get_relative_path, strip_relative_path, get_asset_url

.circleci/config.yml

@@ -111,7 +111,7 @@ jobs:
  . venv/bin/activate
  set -eo pipefail
  pip install -e . --progress-bar off && pip list | grep dash
- npm install --production && npm run initialize
+ npm install npm run initialize
  npm run build
  npm run lint
  - run:

CHANGELOG.md

@@ -4,6 +4,16 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added 
+- [#1923](https://github.com/plotly/dash/pull/1923):
+- `dash.get_relative_path`
+- `dash.strip_relative_path`
+- `dash.get_asset_url`
+This is similar to `dash.callback` where you don't need the `app` object. It makes it possible to use these
+functions in the `pages` folder of a multi-page app without running into the circular `app` imports issue.
+
+## [2.1.0] - 2022-01-22
+
 ### Changed
 - [#1876](https://github.com/plotly/dash/pull/1876) Delays finalizing `Dash.config` attributes not used in the constructor until `init_app()`.
 - [#1869](https://github.com/plotly/dash/pull/1869), [#1873](https://github.com/plotly/dash/pull/1873) Upgrade Plotly.js to v2.8.3. This includes:

dash/__init__.py

@@ -21,3 +21,8 @@
 from .version import __version__ # noqa: F401,E402
 from ._callback_context import callback_context # noqa: F401,E402
 from ._callback import callback, clientside_callback # noqa: F401,E402
+from ._get_paths import ( # noqa: F401,E402
+ get_asset_url,
+ get_relative_path,
+ strip_relative_path,
+)

