Validate component properties #264 - March 1

.circleci/requirements/dev-requirements-py37.txt

@@ -14,3 +14,6 @@ requests[security]
 flake8
 pylint==2.2.2
 astroid==2.1.0
+Cerberus
+numpy
+pandas

.circleci/requirements/dev-requirements.txt

@@ -14,3 +14,6 @@ plotly==3.6.1
 requests[security]
 flake8
 pylint==1.9.4
+Cerberus
+numpy
+pandas

dash/_utils.py

@@ -84,3 +84,9 @@ def first(self, *names):
  value = self.get(name)
  if value:
  return value
+
+
+def _merge(x, y):
+ z = x.copy()
+ z.update(y)
+ return z

dash/dash.py

@@ -11,6 +11,7 @@
 import threading
 import warnings
 import re
+import pprint
 import logging
 
 from functools import wraps
@@ -25,6 +26,8 @@
 from .dependencies import Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component, ComponentRegistry
+from .development.validator import (DashValidator,
+ generate_validation_error_message)
 from . import exceptions
 from ._utils import AttributeDict as _AttributeDict
 from ._utils import interpolate_str as _interpolate
@@ -69,6 +72,27 @@
 _re_index_config_id = re.compile(r'id="_dash-config"')
 _re_index_scripts_id = re.compile(r'src=".*dash[-_]renderer.*"')
 
+_callback_validation_error_template = """
+A Dash Callback produced an invalid value!
+
+Dash tried to update the `{component_property}` prop of the
+`{component_name}` with id `{component_id}` by calling the
+`{callback_func_name}` function with `{args}` as arguments.
+
+This function call returned `{value}`, which did not pass
+validation tests for the `{component_name}` component.
+
+The expected schema for the `{component_property}` prop of the
+`{component_name}` component is:
+
+***************************************************************
+{component_schema}
+***************************************************************
+
+The errors in validation are as follows:
+
+"""
+
 
 # pylint: disable=too-many-instance-attributes
 # pylint: disable=too-many-arguments, too-many-locals
@@ -92,6 +116,7 @@ def __init__(
  external_scripts=None,
  external_stylesheets=None,
  suppress_callback_exceptions=None,
+ suppress_validation_exceptions=None,
  components_cache_max_age=None,
  **kwargs):
 
@@ -128,6 +153,10 @@ def __init__(
  'suppress_callback_exceptions',
  suppress_callback_exceptions, env_configs, False
  ),
+ 'suppress_validation_exceptions': _configs.get_config(
+ 'suppress_validation_exceptions',
+ suppress_validation_exceptions, env_configs, False
+ ),
  'routes_pathname_prefix': routes_pathname_prefix,
  'requests_pathname_prefix': requests_pathname_prefix,
  'include_assets_files': _configs.get_config(
@@ -765,7 +794,7 @@ def _validate_callback(self, output, inputs, state):
  output.component_id,
  output.component_property).replace(' ', ''))
 
- def _validate_callback_output(self, output_value, output):
+ def _debug_callback_serialization_error(self, output_value, output):
  valid = [str, dict, int, float, type(None), Component]
 
  def _raise_invalid(bad_val, outer_val, bad_type, path, index=None,
@@ -901,13 +930,11 @@ def callback(self, output, inputs=[], state=[]):
 
  def wrap_func(func):
  @wraps(func)
- def add_context(*args, **kwargs):
-
- output_value = func(*args, **kwargs)
+ def add_context(validated_output):
  response = {
  'response': {
  'props': {
- output.component_property: output_value
+ output.component_property: validated_output
  }
  }
  }
@@ -918,7 +945,10 @@ def add_context(*args, **kwargs):
  cls=plotly.utils.PlotlyJSONEncoder
  )
  except TypeError:
- self._validate_callback_output(output_value, output)
+ self._debug_callback_serialization_error(
+ validated_output,
+ output
+ )
  raise exceptions.InvalidCallbackReturnValue('''
  The callback for property `{property:s}`
  of component `{id:s}` returned a value
@@ -935,6 +965,7 @@ def add_context(*args, **kwargs):
  mimetype='application/json'
  )
 
+ self.callback_map[callback_id]['func'] = func
  self.callback_map[callback_id]['callback'] = add_context
 
  return add_context
@@ -978,7 +1009,62 @@ def dispatch(self):
  c['id'] == component_registration['id']
  ][0])
 
- return self.callback_map[target_id]['callback'](*args)
+ output_value = self.callback_map[target_id]['func'](*args)
+
+ # Only validate if we get required information from renderer
+ # and validation is not turned off by user
+ if not self.config.suppress_validation_exceptions and \
+ 'namespace' in output and 'type' in output:
+ # Python2.7 might make these keys and values unicode
+ namespace = str(output['namespace'])
+ component_type = str(output['type'])
+ component_id = str(output['id'])
+ component_property = str(output['property'])
+ callback_func_name = self.callback_map[target_id]['func'].__name__
+ self._validate_callback_output(namespace, component_type,
+ component_id, component_property,
+ callback_func_name,
+ args, output_value)
+
+ return self.callback_map[target_id]['callback'](output_value)
+
+ def _validate_callback_output(self, namespace, component_type,
+ component_id, component_property,
+ callback_func_name, args, value):
+ module = sys.modules[namespace]
+ component = getattr(module, component_type)
+ # pylint: disable=protected-access
+ validator = DashValidator({
+ component_property: component._schema.get(component_property, {})
+ })
+ valid = validator.validate({component_property: value})
+ if not valid:
+ error_message = _callback_validation_error_template.format(
+ component_property=component_property,
+ component_name=component.__name__,
+ component_id=component_id,
+ callback_func_name=callback_func_name,
+ args='({})'.format(", ".join(map(repr, args))),
+ value=value,
+ component_schema=pprint.pformat(
+ component._schema[component_property]
+ )
+ )
+
+ raise exceptions.CallbackOutputValidationError(
+ generate_validation_error_message(
+ validator.errors,
+ 0,
+ error_message
+ )
+ )
+ # Must also validate initialization of newly created components
+ if component_property == 'children':
+ if isinstance(value, Component):
+ value.validate()
+ for component in value.traverse():
+ if isinstance(component, Component):
+ component.validate()
 
  def _validate_layout(self):
  if self.layout is None:
@@ -995,6 +1081,11 @@ def _validate_layout(self):
 
  component_ids = {layout_id} if layout_id else set()
  for component in to_validate.traverse():
+ if (
+ not self.config.suppress_validation_exceptions and
+ isinstance(component, Component)
+ ):
+ component.validate()
  component_id = getattr(component, 'id', None)
  if component_id and component_id in component_ids:
  raise exceptions.DuplicateIdError(
@@ -1292,6 +1383,10 @@ def run_server(self,
  dev_tools_silence_routes_logging,
  )
 
+ if not debug:
+ # Do not throw validation exceptions in production.
+ self.config.suppress_validation_exceptions = True
+
  if self._dev_tools.silence_routes_logging:
  # Since it's silenced, the address don't show anymore.
  host = flask_run_options.get('host', '127.0.0.1')

dash/development/_py_components_generation.py

@@ -2,13 +2,16 @@
 import copy
 import os
 
-from dash.development.base_component import _explicitize_args
+from dash.development.base_component import (
+ _explicitize_args,
+ generate_property_schema
+)
 from dash.exceptions import NonExistentEventException
 from ._all_keywords import python_keywords
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(typename, props, description, namespace):
  """
  Dynamically generate class strings to have nicely formatted docstrings,
@@ -43,8 +46,12 @@ def generate_class_string(typename, props, description, namespace):
  # it to be `null` or whether that was just the default value.
  # The solution might be to deal with default values better although
  # not all component authors will supply those.
- c = '''class {typename}(Component):
+ c = '''\
+schema = {schema}
+
+class {typename}(Component):
  """{docstring}"""
+ _schema = schema
  @_explicitize_args
  def __init__(self, {default_argtext}):
  self._prop_names = {list_of_valid_keys}
@@ -55,7 +62,6 @@ def __init__(self, {default_argtext}):
  self.available_properties = {list_of_valid_keys}
  self.available_wildcard_properties =\
  {list_of_valid_wildcard_attr_prefixes}
-
  _explicit_args = kwargs.pop('_explicit_args')
  _locals = locals()
  _locals.update(kwargs) # For wildcard attrs
@@ -85,7 +91,7 @@ def __init__(self, {default_argtext}):
  default_argtext = "children=None, "
  argtext = 'children=children, **args'
  else:
- default_argtext = ""
+ default_argtext = ''
  argtext = '**args'
  default_argtext += ", ".join(
  [('{:s}=Component.REQUIRED'.format(p)
@@ -97,6 +103,10 @@ def __init__(self, {default_argtext}):
  p != 'setProps'] + ["**kwargs"]
  )
  required_args = required_props(props)
+ schema = {
+ k: generate_property_schema(v)
+ for k, v in props.items() if not k.endswith("-*")
+ }
  return c.format(
  typename=typename,
  namespace=namespace,
@@ -106,7 +116,8 @@ def __init__(self, {default_argtext}):
  docstring=docstring,
  default_argtext=default_argtext,
  argtext=argtext,
- required_props=required_args
+ required_props=required_args,
+ schema=schema
  )
 
