["__annotations__"] = base_annotations
 base_fields.update(dict_used)
 return base_fields


def _relationship_keys(instance: _TSQLModel) -> Iterable[str]:
 mapper = inspect(type(instance), raiseerr=False)
 return (
 mapper.relationships.keys()
 if mapper is not None
 else instance.__sqlmodel_relationships__
 )


@contextmanager
def partial_init() -> Generator[None, None, None]:
 token = finish_init.set(False)
Expand DownExpand Up@@ -265,11 +362,13 @@ def sqlmodel_table_construct(
 object.__setattr__(self_instance, "__pydantic_private__", None)
 # SQLModel override, set relationships
 # Get and set any relationship objects
 for key in self_instance.__sqlmodel_relationships__:
 for key in _relationship_keys(self_instance):
 value = values.get(key, Undefined)
 if value is not Undefined:
 setattr(self_instance, key, value)
 # End SQLModel override
 # Override polymorphic_on default value
 set_polymorphic_default_value(self_instance, values)
 return self_instance


Expand DownExpand Up@@ -319,7 +418,7 @@ def sqlmodel_validate(
 object.__setattr__(new_obj, "__pydantic_fields_set__", fields_set)
 # Get and set any relationship objects
 if is_table_model_class(cls):
 for key in new_obj.__sqlmodel_relationships__:
 for key in _relationship_keys(new_obj):
 value = getattr(use_obj, key, Undefined)
 if value is not Undefined:
 setattr(new_obj, key, value)
Expand Down

58 changes: 45 additions & 13 deletions
sqlmodel/main.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3,6 +3,7 @@
import builtins
import ipaddress
import uuid
import warnings
from collections.abc import Callable, Mapping, Sequence, Set
from dataclasses import dataclass
from datetime import date, datetime, time, timedelta
Expand DownExpand Up@@ -38,9 +39,10 @@
)
from sqlalchemy import Enum as sa_Enum
from sqlalchemy.orm import (
 InstrumentedAttribute,
 Mapped,
 MappedColumn,
 RelationshipProperty,
 declared_attr,
 registry,
 relationship,
)
Expand All@@ -59,6 +61,8 @@
 SQLModelConfig,
 Undefined,
 UndefinedType,
 _collect_inherited_namespace,
 _is_polymorphic_subclass,
 finish_init,
 get_annotations,
 get_field_metadata,
Expand DownExpand Up@@ -578,9 +582,22 @@ def __new__(
 config_kwargs = {
 key: kwargs[key] for key in kwargs.keys() & allowed_config_kwargs
 }
 new_cls = cast(
 "SQLModel", super().__new__(cls, name, bases, dict_used, **config_kwargs)
 )
 dict_used = _collect_inherited_namespace(bases, dict_used)
 if _is_polymorphic_subclass(bases):
 with warnings.catch_warnings():
 warnings.filterwarnings(
 "ignore",
 message="Field name .+ shadows an attribute in parent.+",
 )
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 else:
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 new_cls.__annotations__ = {
 **relationship_annotations,
 **pydantic_annotations,
Expand All@@ -598,9 +615,16 @@ def get_config(name: str) -> Any:

 config_table = get_config("table")
 if config_table is True:
 if new_cls.__name__ != "SQLModel" and not hasattr(new_cls, "__tablename__"):
 setattr(new_cls, "__tablename__", new_cls.__name__.lower()) # noqa: B010
 # If it was passed by kwargs, ensure it's also set in config
 new_cls.model_config["table"] = config_table
 for k, v in get_model_fields(new_cls).items():
 if (
 isinstance(getattr(new_cls, k, None), InstrumentedAttribute)
 and k not in class_dict
 ):
 continue
 col = get_column_from_field(v)
 setattr(new_cls, k, col)
 # Set a config flag to tell FastAPI that this should be read with a field
Expand DownExpand Up@@ -632,7 +656,12 @@ def __init__(
 # trying to create a new SQLAlchemy, for a new table, with the same name, that
 # triggers an error
 base_is_table = any(is_table_model_class(base) for base in bases)
 if is_table_model_class(cls) and not base_is_table:
 _mapper_args = dict_.get("__mapper_args__", {})
 has_polymorphic = (
 _mapper_args.get("polymorphic_identity") is not None
 or _mapper_args.get("polymorphic_abstract") is not None
 )
 if is_table_model_class(cls) and (not base_is_table or has_polymorphic):
 for rel_name, rel_info in cls.__sqlmodel_relationships__.items():
 if rel_info.sa_relationship:
 # There's a SQLAlchemy relationship declared, that takes precedence
Expand DownExpand Up@@ -737,10 +766,10 @@ def get_sqlalchemy_type(field: Any) -> Any:
 raise ValueError(f"{type_} has no matching SQLAlchemy type")


def get_column_from_field(field: Any) -> Column:
def get_column_from_field(field: Any) -> Column | MappedColumn: # type: ignore
 field_info = field
 sa_column = _get_sqlmodel_field_value(field_info, "sa_column", Undefined)
 if isinstance(sa_column, Column):
 if isinstance(sa_column, Column) or isinstance(sa_column, MappedColumn):
 return sa_column
 sa_type = get_sqlalchemy_type(field)
 primary_key = _get_sqlmodel_field_value(field_info, "primary_key", Undefined)
Expand DownExpand Up@@ -804,7 +833,6 @@ def get_column_from_field(field: Any) -> Column:
class SQLModel(BaseModel, metaclass=SQLModelMetaclass, registry=default_registry):
 # SQLAlchemy needs to set weakref(s), Pydantic will set the other slots values
 __slots__ = ("__weakref__",)
 __tablename__: ClassVar[str | Callable[..., str]]
 __sqlmodel_relationships__: ClassVar[builtins.dict[str, RelationshipProperty[Any]]]
 __name__: ClassVar[str]
 metadata: ClassVar[MetaData]
Expand DownExpand Up@@ -843,6 +871,14 @@ def __init__(__pydantic_self__, **data: Any) -> None:
 if finish_init.get():
 sqlmodel_init(self=__pydantic_self__, data=data)

 def _is_sqlmodel_relationship(self, name: str) -> bool:
 if name in self.__sqlmodel_relationships__:
 return True
 if not (is_table_model_class(self.__class__) and is_instrumented(self, name)):
 return False
 mapper = inspect(self.__class__, raiseerr=False)
 return mapper is not None and name in mapper.relationships

 def __setattr__(self, name: str, value: Any) -> None:
 if name in {"_sa_instance_state"}:
 self.__dict__[name] = value
Expand All@@ -853,7 +889,7 @@ def __setattr__(self, name: str, value: Any) -> None:
 set_attribute(self, name, value)
 # Set in Pydantic model to trigger possible validation changes, only for
 # non relationship values
 if name not in self.__sqlmodel_relationships__:
 if not self._is_sqlmodel_relationship(name):
 super().__setattr__(name, value)

 def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
Expand All@@ -864,10 +900,6 @@ def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
 if not (isinstance(k, str) and k.startswith("_sa_"))
 ]

 @declared_attr # type: ignore
 def __tablename__(cls) -> str:
 return cls.__name__.lower()

 @classmethod
 def model_validate( # ty: ignore[invalid-method-override]
 cls: type[_TSQLModel],
Expand Down
Empty file addedtests/test_polymorphic/__init__.py

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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Add support for polymorphism models
#1894
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61d6676