dash/_get_paths.py

@@ -0,0 +1,155 @@
+from ._utils import AttributeDict
+from . import exceptions
+
+CONFIG = AttributeDict()
+
+
+def get_asset_url(path):
+ return app_get_asset_url(CONFIG, path)
+
+
+def app_get_asset_url(config, path):
+ if config.assets_external_path:
+ prefix = config.assets_external_path
+ else:
+ prefix = config.requests_pathname_prefix
+ return "/".join(
+ [
+ # Only take the first part of the pathname
+ prefix.rstrip("/"),
+ config.assets_url_path.lstrip("/"),
+ path,
+ ]
+ )
+
+
+def get_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` prefixed before it.
+ Use this function when specifying local URL paths that will work
+ in environments regardless of what `requests_pathname_prefix` is.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name,
+ e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`.
+ This can be used as an alternative to `get_asset_url` as well with
+ `app.get_relative_path('/assets/logo.png')`
+
+ Use this function with `app.strip_relative_path` in callbacks that
+ deal with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ """
+ return app_get_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_get_relative_path(requests_pathname, path):
+ if requests_pathname == "/" and path == "":
+ return "/"
+ if requests_pathname != "/" and path == "":
+ return requests_pathname
+ if not path.startswith("/"):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with a leading / are not supported.
+ You supplied: {}
+ """.format(
+ path
+ )
+ )
+ return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
+
+
+def strip_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` and leading and trailing
+ slashes stripped from it. Also, if None is passed in, None is returned.
+ Use this function with `get_relative_path` in callbacks that deal
+ with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ Note that `chapters.page_1` will be served if the user visits `/page-1`
+ _or_ `/page-1/` since `strip_relative_path` removes the trailing slash.
+
+ Also note that `strip_relative_path` is compatible with
+ `get_relative_path` in environments where `requests_pathname_prefix` set.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name, e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`
+
+ The `pathname` property of `dcc.Location` will return '`/my-dash-app/page-2`'
+ to the callback.
+ In this case, `app.strip_relative_path('/my-dash-app/page-2')`
+ will return `'page-2'`
+
+ For nested URLs, slashes are still included:
+ `app.strip_relative_path('/page-1/sub-page-1/')` will return
+ `page-1/sub-page-1`
+ ```
+ """
+ return app_strip_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_strip_relative_path(requests_pathname, path):
+ if path is None:
+ return None
+ if (
+ requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
+ ) or (requests_pathname == "/" and not path.startswith("/")):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with requests_pathname_prefix are not supported.
+ You supplied: {} and requests_pathname_prefix was {}
+ """.format(
+ path, requests_pathname
+ )
+ )
+ if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
+ path = path.replace(
+ # handle the case where the path might be `/my-dash-app`
+ # but the requests_pathname_prefix is `/my-dash-app/`
+ requests_pathname.rstrip("/"),
+ "",
+ 1,
+ )
+ return path.strip("/")

dash/_utils.py

@@ -9,7 +9,6 @@
 import io
 import json
 from functools import wraps
-from . import exceptions
 
 logger = logging.getLogger()
 
@@ -47,60 +46,6 @@ def generate_hash():
  return str(uuid.uuid4().hex).strip("-")
 
 
-def get_asset_path(requests_pathname, asset_path, asset_url_path):
-
- return "/".join(
- [
- # Only take the first part of the pathname
- requests_pathname.rstrip("/"),
- asset_url_path,
- asset_path,
- ]
- )
-
-
-def get_relative_path(requests_pathname, path):
- if requests_pathname == "/" and path == "":
- return "/"
- if requests_pathname != "/" and path == "":
- return requests_pathname
- if not path.startswith("/"):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with a leading / are not supported.
- You supplied: {}
- """.format(
- path
- )
- )
- return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
-
-
-def strip_relative_path(requests_pathname, path):
- if path is None:
- return None
- if (
- requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
- ) or (requests_pathname == "/" and not path.startswith("/")):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with requests_pathname_prefix are not supported.
- You supplied: {} and requests_pathname_prefix was {}
- """.format(
- path, requests_pathname
- )
- )
- if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
- path = path.replace(
- # handle the case where the path might be `/my-dash-app`
- # but the requests_pathname_prefix is `/my-dash-app/`
- requests_pathname.rstrip("/"),
- "",
- 1,
- )
- return path.strip("/")
-
-
 # pylint: disable=no-member
 def patch_collections_abc(member):
  return getattr(collections.abc, member)

dash/dash.py

@@ -42,17 +42,15 @@
  AttributeDict,
  format_tag,
  generate_hash,
- get_asset_path,
- get_relative_path,
  inputs_to_dict,
  inputs_to_vals,
  interpolate_str,
  patch_collections_abc,
  split_callback_id,
- strip_relative_path,
  to_json,
 )
 from . import _callback
+from . import _get_paths
 from . import _dash_renderer
 from . import _validate
 from . import _watch
@@ -366,6 +364,8 @@ def __init__(
  "via the Dash constructor"
  )
 
+ _get_paths.CONFIG = self.config
+
  # keep title as a class property for backwards compatibility
  self.title = title
 
@@ -1470,14 +1470,7 @@ def csp_hashes(self, hash_algorithm="sha256"):
  ]
 
  def get_asset_url(self, path):
- if self.config.assets_external_path:
- prefix = self.config.assets_external_path
- else:
- prefix = self.config.requests_pathname_prefix
-
- asset = get_asset_path(prefix, path, self.config.assets_url_path.lstrip("/"))
-
- return asset
+ return _get_paths.app_get_asset_url(self.config, path)
 
  def get_relative_path(self, path):
  """
@@ -1516,9 +1509,9 @@ def display_content(path):
  return chapters.page_2
  ```
  """
-asset = get_relative_path(self.config.requests_pathname_prefix, path)
-
-return asset
+return _get_paths.app_get_relative_path(
+ self.config.requests_pathname_prefix, path
+)
 