 

.circleci/requirements/dev-requirements-py37.txt

@@ -14,3 +14,6 @@ requests[security]
 flake8
 pylint==2.2.2
 astroid==2.1.0
+Cerberus
+numpy
+pandas

.circleci/requirements/dev-requirements.txt

@@ -14,3 +14,6 @@ plotly==3.6.1
 requests[security]
 flake8
 pylint==1.9.4
+Cerberus
+numpy
+pandas

dash/_utils.py

@@ -84,3 +84,9 @@ def first(self, *names):
  value = self.get(name)
  if value:
  return value
+
+
+def _merge(x, y):
+ z = x.copy()
+ z.update(y)
+ return z

dash/dash.py

@@ -11,6 +11,7 @@
 import threading
 import warnings
 import re
+import pprint
 import logging
 
 from functools import wraps
@@ -25,6 +26,8 @@
 from .dependencies import Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component, ComponentRegistry
+from .development.validator import (DashValidator,
+ generate_validation_error_message)
 from . import exceptions
 from ._utils import AttributeDict as _AttributeDict
 from ._utils import interpolate_str as _interpolate
@@ -69,6 +72,27 @@
 _re_index_config_id = re.compile(r'id="_dash-config"')
 _re_index_scripts_id = re.compile(r'src=".*dash[-_]renderer.*"')
 
+_callback_validation_error_template = """
+A Dash Callback produced an invalid value!
+
+Dash tried to update the `{component_property}` prop of the
+`{component_name}` with id `{component_id}` by calling the
+`{callback_func_name}` function with `{args}` as arguments.
+
+This function call returned `{value}`, which did not pass
+validation tests for the `{component_name}` component.
+
+The expected schema for the `{component_property}` prop of the
+`{component_name}` component is:
+
+***************************************************************
+{component_schema}
+***************************************************************
+
+The errors in validation are as follows:
+
+"""
+
 
 # pylint: disable=too-many-instance-attributes
 # pylint: disable=too-many-arguments, too-many-locals
@@ -92,6 +116,7 @@ def __init__(
  external_scripts=None,
  external_stylesheets=None,
  suppress_callback_exceptions=None,
+ suppress_validation_exceptions=None,
  components_cache_max_age=None,
  **kwargs):
 
@@ -128,6 +153,10 @@ def __init__(
  'suppress_callback_exceptions',
  suppress_callback_exceptions, env_configs, False
  ),
+ 'suppress_validation_exceptions': _configs.get_config(
+ 'suppress_validation_exceptions',
+ suppress_validation_exceptions, env_configs, False
+ ),
  'routes_pathname_prefix': routes_pathname_prefix,
  'requests_pathname_prefix': requests_pathname_prefix,
  'include_assets_files': _configs.get_config(
@@ -765,7 +794,7 @@ def _validate_callback(self, output, inputs, state):
  output.component_id,
  output.component_property).replace(' ', ''))
 
- def _validate_callback_output(self, output_value, output):
+ def _debug_callback_serialization_error(self, output_value, output):
  valid = [str, dict, int, float, type(None), Component]
 
  def _raise_invalid(bad_val, outer_val, bad_type, path, index=None,
@@ -901,13 +930,11 @@ def callback(self, output, inputs=[], state=[]):
 
  def wrap_func(func):
  @wraps(func)
- def add_context(*args, **kwargs):
-
- output_value = func(*args, **kwargs)
+ def add_context(validated_output):
  response = {
  'response': {
  'props': {
- output.component_property: output_value
+ output.component_property: validated_output
  }
  }
  }
@@ -918,7 +945,10 @@ def add_context(*args, **kwargs):
  cls=plotly.utils.PlotlyJSONEncoder
  )
  except TypeError:
- self._validate_callback_output(output_value, output)
+ self._debug_callback_serialization_error(
+ validated_output,
+ output
+ )
  raise exceptions.InvalidCallbackReturnValue('''
  The callback for property `{property:s}`
  of component `{id:s}` returned a value
@@ -935,6 +965,7 @@ def add_context(*args, **kwargs):
  mimetype='application/json'
  )
 
+ self.callback_map[callback_id]['func'] = func
  self.callback_map[callback_id]['callback'] = add_context
 
  return add_context
@@ -978,7 +1009,62 @@ def dispatch(self):
  c['id'] == component_registration['id']
  ][0])
 
- return self.callback_map[target_id]['callback'](*args)
+ output_value = self.callback_map[target_id]['func'](*args)
+
+ # Only validate if we get required information from renderer
+ # and validation is not turned off by user
+ if not self.config.suppress_validation_exceptions and \
+ 'namespace' in output and 'type' in output:
+ # Python2.7 might make these keys and values unicode
+ namespace = str(output['namespace'])
+ component_type = str(output['type'])
+ component_id = str(output['id'])
+ component_property = str(output['property'])
+ callback_func_name = self.callback_map[target_id]['func'].__name__
+ self._validate_callback_output(namespace, component_type,
+ component_id, component_property,
+ callback_func_name,
+ args, output_value)
+
+ return self.callback_map[target_id]['callback'](output_value)
+
+ def _validate_callback_output(self, namespace, component_type,
+ component_id, component_property,
+ callback_func_name, args, value):
+ module = sys.modules[namespace]
+ component = getattr(module, component_type)
+ # pylint: disable=protected-access
+ validator = DashValidator({
+ component_property: component._schema.get(component_property, {})
+ })
+ valid = validator.validate({component_property: value})
+ if not valid:
+ error_message = _callback_validation_error_template.format(
+ component_property=component_property,
+ component_name=component.__name__,
+ component_id=component_id,
+ callback_func_name=callback_func_name,
+ args='({})'.format(", ".join(map(repr, args))),
+ value=value,
+ component_schema=pprint.pformat(
+ component._schema[component_property]
+ )
+ )
+
+ raise exceptions.CallbackOutputValidationError(
+ generate_validation_error_message(
+ validator.errors,
+ 0,
+ error_message
+ )
+ )
+ # Must also validate initialization of newly created components
+ if component_property == 'children':
+ if isinstance(value, Component):
+ value.validate()
+ for component in value.traverse():
+ if isinstance(component, Component):
+ component.validate()
 
  def _validate_layout(self):
  if self.layout is None:
@@ -995,6 +1081,11 @@ def _validate_layout(self):
 
  component_ids = {layout_id} if layout_id else set()
  for component in to_validate.traverse():
+ if (
+ not self.config.suppress_validation_exceptions and
+ isinstance(component, Component)
+ ):
+ component.validate()
  component_id = getattr(component, 'id', None)
  if component_id and component_id in component_ids:
  raise exceptions.DuplicateIdError(
@@ -1292,6 +1383,10 @@ def run_server(self,
  dev_tools_silence_routes_logging,
  )
 
+ if not debug:
+ # Do not throw validation exceptions in production.
+ self.config.suppress_validation_exceptions = True
+
  if self._dev_tools.silence_routes_logging:
  # Since it's silenced, the address don't show anymore.
  host = flask_run_options.get('host', '127.0.0.1')

dash/development/_py_components_generation.py

@@ -2,13 +2,16 @@
 import copy
 import os
 
-from dash.development.base_component import _explicitize_args
+from dash.development.base_component import (
+ _explicitize_args,
+ generate_property_schema
+)
 from dash.exceptions import NonExistentEventException
 from ._all_keywords import python_keywords
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(typename, props, description, namespace):
  """
  Dynamically generate class strings to have nicely formatted docstrings,
@@ -43,8 +46,12 @@ def generate_class_string(typename, props, description, namespace):
  # it to be `null` or whether that was just the default value.
  # The solution might be to deal with default values better although
  # not all component authors will supply those.
- c = '''class {typename}(Component):
+ c = '''\
+schema = {schema}
+
+class {typename}(Component):
  """{docstring}"""
+ _schema = schema
  @_explicitize_args
  def __init__(self, {default_argtext}):
  self._prop_names = {list_of_valid_keys}
@@ -55,7 +62,6 @@ def __init__(self, {default_argtext}):
  self.available_properties = {list_of_valid_keys}
  self.available_wildcard_properties =\
  {list_of_valid_wildcard_attr_prefixes}
-
  _explicit_args = kwargs.pop('_explicit_args')
  _locals = locals()
  _locals.update(kwargs) # For wildcard attrs
@@ -85,7 +91,7 @@ def __init__(self, {default_argtext}):
  default_argtext = "children=None, "
  argtext = 'children=children, **args'
  else:
- default_argtext = ""
+ default_argtext = ''
  argtext = '**args'
  default_argtext += ", ".join(
  [('{:s}=Component.REQUIRED'.format(p)
@@ -97,6 +103,10 @@ def __init__(self, {default_argtext}):
  p != 'setProps'] + ["**kwargs"]
  )
  required_args = required_props(props)
+ schema = {
+ k: generate_property_schema(v)
+ for k, v in props.items() if not k.endswith("-*")
+ }
  return c.format(
  typename=typename,
  namespace=namespace,
@@ -106,7 +116,8 @@ def __init__(self, {default_argtext}):
  docstring=docstring,
  default_argtext=default_argtext,
  argtext=argtext,
- required_props=required_args
+ required_props=required_args,
+ schema=schema
  )
 