Add metaclass support for SQLAlchemy polymorphic models (joined-table…


ng-viet-hung Apr 28, 2026
c2851b2

Fix inherited relationship resolution in polymorphic subclass constru…


ng-viet-hung Apr 28, 2026
98c63d4

Add test suite for polymorphic inheritance


ng-viet-hung Apr 28, 2026
ff38e5c

Fix formatting


ng-viet-hung May 4, 2026

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105 changes: 102 additions & 3 deletions
sqlmodel/_compat.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,13 +1,14 @@
import sys
import types
from collections.abc import Generator
from collections.abc import Generator, Iterable
from contextlib import contextmanager
from contextvars import ContextVar
from dataclasses import dataclass
from typing import (
 TYPE_CHECKING,
 Annotated,
 Any,
 ClassVar,
 ForwardRef,
 TypeAlias,
 TypeVar,
Expand All@@ -26,6 +27,8 @@
from pydantic.fields import FieldInfo
from pydantic_core import PydanticUndefined as Undefined
from pydantic_core import PydanticUndefinedType as PydanticUndefinedType
from sqlalchemy import inspect
from sqlalchemy.orm import Mapper

BaseConfig = ConfigDict
UndefinedType = PydanticUndefinedType
Expand DownExpand Up@@ -68,6 +71,100 @@ def _is_union_type(t: Any) -> bool:
finish_init: ContextVar[bool] = ContextVar("finish_init", default=True)


def set_polymorphic_default_value(
 self_instance: _TSQLModel,
 values: dict[str, Any],
) -> bool:
 """By default, when init a model, pydantic will set the polymorphic_on
 value to field default value. But when inherit a model, the polymorphic_on
 should be set to polymorphic_identity value by default."""
 cls = type(self_instance)
 mapper = inspect(cls)
 ret = False
 if isinstance(mapper, Mapper):
 polymorphic_on = mapper.polymorphic_on
 if polymorphic_on is not None:
 polymorphic_property = mapper.get_property_by_column(polymorphic_on)
 field_info = get_model_fields(cls).get(polymorphic_property.key)
 if field_info:
 v = values.get(polymorphic_property.key)
 if mapper.inherits or v is None:
 setattr(
 self_instance,
 polymorphic_property.key,
 mapper.polymorphic_identity,
 )
 ret = True
 return ret


def _wrap_inherited_relationships_as_classvar(
 base: type,
 base_annotations: dict[str, Any],
 dict_used: dict[str, Any],
) -> None:
 """Convert inherited relationship annotations to ClassVar on the subclass.

 Pydantic would try to treat inherited SQLAlchemy relationship descriptors as plain
 fields, which fails at class-creation time. Tagging them ClassVar tells
 Pydantic to ignore them while SQLAlchemy continues to own the attribute.
 """
 if not hasattr(base, "__sqlmodel_relationships__"):
 return
 for k in base.__sqlmodel_relationships__:
 anno = base_annotations.get(k, Any)
 if get_origin(anno) is not ClassVar:
 dict_used["__annotations__"][k] = ClassVar[anno] # type: ignore[valid-type]


def _is_polymorphic_subclass(bases: tuple[type, ...]) -> bool:
 """Return True when any base class already defines a ``__tablename__``.

 This distinguishes a polymorphic subclass (which inherits from an existing
 table model) from a root table model that defines its own table.
 """
 return any(
 issubclass(base, BaseModel) and hasattr(base, "__tablename__") for base in bases
 )


def _collect_inherited_namespace(
 bases: tuple[type, ...],
 dict_used: dict[str, Any],
) -> dict[str, Any]:
 """Merge base-class fields/annotations into *dict_used* for polymorphic subclasses.

 Walks bases in method resolution order (reversed so the most-specific base wins),
 collecting Pydantic field definitions and annotations from every
 SQLModel table parent, and marking inherited relationships as ClassVar
 so Pydantic ignores them.
 """
 base_fields: dict[str, Any] = {}
 base_annotations: dict[str, Any] = {}
 for base in bases[::-1]:
 if not issubclass(base, BaseModel):
 continue
 base_model_fields = get_model_fields(base)
 base_fields.update(base_model_fields)
 for k in base_model_fields:
 if k in base.__annotations__:
 base_annotations[k] = base.__annotations__[k]
 _wrap_inherited_relationships_as_classvar(base, base_annotations, dict_used)
 base_annotations.update(dict_used["__annotations__"])
 dict_used["__annotations__"] = base_annotations
 base_fields.update(dict_used)
 return base_fields


def _relationship_keys(instance: _TSQLModel) -> Iterable[str]:
 mapper = inspect(type(instance), raiseerr=False)
 return (
 mapper.relationships.keys()
 if mapper is not None
 else instance.__sqlmodel_relationships__
 )