  def strip_relative_path(self, path):
  """
@@ -1567,7 +1560,9 @@ def display_content(path):
  `page-1/sub-page-1`
  ```
  """
- return strip_relative_path(self.config.requests_pathname_prefix, path)
+ return _get_paths.app_strip_relative_path(
+ self.config.requests_pathname_prefix, path
+ )
 
  def _setup_dev_tools(self, **kwargs):
  debug = kwargs.get("debug", False)

.circleci/config.yml

@@ -111,7 +111,7 @@ jobs:
  . venv/bin/activate
  set -eo pipefail
  pip install -e . --progress-bar off && pip list | grep dash
- npm install --production && npm run initialize
+ npm install npm run initialize
  npm run build
  npm run lint
  - run:

CHANGELOG.md

@@ -4,6 +4,16 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added 
+- [#1923](https://github.com/plotly/dash/pull/1923):
+- `dash.get_relative_path`
+- `dash.strip_relative_path`
+- `dash.get_asset_url`
+This is similar to `dash.callback` where you don't need the `app` object. It makes it possible to use these
+functions in the `pages` folder of a multi-page app without running into the circular `app` imports issue.
+
+## [2.1.0] - 2022-01-22
+
 ### Changed
 - [#1876](https://github.com/plotly/dash/pull/1876) Delays finalizing `Dash.config` attributes not used in the constructor until `init_app()`.
 - [#1869](https://github.com/plotly/dash/pull/1869), [#1873](https://github.com/plotly/dash/pull/1873) Upgrade Plotly.js to v2.8.3. This includes:

dash/__init__.py

@@ -21,3 +21,8 @@
 from .version import __version__ # noqa: F401,E402
 from ._callback_context import callback_context # noqa: F401,E402
 from ._callback import callback, clientside_callback # noqa: F401,E402
+from ._get_paths import ( # noqa: F401,E402
+ get_asset_url,
+ get_relative_path,
+ strip_relative_path,
+)

dash/_get_paths.py

@@ -0,0 +1,155 @@
+from ._utils import AttributeDict
+from . import exceptions
+
+CONFIG = AttributeDict()
+
+
+def get_asset_url(path):
+ return app_get_asset_url(CONFIG, path)
+
+
+def app_get_asset_url(config, path):
+ if config.assets_external_path:
+ prefix = config.assets_external_path
+ else:
+ prefix = config.requests_pathname_prefix
+ return "/".join(
+ [
+ # Only take the first part of the pathname
+ prefix.rstrip("/"),
+ config.assets_url_path.lstrip("/"),
+ path,
+ ]
+ )
+
+
+def get_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` prefixed before it.
+ Use this function when specifying local URL paths that will work
+ in environments regardless of what `requests_pathname_prefix` is.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name,
+ e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`.
+ This can be used as an alternative to `get_asset_url` as well with
+ `app.get_relative_path('/assets/logo.png')`
+
+ Use this function with `app.strip_relative_path` in callbacks that
+ deal with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ """
+ return app_get_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_get_relative_path(requests_pathname, path):
+ if requests_pathname == "/" and path == "":
+ return "/"
+ if requests_pathname != "/" and path == "":
+ return requests_pathname
+ if not path.startswith("/"):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with a leading / are not supported.
+ You supplied: {}
+ """.format(
+ path
+ )
+ )
+ return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
+
+
+def strip_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` and leading and trailing
+ slashes stripped from it. Also, if None is passed in, None is returned.
+ Use this function with `get_relative_path` in callbacks that deal
+ with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ Note that `chapters.page_1` will be served if the user visits `/page-1`
+ _or_ `/page-1/` since `strip_relative_path` removes the trailing slash.
+
+ Also note that `strip_relative_path` is compatible with
+ `get_relative_path` in environments where `requests_pathname_prefix` set.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name, e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`
+
+ The `pathname` property of `dcc.Location` will return '`/my-dash-app/page-2`'
+ to the callback.
+ In this case, `app.strip_relative_path('/my-dash-app/page-2')`
+ will return `'page-2'`
+
+ For nested URLs, slashes are still included:
+ `app.strip_relative_path('/page-1/sub-page-1/')` will return
+ `page-1/sub-page-1`
+ ```
+ """
+ return app_strip_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_strip_relative_path(requests_pathname, path):
+ if path is None:
+ return None
+ if (
+ requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
+ ) or (requests_pathname == "/" and not path.startswith("/")):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with requests_pathname_prefix are not supported.
+ You supplied: {} and requests_pathname_prefix was {}
+ """.format(
+ path, requests_pathname
+ )
+ )
+ if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
+ path = path.replace(
+ # handle the case where the path might be `/my-dash-app`
+ # but the requests_pathname_prefix is `/my-dash-app/`
+ requests_pathname.rstrip("/"),
+ "",
+ 1,
+ )
+ return path.strip("/")

dash/_utils.py

@@ -9,7 +9,6 @@
 import io
 import json
 from functools import wraps
-from . import exceptions
 
 logger = logging.getLogger()
 
@@ -47,60 +46,6 @@ def generate_hash():
  return str(uuid.uuid4().hex).strip("-")
 
 
-def get_asset_path(requests_pathname, asset_path, asset_url_path):
-
- return "/".join(
- [
- # Only take the first part of the pathname
- requests_pathname.rstrip("/"),
- asset_url_path,
- asset_path,
- ]
- )
-
-
-def get_relative_path(requests_pathname, path):
- if requests_pathname == "/" and path == "":
- return "/"
- if requests_pathname != "/" and path == "":
- return requests_pathname
- if not path.startswith("/"):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with a leading / are not supported.
- You supplied: {}
- """.format(
- path
- )
- )
- return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
-
-
-def strip_relative_path(requests_pathname, path):
- if path is None:
- return None
- if (
- requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
- ) or (requests_pathname == "/" and not path.startswith("/")):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with requests_pathname_prefix are not supported.
- You supplied: {} and requests_pathname_prefix was {}
- """.format(
- path, requests_pathname
- )
- )
- if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
- path = path.replace(
- # handle the case where the path might be `/my-dash-app`
- # but the requests_pathname_prefix is `/my-dash-app/`
- requests_pathname.rstrip("/"),
- "",
- 1,
- )
- return path.strip("/")
-
-
 # pylint: disable=no-member
 def patch_collections_abc(member):
  return getattr(collections.abc, member)