 

.circleci/requirements/dev-requirements-py37.txt

@@ -14,3 +14,6 @@ requests[security]
 flake8
 pylint==2.2.2
 astroid==2.1.0
+Cerberus
+numpy
+pandas

.circleci/requirements/dev-requirements.txt

@@ -14,3 +14,6 @@ plotly==3.6.1
 requests[security]
 flake8
 pylint==1.9.4
+Cerberus
+numpy
+pandas

dash/_utils.py

@@ -84,3 +84,9 @@ def first(self, *names):
  value = self.get(name)
  if value:
  return value
+
+
+def _merge(x, y):
+ z = x.copy()
+ z.update(y)
+ return z

dash/dash.py

@@ -11,6 +11,7 @@
 import threading
 import warnings
 import re
+import pprint
 import logging
 
 from functools import wraps
@@ -25,6 +26,8 @@
 from .dependencies import Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component, ComponentRegistry
+from .development.validator import (DashValidator,
+ generate_validation_error_message)
 from . import exceptions
 from ._utils import AttributeDict as _AttributeDict
 from ._utils import interpolate_str as _interpolate
@@ -69,6 +72,27 @@
 _re_index_config_id = re.compile(r'id="_dash-config"')
 _re_index_scripts_id = re.compile(r'src=".*dash[-_]renderer.*"')
 
+_callback_validation_error_template = """
+A Dash Callback produced an invalid value!
+
+Dash tried to update the `{component_property}` prop of the
+`{component_name}` with id `{component_id}` by calling the
+`{callback_func_name}` function with `{args}` as arguments.
+
+This function call returned `{value}`, which did not pass
+validation tests for the `{component_name}` component.
+
+The expected schema for the `{component_property}` prop of the
+`{component_name}` component is:
+
+***************************************************************
+{component_schema}
+***************************************************************
+
+The errors in validation are as follows:
+
+"""
+
 
 # pylint: disable=too-many-instance-attributes
 # pylint: disable=too-many-arguments, too-many-locals
@@ -92,6 +116,7 @@ def __init__(
  external_scripts=None,
  external_stylesheets=None,
  suppress_callback_exceptions=None,
+ suppress_validation_exceptions=None,
  components_cache_max_age=None,
  **kwargs):
 
@@ -128,6 +153,10 @@ def __init__(
  'suppress_callback_exceptions',
  suppress_callback_exceptions, env_configs, False
  ),
+ 'suppress_validation_exceptions': _configs.get_config(
+ 'suppress_validation_exceptions',
+ suppress_validation_exceptions, env_configs, False
+ ),
  'routes_pathname_prefix': routes_pathname_prefix,
  'requests_pathname_prefix': requests_pathname_prefix,
  'include_assets_files': _configs.get_config(
@@ -765,7 +794,7 @@ def _validate_callback(self, output, inputs, state):
  output.component_id,
  output.component_property).replace(' ', ''))
 
- def _validate_callback_output(self, output_value, output):
+ def _debug_callback_serialization_error(self, output_value, output):
  valid = [str, dict, int, float, type(None), Component]
 
  def _raise_invalid(bad_val, outer_val, bad_type, path, index=None,
@@ -901,13 +930,11 @@ def callback(self, output, inputs=[], state=[]):
 
  def wrap_func(func):
  @wraps(func)
- def add_context(*args, **kwargs):
-
- output_value = func(*args, **kwargs)
+ def add_context(validated_output):
  response = {
  'response': {
  'props': {
- output.component_property: output_value
+ output.component_property: validated_output
  }
  }
  }
@@ -918,7 +945,10 @@ def add_context(*args, **kwargs):
  cls=plotly.utils.PlotlyJSONEncoder
  )
  except TypeError:
- self._validate_callback_output(output_value, output)
+ self._debug_callback_serialization_error(
+ validated_output,
+ output
+ )
  raise exceptions.InvalidCallbackReturnValue('''
  The callback for property `{property:s}`
  of component `{id:s}` returned a value
@@ -935,6 +965,7 @@ def add_context(*args, **kwargs):
  mimetype='application/json'
  )
 
+ self.callback_map[callback_id]['func'] = func
  self.callback_map[callback_id]['callback'] = add_context
 
  return add_context
@@ -978,7 +1009,62 @@ def dispatch(self):
  c['id'] == component_registration['id']
  ][0])
 
- return self.callback_map[target_id]['callback'](*args)
+ output_value = self.callback_map[target_id]['func'](*args)
+
+ # Only validate if we get required information from renderer
+ # and validation is not turned off by user
+ if not self.config.suppress_validation_exceptions and \
+ 'namespace' in output and 'type' in output:
+ # Python2.7 might make these keys and values unicode
+ namespace = str(output['namespace'])
+ component_type = str(output['type'])
+ component_id = str(output['id'])
+ component_property = str(output['property'])
+ callback_func_name = self.callback_map[target_id]['func'].__name__
+ self._validate_callback_output(namespace, component_type,
+ component_id, component_property,
+ callback_func_name,
+ args, output_value)
+
+ return self.callback_map[target_id]['callback'](output_value)
+
+ def _validate_callback_output(self, namespace, component_type,
+ component_id, component_property,
+ callback_func_name, args, value):
+ module = sys.modules[namespace]
+ component = getattr(module, component_type)
+ # pylint: disable=protected-access
+ validator = DashValidator({
+ component_property: component._schema.get(component_property, {})
+ })
+ valid = validator.validate({component_property: value})
+ if not valid:
+ error_message = _callback_validation_error_template.format(
+ component_property=component_property,
+ component_name=component.__name__,
+ component_id=component_id,
+ callback_func_name=callback_func_name,
+ args='({})'.format(", ".join(map(repr, args))),
+ value=value,
+ component_schema=pprint.pformat(
+ component._schema[component_property]
+ )
+ )
+
+ raise exceptions.CallbackOutputValidationError(
+ generate_validation_error_message(
+ validator.errors,
+ 0,
+ error_message
+ )
+ )
+ # Must also validate initialization of newly created components
+ if component_property == 'children':
+ if isinstance(value, Component):
+ value.validate()
+ for component in value.traverse():
+ if isinstance(component, Component):
+ component.validate()
 
  def _validate_layout(self):
  if self.layout is None:
@@ -995,6 +1081,11 @@ def _validate_layout(self):
 
  component_ids = {layout_id} if layout_id else set()
  for component in to_validate.traverse():
+ if (
+ not self.config.suppress_validation_exceptions and
+ isinstance(component, Component)
+ ):
+ component.validate()
  component_id = getattr(component, 'id', None)
  if component_id and component_id in component_ids:
  raise exceptions.DuplicateIdError(
@@ -1292,6 +1383,10 @@ def run_server(self,
  dev_tools_silence_routes_logging,
  )
 
+ if not debug:
+ # Do not throw validation exceptions in production.
+ self.config.suppress_validation_exceptions = True
+
  if self._dev_tools.silence_routes_logging:
  # Since it's silenced, the address don't show anymore.
  host = flask_run_options.get('host', '127.0.0.1')

dash/development/_py_components_generation.py

@@ -2,13 +2,16 @@
 import copy
 import os
 
-from dash.development.base_component import _explicitize_args
+from dash.development.base_component import (
+ _explicitize_args,
+ generate_property_schema
+)
 from dash.exceptions import NonExistentEventException
 from ._all_keywords import python_keywords
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(typename, props, description, namespace):
  """
  Dynamically generate class strings to have nicely formatted docstrings,
@@ -43,8 +46,12 @@ def generate_class_string(typename, props, description, namespace):
  # it to be `null` or whether that was just the default value.
  # The solution might be to deal with default values better although
  # not all component authors will supply those.
- c = '''class {typename}(Component):
+ c = '''\
+schema = {schema}
+
+class {typename}(Component):
  """{docstring}"""
+ _schema = schema
  @_explicitize_args
  def __init__(self, {default_argtext}):
  self._prop_names = {list_of_valid_keys}
@@ -55,7 +62,6 @@ def __init__(self, {default_argtext}):
  self.available_properties = {list_of_valid_keys}
  self.available_wildcard_properties =\
  {list_of_valid_wildcard_attr_prefixes}
-
  _explicit_args = kwargs.pop('_explicit_args')
  _locals = locals()
  _locals.update(kwargs) # For wildcard attrs
@@ -85,7 +91,7 @@ def __init__(self, {default_argtext}):
  default_argtext = "children=None, "
  argtext = 'children=children, **args'
  else:
- default_argtext = ""
+ default_argtext = ''
  argtext = '**args'
  default_argtext += ", ".join(
  [('{:s}=Component.REQUIRED'.format(p)
@@ -97,6 +103,10 @@ def __init__(self, {default_argtext}):
  p != 'setProps'] + ["**kwargs"]
  )
  required_args = required_props(props)
+ schema = {
+ k: generate_property_schema(v)
+ for k, v in props.items() if not k.endswith("-*")
+ }
  return c.format(
  typename=typename,
  namespace=namespace,
@@ -106,7 +116,8 @@ def __init__(self, {default_argtext}):
  docstring=docstring,
  default_argtext=default_argtext,
  argtext=argtext,
- required_props=required_args
+ required_props=required_args,
+ schema=schema
  )
 
 