@contextmanager
def partial_init() -> Generator[None, None, None]:
 token = finish_init.set(False)
Expand DownExpand Up@@ -265,11 +362,13 @@ def sqlmodel_table_construct(
 object.__setattr__(self_instance, "__pydantic_private__", None)
 # SQLModel override, set relationships
 # Get and set any relationship objects
 for key in self_instance.__sqlmodel_relationships__:
 for key in _relationship_keys(self_instance):
 value = values.get(key, Undefined)
 if value is not Undefined:
 setattr(self_instance, key, value)
 # End SQLModel override
 # Override polymorphic_on default value
 set_polymorphic_default_value(self_instance, values)
 return self_instance


Expand DownExpand Up@@ -319,7 +418,7 @@ def sqlmodel_validate(
 object.__setattr__(new_obj, "__pydantic_fields_set__", fields_set)
 # Get and set any relationship objects
 if is_table_model_class(cls):
 for key in new_obj.__sqlmodel_relationships__:
 for key in _relationship_keys(new_obj):
 value = getattr(use_obj, key, Undefined)
 if value is not Undefined:
 setattr(new_obj, key, value)
Expand Down

58 changes: 45 additions & 13 deletions
sqlmodel/main.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -3,6 +3,7 @@
import builtins
import ipaddress
import uuid
import warnings
from collections.abc import Callable, Mapping, Sequence, Set
from dataclasses import dataclass
from datetime import date, datetime, time, timedelta
Expand DownExpand Up@@ -38,9 +39,10 @@
)
from sqlalchemy import Enum as sa_Enum
from sqlalchemy.orm import (
 InstrumentedAttribute,
 Mapped,
 MappedColumn,
 RelationshipProperty,
 declared_attr,
 registry,
 relationship,
)
Expand All@@ -59,6 +61,8 @@
 SQLModelConfig,
 Undefined,
 UndefinedType,
 _collect_inherited_namespace,
 _is_polymorphic_subclass,
 finish_init,
 get_annotations,
 get_field_metadata,
Expand DownExpand Up@@ -578,9 +582,22 @@ def __new__(
 config_kwargs = {
 key: kwargs[key] for key in kwargs.keys() & allowed_config_kwargs
 }
 new_cls = cast(
 "SQLModel", super().__new__(cls, name, bases, dict_used, **config_kwargs)
 )
 dict_used = _collect_inherited_namespace(bases, dict_used)
 if _is_polymorphic_subclass(bases):
 with warnings.catch_warnings():
 warnings.filterwarnings(
 "ignore",
 message="Field name .+ shadows an attribute in parent.+",
 )
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 else:
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 new_cls.__annotations__ = {
 **relationship_annotations,
 **pydantic_annotations,
Expand All@@ -598,9 +615,16 @@ def get_config(name: str) -> Any:

 config_table = get_config("table")
 if config_table is True:
 if new_cls.__name__ != "SQLModel" and not hasattr(new_cls, "__tablename__"):
 setattr(new_cls, "__tablename__", new_cls.__name__.lower()) # noqa: B010
 # If it was passed by kwargs, ensure it's also set in config
 new_cls.model_config["table"] = config_table
 for k, v in get_model_fields(new_cls).items():
 if (
 isinstance(getattr(new_cls, k, None), InstrumentedAttribute)
 and k not in class_dict
 ):
 continue
 col = get_column_from_field(v)
 setattr(new_cls, k, col)
 # Set a config flag to tell FastAPI that this should be read with a field
Expand DownExpand Up@@ -632,7 +656,12 @@ def __init__(
 # trying to create a new SQLAlchemy, for a new table, with the same name, that
 # triggers an error
 base_is_table = any(is_table_model_class(base) for base in bases)
 if is_table_model_class(cls) and not base_is_table:
 _mapper_args = dict_.get("__mapper_args__", {})
 has_polymorphic = (
 _mapper_args.get("polymorphic_identity") is not None
 or _mapper_args.get("polymorphic_abstract") is not None
 )
 if is_table_model_class(cls) and (not base_is_table or has_polymorphic):
 for rel_name, rel_info in cls.__sqlmodel_relationships__.items():
 if rel_info.sa_relationship:
 # There's a SQLAlchemy relationship declared, that takes precedence
Expand DownExpand Up@@ -737,10 +766,10 @@ def get_sqlalchemy_type(field: Any) -> Any:
 raise ValueError(f"{type_} has no matching SQLAlchemy type")


def get_column_from_field(field: Any) -> Column:
def get_column_from_field(field: Any) -> Column | MappedColumn: # type: ignore
 field_info = field
 sa_column = _get_sqlmodel_field_value(field_info, "sa_column", Undefined)
 if isinstance(sa_column, Column):
 if isinstance(sa_column, Column) or isinstance(sa_column, MappedColumn):
 return sa_column
 sa_type = get_sqlalchemy_type(field)
 primary_key = _get_sqlmodel_field_value(field_info, "primary_key", Undefined)
Expand DownExpand Up@@ -804,7 +833,6 @@ def get_column_from_field(field: Any) -> Column:
class SQLModel(BaseModel, metaclass=SQLModelMetaclass, registry=default_registry):
 # SQLAlchemy needs to set weakref(s), Pydantic will set the other slots values
 __slots__ = ("__weakref__",)
 __tablename__: ClassVar[str | Callable[..., str]]
 __sqlmodel_relationships__: ClassVar[builtins.dict[str, RelationshipProperty[Any]]]
 __name__: ClassVar[str]
 metadata: ClassVar[MetaData]
Expand DownExpand Up@@ -843,6 +871,14 @@ def __init__(__pydantic_self__, **data: Any) -> None:
 if finish_init.get():
 sqlmodel_init(self=__pydantic_self__, data=data)

 def _is_sqlmodel_relationship(self, name: str) -> bool:
 if name in self.__sqlmodel_relationships__:
 return True
 if not (is_table_model_class(self.__class__) and is_instrumented(self, name)):
 return False
 mapper = inspect(self.__class__, raiseerr=False)
 return mapper is not None and name in mapper.relationships

 def __setattr__(self, name: str, value: Any) -> None:
 if name in {"_sa_instance_state"}:
 self.__dict__[name] = value
Expand All@@ -853,7 +889,7 @@ def __setattr__(self, name: str, value: Any) -> None:
 set_attribute(self, name, value)
 # Set in Pydantic model to trigger possible validation changes, only for
 # non relationship values
 if name not in self.__sqlmodel_relationships__:
 if not self._is_sqlmodel_relationship(name):
 super().__setattr__(name, value)

 def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
Expand All@@ -864,10 +900,6 @@ def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
 if not (isinstance(k, str) and k.startswith("_sa_"))
 ]

 @declared_attr # type: ignore
 def __tablename__(cls) -> str:
 return cls.__name__.lower()

 @classmethod
 def model_validate( # ty: ignore[invalid-method-override]
 cls: type[_TSQLModel],
Expand Down
Empty file addedtests/test_polymorphic/__init__.py

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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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Add support for polymorphism models#1894

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 Open

viet-hung-ng
wants to merge
4
commits into

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Add support for polymorphism models
#1894
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61d6676

Add metaclass support for SQLAlchemy polymorphic models (joined-table…


ng-viet-hung Apr 28, 2026
c2851b2

Fix inherited relationship resolution in polymorphic subclass constru…


ng-viet-hung Apr 28, 2026
98c63d4

Add test suite for polymorphic inheritance


ng-viet-hung Apr 28, 2026
ff38e5c

Fix formatting


ng-viet-hung May 4, 2026

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105 changes: 102 additions & 3 deletions
sqlmodel/_compat.py