.circleci/requirements/dev-requirements-py37.txt

@@ -14,3 +14,6 @@ requests[security]
 flake8
 pylint==2.2.2
 astroid==2.1.0
+Cerberus
+numpy
+pandas

.circleci/requirements/dev-requirements.txt

@@ -14,3 +14,6 @@ plotly==3.6.1
 requests[security]
 flake8
 pylint==1.9.4
+Cerberus
+numpy
+pandas

dash/_utils.py

@@ -84,3 +84,9 @@ def first(self, *names):
  value = self.get(name)
  if value:
  return value
+
+
+def _merge(x, y):
+ z = x.copy()
+ z.update(y)
+ return z

dash/dash.py

@@ -11,6 +11,7 @@
 import threading
 import warnings
 import re
+import pprint
 import logging
 
 from functools import wraps
@@ -25,6 +26,8 @@
 from .dependencies import Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component, ComponentRegistry
+from .development.validator import (DashValidator,
+ generate_validation_error_message)
 from . import exceptions
 from ._utils import AttributeDict as _AttributeDict
 from ._utils import interpolate_str as _interpolate
@@ -69,6 +72,27 @@
 _re_index_config_id = re.compile(r'id="_dash-config"')
 _re_index_scripts_id = re.compile(r'src=".*dash[-_]renderer.*"')
 
+_callback_validation_error_template = """
+A Dash Callback produced an invalid value!
+
+Dash tried to update the `{component_property}` prop of the
+`{component_name}` with id `{component_id}` by calling the
+`{callback_func_name}` function with `{args}` as arguments.
+
+This function call returned `{value}`, which did not pass
+validation tests for the `{component_name}` component.
+
+The expected schema for the `{component_property}` prop of the
+`{component_name}` component is:
+
+***************************************************************
+{component_schema}
+***************************************************************
+
+The errors in validation are as follows:
+
+"""
+
 
 # pylint: disable=too-many-instance-attributes
 # pylint: disable=too-many-arguments, too-many-locals
@@ -92,6 +116,7 @@ def __init__(
  external_scripts=None,
  external_stylesheets=None,
  suppress_callback_exceptions=None,
+ suppress_validation_exceptions=None,
  components_cache_max_age=None,
  **kwargs):
 
@@ -128,6 +153,10 @@ def __init__(
  'suppress_callback_exceptions',
  suppress_callback_exceptions, env_configs, False
  ),
+ 'suppress_validation_exceptions': _configs.get_config(
+ 'suppress_validation_exceptions',
+ suppress_validation_exceptions, env_configs, False
+ ),
  'routes_pathname_prefix': routes_pathname_prefix,
  'requests_pathname_prefix': requests_pathname_prefix,
  'include_assets_files': _configs.get_config(
@@ -765,7 +794,7 @@ def _validate_callback(self, output, inputs, state):
  output.component_id,
  output.component_property).replace(' ', ''))
 
- def _validate_callback_output(self, output_value, output):
+ def _debug_callback_serialization_error(self, output_value, output):
  valid = [str, dict, int, float, type(None), Component]
 
  def _raise_invalid(bad_val, outer_val, bad_type, path, index=None,
@@ -901,13 +930,11 @@ def callback(self, output, inputs=[], state=[]):
 
  def wrap_func(func):
  @wraps(func)
- def add_context(*args, **kwargs):
-
- output_value = func(*args, **kwargs)
+ def add_context(validated_output):
  response = {
  'response': {
  'props': {
- output.component_property: output_value
+ output.component_property: validated_output
  }
  }
  }
@@ -918,7 +945,10 @@ def add_context(*args, **kwargs):
  cls=plotly.utils.PlotlyJSONEncoder
  )
  except TypeError:
- self._validate_callback_output(output_value, output)
+ self._debug_callback_serialization_error(
+ validated_output,
+ output
+ )
  raise exceptions.InvalidCallbackReturnValue('''
  The callback for property `{property:s}`
  of component `{id:s}` returned a value
@@ -935,6 +965,7 @@ def add_context(*args, **kwargs):
  mimetype='application/json'
  )
 
+ self.callback_map[callback_id]['func'] = func
  self.callback_map[callback_id]['callback'] = add_context
 
  return add_context
@@ -978,7 +1009,62 @@ def dispatch(self):
  c['id'] == component_registration['id']
  ][0])
 
- return self.callback_map[target_id]['callback'](*args)
+ output_value = self.callback_map[target_id]['func'](*args)
+
+ # Only validate if we get required information from renderer
+ # and validation is not turned off by user
+ if not self.config.suppress_validation_exceptions and \
+ 'namespace' in output and 'type' in output:
+ # Python2.7 might make these keys and values unicode
+ namespace = str(output['namespace'])
+ component_type = str(output['type'])
+ component_id = str(output['id'])
+ component_property = str(output['property'])
+ callback_func_name = self.callback_map[target_id]['func'].__name__
+ self._validate_callback_output(namespace, component_type,
+ component_id, component_property,
+ callback_func_name,
+ args, output_value)
+
+ return self.callback_map[target_id]['callback'](output_value)
+
+ def _validate_callback_output(self, namespace, component_type,
+ component_id, component_property,
+ callback_func_name, args, value):
+ module = sys.modules[namespace]
+ component = getattr(module, component_type)
+ # pylint: disable=protected-access
+ validator = DashValidator({
+ component_property: component._schema.get(component_property, {})
+ })
+ valid = validator.validate({component_property: value})
+ if not valid:
+ error_message = _callback_validation_error_template.format(
+ component_property=component_property,
+ component_name=component.__name__,
+ component_id=component_id,
+ callback_func_name=callback_func_name,
+ args='({})'.format(", ".join(map(repr, args))),
+ value=value,
+ component_schema=pprint.pformat(
+ component._schema[component_property]
+ )
+ )
+
+ raise exceptions.CallbackOutputValidationError(
+ generate_validation_error_message(
+ validator.errors,
+ 0,
+ error_message
+ )
+ )
+ # Must also validate initialization of newly created components
+ if component_property == 'children':
+ if isinstance(value, Component):
+ value.validate()
+ for component in value.traverse():
+ if isinstance(component, Component):
+ component.validate()
 
  def _validate_layout(self):
  if self.layout is None:
@@ -995,6 +1081,11 @@ def _validate_layout(self):
 
  component_ids = {layout_id} if layout_id else set()
  for component in to_validate.traverse():
+ if (
+ not self.config.suppress_validation_exceptions and
+ isinstance(component, Component)
+ ):
+ component.validate()
  component_id = getattr(component, 'id', None)
  if component_id and component_id in component_ids:
  raise exceptions.DuplicateIdError(
@@ -1292,6 +1383,10 @@ def run_server(self,
  dev_tools_silence_routes_logging,
  )
 
+ if not debug:
+ # Do not throw validation exceptions in production.
+ self.config.suppress_validation_exceptions = True
+
  if self._dev_tools.silence_routes_logging:
  # Since it's silenced, the address don't show anymore.
  host = flask_run_options.get('host', '127.0.0.1')

dash/development/_py_components_generation.py

@@ -2,13 +2,16 @@
 import copy
 import os
 
-from dash.development.base_component import _explicitize_args
+from dash.development.base_component import (
+ _explicitize_args,
+ generate_property_schema
+)
 from dash.exceptions import NonExistentEventException
 from ._all_keywords import python_keywords
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(typename, props, description, namespace):
  """
  Dynamically generate class strings to have nicely formatted docstrings,
@@ -43,8 +46,12 @@ def generate_class_string(typename, props, description, namespace):
  # it to be `null` or whether that was just the default value.
  # The solution might be to deal with default values better although
  # not all component authors will supply those.
- c = '''class {typename}(Component):
+ c = '''\
+schema = {schema}
+
+class {typename}(Component):
  """{docstring}"""
+ _schema = schema
  @_explicitize_args
  def __init__(self, {default_argtext}):
  self._prop_names = {list_of_valid_keys}
@@ -55,7 +62,6 @@ def __init__(self, {default_argtext}):
  self.available_properties = {list_of_valid_keys}
  self.available_wildcard_properties =\
  {list_of_valid_wildcard_attr_prefixes}
-
  _explicit_args = kwargs.pop('_explicit_args')
  _locals = locals()
  _locals.update(kwargs) # For wildcard attrs
@@ -85,7 +91,7 @@ def __init__(self, {default_argtext}):
  default_argtext = "children=None, "
  argtext = 'children=children, **args'
  else:
- default_argtext = ""
+ default_argtext = ''
  argtext = '**args'
  default_argtext += ", ".join(
  [('{:s}=Component.REQUIRED'.format(p)
@@ -97,6 +103,10 @@ def __init__(self, {default_argtext}):
  p != 'setProps'] + ["**kwargs"]
  )
  required_args = required_props(props)
+ schema = {
+ k: generate_property_schema(v)
+ for k, v in props.items() if not k.endswith("-*")
+ }
  return c.format(
  typename=typename,
  namespace=namespace,
@@ -106,7 +116,8 @@ def __init__(self, {default_argtext}):
  docstring=docstring,
  default_argtext=default_argtext,
  argtext=argtext,
- required_props=required_args
+ required_props=required_args,
+ schema=schema
  )
 
 

.circleci/requirements/dev-requirements-py37.txt

@@ -14,3 +14,6 @@ requests[security]
 flake8
 pylint==2.2.2
 astroid==2.1.0
+Cerberus
+numpy
+pandas

.circleci/requirements/dev-requirements.txt

@@ -14,3 +14,6 @@ plotly==3.6.1
 requests[security]
 flake8
 pylint==1.9.4
+Cerberus
+numpy
+pandas

dash/_utils.py

@@ -84,3 +84,9 @@ def first(self, *names):
  value = self.get(name)
  if value:
  return value
+
+
+def _merge(x, y):
+ z = x.copy()
+ z.update(y)
+ return z

dash/dash.py

@@ -11,6 +11,7 @@
 import threading
 import warnings
 import re
+import pprint
 import logging
 
 from functools import wraps
@@ -25,6 +26,8 @@
 from .dependencies import Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component, ComponentRegistry
+from .development.validator import (DashValidator,
+ generate_validation_error_message)
 from . import exceptions
 from ._utils import AttributeDict as _AttributeDict
 from ._utils import interpolate_str as _interpolate
@@ -69,6 +72,27 @@
 _re_index_config_id = re.compile(r'id="_dash-config"')
 _re_index_scripts_id = re.compile(r'src=".*dash[-_]renderer.*"')
 
+_callback_validation_error_template = """
+A Dash Callback produced an invalid value!
+
+Dash tried to update the `{component_property}` prop of the
+`{component_name}` with id `{component_id}` by calling the
+`{callback_func_name}` function with `{args}` as arguments.
+
+This function call returned `{value}`, which did not pass
+validation tests for the `{component_name}` component.
+
+The expected schema for the `{component_property}` prop of the
+`{component_name}` component is:
+
+***************************************************************
+{component_schema}
+***************************************************************
+
+The errors in validation are as follows:
+
+"""
+
 
 # pylint: disable=too-many-instance-attributes
 # pylint: disable=too-many-arguments, too-many-locals
@@ -92,6 +116,7 @@ def __init__(
  external_scripts=None,
  external_stylesheets=None,
  suppress_callback_exceptions=None,
+ suppress_validation_exceptions=None,
  components_cache_max_age=None,
  **kwargs):
 
@@ -128,6 +153,10 @@ def __init__(
  'suppress_callback_exceptions',
  suppress_callback_exceptions, env_configs, False
  ),
+ 'suppress_validation_exceptions': _configs.get_config(
+ 'suppress_validation_exceptions',
+ suppress_validation_exceptions, env_configs, False
+ ),
  'routes_pathname_prefix': routes_pathname_prefix,
  'requests_pathname_prefix': requests_pathname_prefix,
  'include_assets_files': _configs.get_config(
@@ -765,7 +794,7 @@ def _validate_callback(self, output, inputs, state):
  output.component_id,
  output.component_property).replace(' ', ''))
 
- def _validate_callback_output(self, output_value, output):
+ def _debug_callback_serialization_error(self, output_value, output):
  valid = [str, dict, int, float, type(None), Component]
 
  def _raise_invalid(bad_val, outer_val, bad_type, path, index=None,
@@ -901,13 +930,11 @@ def callback(self, output, inputs=[], state=[]):
 
  def wrap_func(func):
  @wraps(func)
- def add_context(*args, **kwargs):
-
- output_value = func(*args, **kwargs)
+ def add_context(validated_output):
  response = {
  'response': {
  'props': {
- output.component_property: output_value
+ output.component_property: validated_output
  }
  }
  }
@@ -918,7 +945,10 @@ def add_context(*args, **kwargs):
  cls=plotly.utils.PlotlyJSONEncoder
  )
  except TypeError:
- self._validate_callback_output(output_value, output)
+ self._debug_callback_serialization_error(
+ validated_output,
+ output
+ )
  raise exceptions.InvalidCallbackReturnValue('''
  The callback for property `{property:s}`
  of component `{id:s}` returned a value
@@ -935,6 +965,7 @@ def add_context(*args, **kwargs):
  mimetype='application/json'
  )
 
+ self.callback_map[callback_id]['func'] = func
  self.callback_map[callback_id]['callback'] = add_context
 
  return add_context
@@ -978,7 +1009,62 @@ def dispatch(self):
  c['id'] == component_registration['id']
  ][0])
 
- return self.callback_map[target_id]['callback'](*args)
+ output_value = self.callback_map[target_id]['func'](*args)
+
+ # Only validate if we get required information from renderer
+ # and validation is not turned off by user
+ if not self.config.suppress_validation_exceptions and \
+ 'namespace' in output and 'type' in output:
+ # Python2.7 might make these keys and values unicode
+ namespace = str(output['namespace'])
+ component_type = str(output['type'])
+ component_id = str(output['id'])
+ component_property = str(output['property'])
+ callback_func_name = self.callback_map[target_id]['func'].__name__
+ self._validate_callback_output(namespace, component_type,
+ component_id, component_property,
+ callback_func_name,
+ args, output_value)
+
+ return self.callback_map[target_id]['callback'](output_value)
+
+ def _validate_callback_output(self, namespace, component_type,
+ component_id, component_property,
+ callback_func_name, args, value):
+ module = sys.modules[namespace]
+ component = getattr(module, component_type)
+ # pylint: disable=protected-access
+ validator = DashValidator({
+ component_property: component._schema.get(component_property, {})
+ })
+ valid = validator.validate({component_property: value})
+ if not valid:
+ error_message = _callback_validation_error_template.format(
+ component_property=component_property,
+ component_name=component.__name__,
+ component_id=component_id,
+ callback_func_name=callback_func_name,
+ args='({})'.format(", ".join(map(repr, args))),
+ value=value,
+ component_schema=pprint.pformat(
+ component._schema[component_property]
+ )
+ )
+
+ raise exceptions.CallbackOutputValidationError(
+ generate_validation_error_message(
+ validator.errors,
+ 0,
+ error_message
+ )
+ )
+ # Must also validate initialization of newly created components
+ if component_property == 'children':
+ if isinstance(value, Component):
+ value.validate()
+ for component in value.traverse():
+ if isinstance(component, Component):
+ component.validate()
 
  def _validate_layout(self):
  if self.layout is None:
@@ -995,6 +1081,11 @@ def _validate_layout(self):
 
  component_ids = {layout_id} if layout_id else set()
  for component in to_validate.traverse():
+ if (
+ not self.config.suppress_validation_exceptions and
+ isinstance(component, Component)
+ ):
+ component.validate()
  component_id = getattr(component, 'id', None)
  if component_id and component_id in component_ids:
  raise exceptions.DuplicateIdError(
@@ -1292,6 +1383,10 @@ def run_server(self,
  dev_tools_silence_routes_logging,
  )
 
+ if not debug:
+ # Do not throw validation exceptions in production.
+ self.config.suppress_validation_exceptions = True
+
  if self._dev_tools.silence_routes_logging:
  # Since it's silenced, the address don't show anymore.
  host = flask_run_options.get('host', '127.0.0.1')

dash/development/_py_components_generation.py

@@ -2,13 +2,16 @@
 import copy
 import os
 
-from dash.development.base_component import _explicitize_args
+from dash.development.base_component import (
+ _explicitize_args,
+ generate_property_schema
+)
 from dash.exceptions import NonExistentEventException
 from ._all_keywords import python_keywords
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(typename, props, description, namespace):
  """
  Dynamically generate class strings to have nicely formatted docstrings,
@@ -43,8 +46,12 @@ def generate_class_string(typename, props, description, namespace):
  # it to be `null` or whether that was just the default value.
  # The solution might be to deal with default values better although
  # not all component authors will supply those.
- c = '''class {typename}(Component):
+ c = '''\
+schema = {schema}
+
+class {typename}(Component):
  """{docstring}"""
+ _schema = schema
  @_explicitize_args
  def __init__(self, {default_argtext}):
  self._prop_names = {list_of_valid_keys}
@@ -55,7 +62,6 @@ def __init__(self, {default_argtext}):
  self.available_properties = {list_of_valid_keys}
  self.available_wildcard_properties =\
  {list_of_valid_wildcard_attr_prefixes}
-
  _explicit_args = kwargs.pop('_explicit_args')
  _locals = locals()
  _locals.update(kwargs) # For wildcard attrs
@@ -85,7 +91,7 @@ def __init__(self, {default_argtext}):
  default_argtext = "children=None, "
  argtext = 'children=children, **args'
  else:
- default_argtext = ""
+ default_argtext = ''
  argtext = '**args'
  default_argtext += ", ".join(
  [('{:s}=Component.REQUIRED'.format(p)
@@ -97,6 +103,10 @@ def __init__(self, {default_argtext}):
  p != 'setProps'] + ["**kwargs"]
  )
  required_args = required_props(props)
+ schema = {
+ k: generate_property_schema(v)
+ for k, v in props.items() if not k.endswith("-*")
+ }
  return c.format(
  typename=typename,
  namespace=namespace,
@@ -106,7 +116,8 @@ def __init__(self, {default_argtext}):
  docstring=docstring,
  default_argtext=default_argtext,
  argtext=argtext,
- required_props=required_args
+ required_props=required_args,
+ schema=schema
  )
 
 