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -1,13 +1,14 @@
import sys
import types
from collections.abc import Generator
from collections.abc import Generator, Iterable
from contextlib import contextmanager
from contextvars import ContextVar
from dataclasses import dataclass
from typing import (
 TYPE_CHECKING,
 Annotated,
 Any,
 ClassVar,
 ForwardRef,
 TypeAlias,
 TypeVar,
Expand All@@ -26,6 +27,8 @@
from pydantic.fields import FieldInfo
from pydantic_core import PydanticUndefined as Undefined
from pydantic_core import PydanticUndefinedType as PydanticUndefinedType
from sqlalchemy import inspect
from sqlalchemy.orm import Mapper

BaseConfig = ConfigDict
UndefinedType = PydanticUndefinedType
Expand DownExpand Up@@ -68,6 +71,100 @@ def _is_union_type(t: Any) -> bool:
finish_init: ContextVar[bool] = ContextVar("finish_init", default=True)


def set_polymorphic_default_value(
 self_instance: _TSQLModel,
 values: dict[str, Any],
) -> bool:
 """By default, when init a model, pydantic will set the polymorphic_on
 value to field default value. But when inherit a model, the polymorphic_on
 should be set to polymorphic_identity value by default."""
 cls = type(self_instance)
 mapper = inspect(cls)
 ret = False
 if isinstance(mapper, Mapper):
 polymorphic_on = mapper.polymorphic_on
 if polymorphic_on is not None:
 polymorphic_property = mapper.get_property_by_column(polymorphic_on)
 field_info = get_model_fields(cls).get(polymorphic_property.key)
 if field_info:
 v = values.get(polymorphic_property.key)
 if mapper.inherits or v is None:
 setattr(
 self_instance,
 polymorphic_property.key,
 mapper.polymorphic_identity,
 )
 ret = True
 return ret


def _wrap_inherited_relationships_as_classvar(
 base: type,
 base_annotations: dict[str, Any],
 dict_used: dict[str, Any],
) -> None:
 """Convert inherited relationship annotations to ClassVar on the subclass.

 Pydantic would try to treat inherited SQLAlchemy relationship descriptors as plain
 fields, which fails at class-creation time. Tagging them ClassVar tells
 Pydantic to ignore them while SQLAlchemy continues to own the attribute.
 """
 if not hasattr(base, "__sqlmodel_relationships__"):
 return
 for k in base.__sqlmodel_relationships__:
 anno = base_annotations.get(k, Any)
 if get_origin(anno) is not ClassVar:
 dict_used["__annotations__"][k] = ClassVar[anno] # type: ignore[valid-type]


def _is_polymorphic_subclass(bases: tuple[type, ...]) -> bool:
 """Return True when any base class already defines a ``__tablename__``.

 This distinguishes a polymorphic subclass (which inherits from an existing
 table model) from a root table model that defines its own table.
 """
 return any(
 issubclass(base, BaseModel) and hasattr(base, "__tablename__") for base in bases
 )


def _collect_inherited_namespace(
 bases: tuple[type, ...],
 dict_used: dict[str, Any],
) -> dict[str, Any]:
 """Merge base-class fields/annotations into *dict_used* for polymorphic subclasses.