.circleci/requirements/dev-requirements-py37.txt

@@ -14,3 +14,6 @@ requests[security]
 flake8
 pylint==2.2.2
 astroid==2.1.0
+Cerberus
+numpy
+pandas

.circleci/requirements/dev-requirements.txt

@@ -14,3 +14,6 @@ plotly==3.6.1
 requests[security]
 flake8
 pylint==1.9.4
+Cerberus
+numpy
+pandas

dash/_utils.py

@@ -84,3 +84,9 @@ def first(self, *names):
  value = self.get(name)
  if value:
  return value
+
+
+def _merge(x, y):
+ z = x.copy()
+ z.update(y)
+ return z

dash/dash.py

@@ -11,6 +11,7 @@
 import threading
 import warnings
 import re
+import pprint
 import logging
 
 from functools import wraps
@@ -25,6 +26,8 @@
 from .dependencies import Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component, ComponentRegistry
+from .development.validator import (DashValidator,
+ generate_validation_error_message)
 from . import exceptions
 from ._utils import AttributeDict as _AttributeDict
 from ._utils import interpolate_str as _interpolate
@@ -69,6 +72,27 @@
 _re_index_config_id = re.compile(r'id="_dash-config"')
 _re_index_scripts_id = re.compile(r'src=".*dash[-_]renderer.*"')
 
+_callback_validation_error_template = """
+A Dash Callback produced an invalid value!
+
+Dash tried to update the `{component_property}` prop of the
+`{component_name}` with id `{component_id}` by calling the
+`{callback_func_name}` function with `{args}` as arguments.
+
+This function call returned `{value}`, which did not pass
+validation tests for the `{component_name}` component.
+
+The expected schema for the `{component_property}` prop of the
+`{component_name}` component is:
+
+***************************************************************
+{component_schema}
+***************************************************************
+
+The errors in validation are as follows:
+
+"""
+
 
 # pylint: disable=too-many-instance-attributes
 # pylint: disable=too-many-arguments, too-many-locals
@@ -92,6 +116,7 @@ def __init__(
  external_scripts=None,
  external_stylesheets=None,
  suppress_callback_exceptions=None,
+ suppress_validation_exceptions=None,
  components_cache_max_age=None,
  **kwargs):
 
@@ -128,6 +153,10 @@ def __init__(
  'suppress_callback_exceptions',
  suppress_callback_exceptions, env_configs, False
  ),
+ 'suppress_validation_exceptions': _configs.get_config(
+ 'suppress_validation_exceptions',
+ suppress_validation_exceptions, env_configs, False
+ ),
  'routes_pathname_prefix': routes_pathname_prefix,
  'requests_pathname_prefix': requests_pathname_prefix,
  'include_assets_files': _configs.get_config(
@@ -765,7 +794,7 @@ def _validate_callback(self, output, inputs, state):
  output.component_id,
  output.component_property).replace(' ', ''))
 
- def _validate_callback_output(self, output_value, output):
+ def _debug_callback_serialization_error(self, output_value, output):
  valid = [str, dict, int, float, type(None), Component]
 
  def _raise_invalid(bad_val, outer_val, bad_type, path, index=None,
@@ -901,13 +930,11 @@ def callback(self, output, inputs=[], state=[]):
 
  def wrap_func(func):
  @wraps(func)
- def add_context(*args, **kwargs):
-
- output_value = func(*args, **kwargs)
+ def add_context(validated_output):
  response = {
  'response': {
  'props': {
- output.component_property: output_value
+ output.component_property: validated_output
  }
  }
  }
@@ -918,7 +945,10 @@ def add_context(*args, **kwargs):
  cls=plotly.utils.PlotlyJSONEncoder
  )
  except TypeError:
- self._validate_callback_output(output_value, output)
+ self._debug_callback_serialization_error(
+ validated_output,
+ output
+ )
  raise exceptions.InvalidCallbackReturnValue('''
  The callback for property `{property:s}`
  of component `{id:s}` returned a value
@@ -935,6 +965,7 @@ def add_context(*args, **kwargs):
  mimetype='application/json'
  )
 
+ self.callback_map[callback_id]['func'] = func
  self.callback_map[callback_id]['callback'] = add_context
 
  return add_context
@@ -978,7 +1009,62 @@ def dispatch(self):
  c['id'] == component_registration['id']
  ][0])
 
- return self.callback_map[target_id]['callback'](*args)
+ output_value = self.callback_map[target_id]['func'](*args)
+
+ # Only validate if we get required information from renderer
+ # and validation is not turned off by user
+ if not self.config.suppress_validation_exceptions and \
+ 'namespace' in output and 'type' in output:
+ # Python2.7 might make these keys and values unicode
+ namespace = str(output['namespace'])
+ component_type = str(output['type'])
+ component_id = str(output['id'])
+ component_property = str(output['property'])
+ callback_func_name = self.callback_map[target_id]['func'].__name__
+ self._validate_callback_output(namespace, component_type,
+ component_id, component_property,
+ callback_func_name,
+ args, output_value)
+
+ return self.callback_map[target_id]['callback'](output_value)
+
+ def _validate_callback_output(self, namespace, component_type,
+ component_id, component_property,
+ callback_func_name, args, value):
+ module = sys.modules[namespace]
+ component = getattr(module, component_type)
+ # pylint: disable=protected-access
+ validator = DashValidator({
+ component_property: component._schema.get(component_property, {})
+ })
+ valid = validator.validate({component_property: value})
+ if not valid:
+ error_message = _callback_validation_error_template.format(
+ component_property=component_property,
+ component_name=component.__name__,
+ component_id=component_id,
+ callback_func_name=callback_func_name,
+ args='({})'.format(", ".join(map(repr, args))),
+ value=value,
+ component_schema=pprint.pformat(
+ component._schema[component_property]
+ )
+ )
+
+ raise exceptions.CallbackOutputValidationError(
+ generate_validation_error_message(
+ validator.errors,
+ 0,
+ error_message
+ )
+ )
+ # Must also validate initialization of newly created components
+ if component_property == 'children':
+ if isinstance(value, Component):
+ value.validate()
+ for component in value.traverse():
+ if isinstance(component, Component):
+ component.validate()
 
  def _validate_layout(self):
  if self.layout is None:
@@ -995,6 +1081,11 @@ def _validate_layout(self):
 
  component_ids = {layout_id} if layout_id else set()
  for component in to_validate.traverse():
+ if (
+ not self.config.suppress_validation_exceptions and
+ isinstance(component, Component)
+ ):
+ component.validate()
  component_id = getattr(component, 'id', None)
  if component_id and component_id in component_ids:
  raise exceptions.DuplicateIdError(
@@ -1292,6 +1383,10 @@ def run_server(self,
  dev_tools_silence_routes_logging,
  )
 
+ if not debug:
+ # Do not throw validation exceptions in production.
+ self.config.suppress_validation_exceptions = True
+
  if self._dev_tools.silence_routes_logging:
  # Since it's silenced, the address don't show anymore.
  host = flask_run_options.get('host', '127.0.0.1')

dash/development/_py_components_generation.py

@@ -2,13 +2,16 @@
 import copy
 import os
 
-from dash.development.base_component import _explicitize_args
+from dash.development.base_component import (
+ _explicitize_args,
+ generate_property_schema
+)
 from dash.exceptions import NonExistentEventException
 from ._all_keywords import python_keywords
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(typename, props, description, namespace):
  """
  Dynamically generate class strings to have nicely formatted docstrings,
@@ -43,8 +46,12 @@ def generate_class_string(typename, props, description, namespace):
  # it to be `null` or whether that was just the default value.
  # The solution might be to deal with default values better although
  # not all component authors will supply those.
- c = '''class {typename}(Component):
+ c = '''\
+schema = {schema}
+
+class {typename}(Component):
  """{docstring}"""
+ _schema = schema
  @_explicitize_args
  def __init__(self, {default_argtext}):
  self._prop_names = {list_of_valid_keys}
@@ -55,7 +62,6 @@ def __init__(self, {default_argtext}):
  self.available_properties = {list_of_valid_keys}
  self.available_wildcard_properties =\
  {list_of_valid_wildcard_attr_prefixes}
-
  _explicit_args = kwargs.pop('_explicit_args')
  _locals = locals()
  _locals.update(kwargs) # For wildcard attrs
@@ -85,7 +91,7 @@ def __init__(self, {default_argtext}):
  default_argtext = "children=None, "
  argtext = 'children=children, **args'
  else:
- default_argtext = ""
+ default_argtext = ''
  argtext = '**args'
  default_argtext += ", ".join(
  [('{:s}=Component.REQUIRED'.format(p)
@@ -97,6 +103,10 @@ def __init__(self, {default_argtext}):
  p != 'setProps'] + ["**kwargs"]
  )
  required_args = required_props(props)
+ schema = {
+ k: generate_property_schema(v)
+ for k, v in props.items() if not k.endswith("-*")
+ }
  return c.format(
  typename=typename,
  namespace=namespace,
@@ -106,7 +116,8 @@ def __init__(self, {default_argtext}):
  docstring=docstring,
  default_argtext=default_argtext,
  argtext=argtext,
- required_props=required_args
+ required_props=required_args,
+ schema=schema
  )
 
 

.circleci/requirements/dev-requirements-py37.txt

@@ -14,3 +14,6 @@ requests[security]
 flake8
 pylint==2.2.2
 astroid==2.1.0
+Cerberus
+numpy
+pandas

.circleci/requirements/dev-requirements.txt

@@ -14,3 +14,6 @@ plotly==3.6.1
 requests[security]
 flake8
 pylint==1.9.4
+Cerberus
+numpy
+pandas

dash/_utils.py

@@ -84,3 +84,9 @@ def first(self, *names):
  value = self.get(name)
  if value:
  return value
+
+
+def _merge(x, y):
+ z = x.copy()
+ z.update(y)
+ return z

dash/dash.py

@@ -11,6 +11,7 @@
 import threading
 import warnings
 import re
+import pprint
 import logging
 
 from functools import wraps
@@ -25,6 +26,8 @@
 from .dependencies import Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component, ComponentRegistry
+from .development.validator import (DashValidator,
+ generate_validation_error_message)
 from . import exceptions
 from ._utils import AttributeDict as _AttributeDict
 from ._utils import interpolate_str as _interpolate
@@ -69,6 +72,27 @@
 _re_index_config_id = re.compile(r'id="_dash-config"')
 _re_index_scripts_id = re.compile(r'src=".*dash[-_]renderer.*"')
 
+_callback_validation_error_template = """
+A Dash Callback produced an invalid value!
+
+Dash tried to update the `{component_property}` prop of the
+`{component_name}` with id `{component_id}` by calling the
+`{callback_func_name}` function with `{args}` as arguments.
+
+This function call returned `{value}`, which did not pass
+validation tests for the `{component_name}` component.
+
+The expected schema for the `{component_property}` prop of the
+`{component_name}` component is:
+
+***************************************************************
+{component_schema}
+***************************************************************
+
+The errors in validation are as follows:
+
+"""
+
 
 # pylint: disable=too-many-instance-attributes
 # pylint: disable=too-many-arguments, too-many-locals
@@ -92,6 +116,7 @@ def __init__(
  external_scripts=None,
  external_stylesheets=None,
  suppress_callback_exceptions=None,
+ suppress_validation_exceptions=None,
  components_cache_max_age=None,
  **kwargs):
 
@@ -128,6 +153,10 @@ def __init__(
  'suppress_callback_exceptions',
  suppress_callback_exceptions, env_configs, False
  ),
+ 'suppress_validation_exceptions': _configs.get_config(
+ 'suppress_validation_exceptions',
+ suppress_validation_exceptions, env_configs, False
+ ),
  'routes_pathname_prefix': routes_pathname_prefix,
  'requests_pathname_prefix': requests_pathname_prefix,
  'include_assets_files': _configs.get_config(
@@ -765,7 +794,7 @@ def _validate_callback(self, output, inputs, state):
  output.component_id,
  output.component_property).replace(' ', ''))
 
- def _validate_callback_output(self, output_value, output):
+ def _debug_callback_serialization_error(self, output_value, output):
  valid = [str, dict, int, float, type(None), Component]
 
  def _raise_invalid(bad_val, outer_val, bad_type, path, index=None,
@@ -901,13 +930,11 @@ def callback(self, output, inputs=[], state=[]):
 
  def wrap_func(func):
  @wraps(func)
- def add_context(*args, **kwargs):
-
- output_value = func(*args, **kwargs)
+ def add_context(validated_output):
  response = {
  'response': {
  'props': {
- output.component_property: output_value
+ output.component_property: validated_output
  }
  }
  }
@@ -918,7 +945,10 @@ def add_context(*args, **kwargs):
  cls=plotly.utils.PlotlyJSONEncoder
  )
  except TypeError:
- self._validate_callback_output(output_value, output)
+ self._debug_callback_serialization_error(
+ validated_output,
+ output
+ )
  raise exceptions.InvalidCallbackReturnValue('''
  The callback for property `{property:s}`
  of component `{id:s}` returned a value
@@ -935,6 +965,7 @@ def add_context(*args, **kwargs):
  mimetype='application/json'
  )
 
+ self.callback_map[callback_id]['func'] = func
  self.callback_map[callback_id]['callback'] = add_context
 
  return add_context
@@ -978,7 +1009,62 @@ def dispatch(self):
  c['id'] == component_registration['id']
  ][0])
 
- return self.callback_map[target_id]['callback'](*args)
+ output_value = self.callback_map[target_id]['func'](*args)
+
+ # Only validate if we get required information from renderer
+ # and validation is not turned off by user
+ if not self.config.suppress_validation_exceptions and \
+ 'namespace' in output and 'type' in output:
+ # Python2.7 might make these keys and values unicode
+ namespace = str(output['namespace'])
+ component_type = str(output['type'])
+ component_id = str(output['id'])
+ component_property = str(output['property'])
+ callback_func_name = self.callback_map[target_id]['func'].__name__
+ self._validate_callback_output(namespace, component_type,
+ component_id, component_property,
+ callback_func_name,
+ args, output_value)
+
+ return self.callback_map[target_id]['callback'](output_value)
+
+ def _validate_callback_output(self, namespace, component_type,
+ component_id, component_property,
+ callback_func_name, args, value):
+ module = sys.modules[namespace]
+ component = getattr(module, component_type)
+ # pylint: disable=protected-access
+ validator = DashValidator({
+ component_property: component._schema.get(component_property, {})
+ })
+ valid = validator.validate({component_property: value})
+ if not valid:
+ error_message = _callback_validation_error_template.format(
+ component_property=component_property,
+ component_name=component.__name__,
+ component_id=component_id,
+ callback_func_name=callback_func_name,
+ args='({})'.format(", ".join(map(repr, args))),
+ value=value,
+ component_schema=pprint.pformat(
+ component._schema[component_property]
+ )
+ )
+
+ raise exceptions.CallbackOutputValidationError(
+ generate_validation_error_message(
+ validator.errors,
+ 0,
+ error_message
+ )
+ )
+ # Must also validate initialization of newly created components
+ if component_property == 'children':
+ if isinstance(value, Component):
+ value.validate()
+ for component in value.traverse():
+ if isinstance(component, Component):
+ component.validate()
 
  def _validate_layout(self):
  if self.layout is None:
@@ -995,6 +1081,11 @@ def _validate_layout(self):
 
  component_ids = {layout_id} if layout_id else set()
  for component in to_validate.traverse():
+ if (
+ not self.config.suppress_validation_exceptions and
+ isinstance(component, Component)
+ ):
+ component.validate()
  component_id = getattr(component, 'id', None)
  if component_id and component_id in component_ids:
  raise exceptions.DuplicateIdError(
@@ -1292,6 +1383,10 @@ def run_server(self,
  dev_tools_silence_routes_logging,
  )
 
+ if not debug:
+ # Do not throw validation exceptions in production.
+ self.config.suppress_validation_exceptions = True
+
  if self._dev_tools.silence_routes_logging:
  # Since it's silenced, the address don't show anymore.
  host = flask_run_options.get('host', '127.0.0.1')

dash/development/_py_components_generation.py

@@ -2,13 +2,16 @@
 import copy
 import os
 
-from dash.development.base_component import _explicitize_args
+from dash.development.base_component import (
+ _explicitize_args,
+ generate_property_schema
+)
 from dash.exceptions import NonExistentEventException
 from ._all_keywords import python_keywords
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(typename, props, description, namespace):
  """
  Dynamically generate class strings to have nicely formatted docstrings,
@@ -43,8 +46,12 @@ def generate_class_string(typename, props, description, namespace):
  # it to be `null` or whether that was just the default value.
  # The solution might be to deal with default values better although
  # not all component authors will supply those.
- c = '''class {typename}(Component):
+ c = '''\
+schema = {schema}
+
+class {typename}(Component):
  """{docstring}"""
+ _schema = schema
  @_explicitize_args
  def __init__(self, {default_argtext}):
  self._prop_names = {list_of_valid_keys}
@@ -55,7 +62,6 @@ def __init__(self, {default_argtext}):
  self.available_properties = {list_of_valid_keys}
  self.available_wildcard_properties =\
  {list_of_valid_wildcard_attr_prefixes}
-
  _explicit_args = kwargs.pop('_explicit_args')
  _locals = locals()
  _locals.update(kwargs) # For wildcard attrs
@@ -85,7 +91,7 @@ def __init__(self, {default_argtext}):
  default_argtext = "children=None, "
  argtext = 'children=children, **args'
  else:
- default_argtext = ""
+ default_argtext = ''
  argtext = '**args'
  default_argtext += ", ".join(
  [('{:s}=Component.REQUIRED'.format(p)
@@ -97,6 +103,10 @@ def __init__(self, {default_argtext}):
  p != 'setProps'] + ["**kwargs"]
  )
  required_args = required_props(props)
+ schema = {
+ k: generate_property_schema(v)
+ for k, v in props.items() if not k.endswith("-*")
+ }
  return c.format(
  typename=typename,
  namespace=namespace,
@@ -106,7 +116,8 @@ def __init__(self, {default_argtext}):
  docstring=docstring,
  default_argtext=default_argtext,
  argtext=argtext,
- required_props=required_args
+ required_props=required_args,
+ schema=schema
  )
 
 