 Walks bases in method resolution order (reversed so the most-specific base wins),
 collecting Pydantic field definitions and annotations from every
 SQLModel table parent, and marking inherited relationships as ClassVar
 so Pydantic ignores them.
 """
 base_fields: dict[str, Any] = {}
 base_annotations: dict[str, Any] = {}
 for base in bases[::-1]:
 if not issubclass(base, BaseModel):
 continue
 base_model_fields = get_model_fields(base)
 base_fields.update(base_model_fields)
 for k in base_model_fields:
 if k in base.__annotations__:
 base_annotations[k] = base.__annotations__[k]
 _wrap_inherited_relationships_as_classvar(base, base_annotations, dict_used)
 base_annotations.update(dict_used["__annotations__"])
 dict_used["__annotations__"] = base_annotations
 base_fields.update(dict_used)
 return base_fields


def _relationship_keys(instance: _TSQLModel) -> Iterable[str]:
 mapper = inspect(type(instance), raiseerr=False)
 return (
 mapper.relationships.keys()
 if mapper is not None
 else instance.__sqlmodel_relationships__
 )


@contextmanager
def partial_init() -> Generator[None, None, None]:
 token = finish_init.set(False)
Expand DownExpand Up@@ -265,11 +362,13 @@ def sqlmodel_table_construct(
 object.__setattr__(self_instance, "__pydantic_private__", None)
 # SQLModel override, set relationships
 # Get and set any relationship objects
 for key in self_instance.__sqlmodel_relationships__:
 for key in _relationship_keys(self_instance):
 value = values.get(key, Undefined)
 if value is not Undefined:
 setattr(self_instance, key, value)
 # End SQLModel override
 # Override polymorphic_on default value
 set_polymorphic_default_value(self_instance, values)
 return self_instance


Expand DownExpand Up@@ -319,7 +418,7 @@ def sqlmodel_validate(
 object.__setattr__(new_obj, "__pydantic_fields_set__", fields_set)
 # Get and set any relationship objects
 if is_table_model_class(cls):
 for key in new_obj.__sqlmodel_relationships__:
 for key in _relationship_keys(new_obj):
 value = getattr(use_obj, key, Undefined)
 if value is not Undefined:
 setattr(new_obj, key, value)
Expand Down

58 changes: 45 additions & 13 deletions
sqlmodel/main.py

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Original file line numberDiff line numberDiff line change
Expand Up@@ -3,6 +3,7 @@
import builtins
import ipaddress
import uuid
import warnings
from collections.abc import Callable, Mapping, Sequence, Set
from dataclasses import dataclass
from datetime import date, datetime, time, timedelta
Expand DownExpand Up@@ -38,9 +39,10 @@
)
from sqlalchemy import Enum as sa_Enum
from sqlalchemy.orm import (
 InstrumentedAttribute,
 Mapped,
 MappedColumn,
 RelationshipProperty,
 declared_attr,
 registry,
 relationship,
)
Expand All@@ -59,6 +61,8 @@
 SQLModelConfig,
 Undefined,
 UndefinedType,
 _collect_inherited_namespace,
 _is_polymorphic_subclass,
 finish_init,
 get_annotations,
 get_field_metadata,
Expand DownExpand Up@@ -578,9 +582,22 @@ def __new__(
 config_kwargs = {
 key: kwargs[key] for key in kwargs.keys() & allowed_config_kwargs
 }
 new_cls = cast(
 "SQLModel", super().__new__(cls, name, bases, dict_used, **config_kwargs)
 )
 dict_used = _collect_inherited_namespace(bases, dict_used)
 if _is_polymorphic_subclass(bases):
 with warnings.catch_warnings():
 warnings.filterwarnings(
 "ignore",
 message="Field name .+ shadows an attribute in parent.+",
 )
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 else:
 new_cls = cast(
 "SQLModel",
 super().__new__(cls, name, bases, dict_used, **config_kwargs),
 )
 new_cls.__annotations__ = {
 **relationship_annotations,
 **pydantic_annotations,
Expand All@@ -598,9 +615,16 @@ def get_config(name: str) -> Any:

 config_table = get_config("table")
 if config_table is True:
 if new_cls.__name__ != "SQLModel" and not hasattr(new_cls, "__tablename__"):
 setattr(new_cls, "__tablename__", new_cls.__name__.lower()) # noqa: B010
 # If it was passed by kwargs, ensure it's also set in config
 new_cls.model_config["table"] = config_table
 for k, v in get_model_fields(new_cls).items():
 if (
 isinstance(getattr(new_cls, k, None), InstrumentedAttribute)
 and k not in class_dict
 ):
 continue
 col = get_column_from_field(v)
 setattr(new_cls, k, col)
 # Set a config flag to tell FastAPI that this should be read with a field
Expand DownExpand Up@@ -632,7 +656,12 @@ def __init__(
 # trying to create a new SQLAlchemy, for a new table, with the same name, that
 # triggers an error
 base_is_table = any(is_table_model_class(base) for base in bases)
 if is_table_model_class(cls) and not base_is_table:
 _mapper_args = dict_.get("__mapper_args__", {})
 has_polymorphic = (
 _mapper_args.get("polymorphic_identity") is not None
 or _mapper_args.get("polymorphic_abstract") is not None
 )
 if is_table_model_class(cls) and (not base_is_table or has_polymorphic):
 for rel_name, rel_info in cls.__sqlmodel_relationships__.items():
 if rel_info.sa_relationship:
 # There's a SQLAlchemy relationship declared, that takes precedence
Expand DownExpand Up@@ -737,10 +766,10 @@ def get_sqlalchemy_type(field: Any) -> Any:
 raise ValueError(f"{type_} has no matching SQLAlchemy type")


def get_column_from_field(field: Any) -> Column:
def get_column_from_field(field: Any) -> Column | MappedColumn: # type: ignore
 field_info = field
 sa_column = _get_sqlmodel_field_value(field_info, "sa_column", Undefined)
 if isinstance(sa_column, Column):
 if isinstance(sa_column, Column) or isinstance(sa_column, MappedColumn):
 return sa_column
 sa_type = get_sqlalchemy_type(field)
 primary_key = _get_sqlmodel_field_value(field_info, "primary_key", Undefined)
Expand DownExpand Up@@ -804,7 +833,6 @@ def get_column_from_field(field: Any) -> Column:
class SQLModel(BaseModel, metaclass=SQLModelMetaclass, registry=default_registry):
 # SQLAlchemy needs to set weakref(s), Pydantic will set the other slots values
 __slots__ = ("__weakref__",)
 __tablename__: ClassVar[str | Callable[..., str]]
 __sqlmodel_relationships__: ClassVar[builtins.dict[str, RelationshipProperty[Any]]]
 __name__: ClassVar[str]
 metadata: ClassVar[MetaData]
Expand DownExpand Up@@ -843,6 +871,14 @@ def __init__(__pydantic_self__, **data: Any) -> None:
 if finish_init.get():
 sqlmodel_init(self=__pydantic_self__, data=data)

 def _is_sqlmodel_relationship(self, name: str) -> bool:
 if name in self.__sqlmodel_relationships__:
 return True
 if not (is_table_model_class(self.__class__) and is_instrumented(self, name)):
 return False
 mapper = inspect(self.__class__, raiseerr=False)
 return mapper is not None and name in mapper.relationships

 def __setattr__(self, name: str, value: Any) -> None:
 if name in {"_sa_instance_state"}:
 self.__dict__[name] = value
Expand All@@ -853,7 +889,7 @@ def __setattr__(self, name: str, value: Any) -> None:
 set_attribute(self, name, value)
 # Set in Pydantic model to trigger possible validation changes, only for
 # non relationship values
 if name not in self.__sqlmodel_relationships__:
 if not self._is_sqlmodel_relationship(name):
 super().__setattr__(name, value)

 def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
Expand All@@ -864,10 +900,6 @@ def __repr_args__(self) -> Sequence[tuple[str | None, Any]]:
 if not (isinstance(k, str) and k.startswith("_sa_"))
 ]

 @declared_attr # type: ignore
 def __tablename__(cls) -> str:
 return cls.__name__.lower()

 @classmethod
 def model_validate( # ty: ignore[invalid-method-override]
 cls: type[_TSQLModel],
Expand Down
Empty file addedtests/test_polymorphic/__init__.py

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