.circleci/requirements/dev-requirements-py37.txt

@@ -14,3 +14,6 @@ requests[security]
 flake8
 pylint==2.2.2
 astroid==2.1.0
+Cerberus
+numpy
+pandas

.circleci/requirements/dev-requirements.txt

@@ -14,3 +14,6 @@ plotly==3.6.1
 requests[security]
 flake8
 pylint==1.9.4
+Cerberus
+numpy
+pandas

dash/_utils.py

@@ -84,3 +84,9 @@ def first(self, *names):
  value = self.get(name)
  if value:
  return value
+
+
+def _merge(x, y):
+ z = x.copy()
+ z.update(y)
+ return z

dash/dash.py

@@ -11,6 +11,7 @@
 import threading
 import warnings
 import re
+import pprint
 import logging
 
 from functools import wraps
@@ -25,6 +26,8 @@
 from .dependencies import Input, Output, State
 from .resources import Scripts, Css
 from .development.base_component import Component, ComponentRegistry
+from .development.validator import (DashValidator,
+ generate_validation_error_message)
 from . import exceptions
 from ._utils import AttributeDict as _AttributeDict
 from ._utils import interpolate_str as _interpolate
@@ -69,6 +72,27 @@
 _re_index_config_id = re.compile(r'id="_dash-config"')
 _re_index_scripts_id = re.compile(r'src=".*dash[-_]renderer.*"')
 
+_callback_validation_error_template = """
+A Dash Callback produced an invalid value!
+
+Dash tried to update the `{component_property}` prop of the
+`{component_name}` with id `{component_id}` by calling the
+`{callback_func_name}` function with `{args}` as arguments.
+
+This function call returned `{value}`, which did not pass
+validation tests for the `{component_name}` component.
+
+The expected schema for the `{component_property}` prop of the
+`{component_name}` component is:
+
+***************************************************************
+{component_schema}
+***************************************************************
+
+The errors in validation are as follows:
+
+"""
+
 
 # pylint: disable=too-many-instance-attributes
 # pylint: disable=too-many-arguments, too-many-locals
@@ -92,6 +116,7 @@ def __init__(
  external_scripts=None,
  external_stylesheets=None,
  suppress_callback_exceptions=None,
+ suppress_validation_exceptions=None,
  components_cache_max_age=None,
  **kwargs):
 
@@ -128,6 +153,10 @@ def __init__(
  'suppress_callback_exceptions',
  suppress_callback_exceptions, env_configs, False
  ),
+ 'suppress_validation_exceptions': _configs.get_config(
+ 'suppress_validation_exceptions',
+ suppress_validation_exceptions, env_configs, False
+ ),
  'routes_pathname_prefix': routes_pathname_prefix,
  'requests_pathname_prefix': requests_pathname_prefix,
  'include_assets_files': _configs.get_config(
@@ -765,7 +794,7 @@ def _validate_callback(self, output, inputs, state):
  output.component_id,
  output.component_property).replace(' ', ''))
 
- def _validate_callback_output(self, output_value, output):
+ def _debug_callback_serialization_error(self, output_value, output):
  valid = [str, dict, int, float, type(None), Component]
 
  def _raise_invalid(bad_val, outer_val, bad_type, path, index=None,
@@ -901,13 +930,11 @@ def callback(self, output, inputs=[], state=[]):
 
  def wrap_func(func):
  @wraps(func)
- def add_context(*args, **kwargs):
-
- output_value = func(*args, **kwargs)
+ def add_context(validated_output):
  response = {
  'response': {
  'props': {
- output.component_property: output_value
+ output.component_property: validated_output
  }
  }
  }
@@ -918,7 +945,10 @@ def add_context(*args, **kwargs):
  cls=plotly.utils.PlotlyJSONEncoder
  )
  except TypeError:
- self._validate_callback_output(output_value, output)
+ self._debug_callback_serialization_error(
+ validated_output,
+ output
+ )
  raise exceptions.InvalidCallbackReturnValue('''
  The callback for property `{property:s}`
  of component `{id:s}` returned a value
@@ -935,6 +965,7 @@ def add_context(*args, **kwargs):
  mimetype='application/json'
  )
 
+ self.callback_map[callback_id]['func'] = func
  self.callback_map[callback_id]['callback'] = add_context
 
  return add_context
@@ -978,7 +1009,62 @@ def dispatch(self):
  c['id'] == component_registration['id']
  ][0])
 
- return self.callback_map[target_id]['callback'](*args)
+ output_value = self.callback_map[target_id]['func'](*args)
+
+ # Only validate if we get required information from renderer
+ # and validation is not turned off by user
+ if not self.config.suppress_validation_exceptions and \
+ 'namespace' in output and 'type' in output:
+ # Python2.7 might make these keys and values unicode
+ namespace = str(output['namespace'])
+ component_type = str(output['type'])
+ component_id = str(output['id'])
+ component_property = str(output['property'])
+ callback_func_name = self.callback_map[target_id]['func'].__name__
+ self._validate_callback_output(namespace, component_type,
+ component_id, component_property,
+ callback_func_name,
+ args, output_value)
+
+ return self.callback_map[target_id]['callback'](output_value)
+
+ def _validate_callback_output(self, namespace, component_type,
+ component_id, component_property,
+ callback_func_name, args, value):
+ module = sys.modules[namespace]
+ component = getattr(module, component_type)
+ # pylint: disable=protected-access
+ validator = DashValidator({
+ component_property: component._schema.get(component_property, {})
+ })
+ valid = validator.validate({component_property: value})
+ if not valid:
+ error_message = _callback_validation_error_template.format(
+ component_property=component_property,
+ component_name=component.__name__,
+ component_id=component_id,
+ callback_func_name=callback_func_name,
+ args='({})'.format(", ".join(map(repr, args))),
+ value=value,
+ component_schema=pprint.pformat(
+ component._schema[component_property]
+ )
+ )
+
+ raise exceptions.CallbackOutputValidationError(
+ generate_validation_error_message(
+ validator.errors,
+ 0,
+ error_message
+ )
+ )
+ # Must also validate initialization of newly created components
+ if component_property == 'children':
+ if isinstance(value, Component):
+ value.validate()
+ for component in value.traverse():
+ if isinstance(component, Component):
+ component.validate()
 
  def _validate_layout(self):
  if self.layout is None:
@@ -995,6 +1081,11 @@ def _validate_layout(self):
 
  component_ids = {layout_id} if layout_id else set()
  for component in to_validate.traverse():
+ if (
+ not self.config.suppress_validation_exceptions and
+ isinstance(component, Component)
+ ):
+ component.validate()
  component_id = getattr(component, 'id', None)
  if component_id and component_id in component_ids:
  raise exceptions.DuplicateIdError(
@@ -1292,6 +1383,10 @@ def run_server(self,
  dev_tools_silence_routes_logging,
  )
 
+ if not debug:
+ # Do not throw validation exceptions in production.
+ self.config.suppress_validation_exceptions = True
+
  if self._dev_tools.silence_routes_logging:
  # Since it's silenced, the address don't show anymore.
  host = flask_run_options.get('host', '127.0.0.1')

dash/development/_py_components_generation.py

@@ -2,13 +2,16 @@
 import copy
 import os
 
-from dash.development.base_component import _explicitize_args
+from dash.development.base_component import (
+ _explicitize_args,
+ generate_property_schema
+)
 from dash.exceptions import NonExistentEventException
 from ._all_keywords import python_keywords
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(typename, props, description, namespace):
  """
  Dynamically generate class strings to have nicely formatted docstrings,
@@ -43,8 +46,12 @@ def generate_class_string(typename, props, description, namespace):
  # it to be `null` or whether that was just the default value.
  # The solution might be to deal with default values better although
  # not all component authors will supply those.
- c = '''class {typename}(Component):
+ c = '''\
+schema = {schema}
+
+class {typename}(Component):
  """{docstring}"""
+ _schema = schema
  @_explicitize_args
  def __init__(self, {default_argtext}):
  self._prop_names = {list_of_valid_keys}
@@ -55,7 +62,6 @@ def __init__(self, {default_argtext}):
  self.available_properties = {list_of_valid_keys}
  self.available_wildcard_properties =\
  {list_of_valid_wildcard_attr_prefixes}
-
  _explicit_args = kwargs.pop('_explicit_args')
  _locals = locals()
  _locals.update(kwargs) # For wildcard attrs
@@ -85,7 +91,7 @@ def __init__(self, {default_argtext}):
  default_argtext = "children=None, "
  argtext = 'children=children, **args'
  else:
- default_argtext = ""
+ default_argtext = ''
  argtext = '**args'
  default_argtext += ", ".join(
  [('{:s}=Component.REQUIRED'.format(p)
@@ -97,6 +103,10 @@ def __init__(self, {default_argtext}):
  p != 'setProps'] + ["**kwargs"]
  )
  required_args = required_props(props)
+ schema = {
+ k: generate_property_schema(v)
+ for k, v in props.items() if not k.endswith("-*")
+ }
  return c.format(
  typename=typename,
  namespace=namespace,
@@ -106,7 +116,8 @@ def __init__(self, {default_argtext}):
  docstring=docstring,
  default_argtext=default_argtext,
  argtext=argtext,
- required_props=required_args
+ required_props=required_args,
+ schema=schema
  )