dash/dash.py

@@ -42,17 +42,15 @@
  AttributeDict,
  format_tag,
  generate_hash,
- get_asset_path,
- get_relative_path,
  inputs_to_dict,
  inputs_to_vals,
  interpolate_str,
  patch_collections_abc,
  split_callback_id,
- strip_relative_path,
  to_json,
 )
 from . import _callback
+from . import _get_paths
 from . import _dash_renderer
 from . import _validate
 from . import _watch
@@ -366,6 +364,8 @@ def __init__(
  "via the Dash constructor"
  )
 
+ _get_paths.CONFIG = self.config
+
  # keep title as a class property for backwards compatibility
  self.title = title
 
@@ -1470,14 +1470,7 @@ def csp_hashes(self, hash_algorithm="sha256"):
  ]
 
  def get_asset_url(self, path):
- if self.config.assets_external_path:
- prefix = self.config.assets_external_path
- else:
- prefix = self.config.requests_pathname_prefix
-
- asset = get_asset_path(prefix, path, self.config.assets_url_path.lstrip("/"))
-
- return asset
+ return _get_paths.app_get_asset_url(self.config, path)
 
  def get_relative_path(self, path):
  """
@@ -1516,9 +1509,9 @@ def display_content(path):
  return chapters.page_2
  ```
  """
-asset = get_relative_path(self.config.requests_pathname_prefix, path)
-
-return asset
+return _get_paths.app_get_relative_path(
+ self.config.requests_pathname_prefix, path
+)
 
  def strip_relative_path(self, path):
  """
@@ -1567,7 +1560,9 @@ def display_content(path):
  `page-1/sub-page-1`
  ```
  """
- return strip_relative_path(self.config.requests_pathname_prefix, path)
+ return _get_paths.app_strip_relative_path(
+ self.config.requests_pathname_prefix, path
+ )
 
  def _setup_dev_tools(self, **kwargs):
  debug = kwargs.get("debug", False)

.circleci/config.yml

@@ -111,7 +111,7 @@ jobs:
  . venv/bin/activate
  set -eo pipefail
  pip install -e . --progress-bar off && pip list | grep dash
- npm install --production && npm run initialize
+ npm install npm run initialize
  npm run build
  npm run lint
  - run:

CHANGELOG.md

@@ -4,6 +4,16 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added 
+- [#1923](https://github.com/plotly/dash/pull/1923):
+- `dash.get_relative_path`
+- `dash.strip_relative_path`
+- `dash.get_asset_url`
+This is similar to `dash.callback` where you don't need the `app` object. It makes it possible to use these
+functions in the `pages` folder of a multi-page app without running into the circular `app` imports issue.
+
+## [2.1.0] - 2022-01-22
+
 ### Changed
 - [#1876](https://github.com/plotly/dash/pull/1876) Delays finalizing `Dash.config` attributes not used in the constructor until `init_app()`.
 - [#1869](https://github.com/plotly/dash/pull/1869), [#1873](https://github.com/plotly/dash/pull/1873) Upgrade Plotly.js to v2.8.3. This includes:

dash/__init__.py

@@ -21,3 +21,8 @@
 from .version import __version__ # noqa: F401,E402
 from ._callback_context import callback_context # noqa: F401,E402
 from ._callback import callback, clientside_callback # noqa: F401,E402
+from ._get_paths import ( # noqa: F401,E402
+ get_asset_url,
+ get_relative_path,
+ strip_relative_path,
+)

dash/_get_paths.py

@@ -0,0 +1,155 @@
+from ._utils import AttributeDict
+from . import exceptions
+
+CONFIG = AttributeDict()
+
+
+def get_asset_url(path):
+ return app_get_asset_url(CONFIG, path)
+
+
+def app_get_asset_url(config, path):
+ if config.assets_external_path:
+ prefix = config.assets_external_path
+ else:
+ prefix = config.requests_pathname_prefix
+ return "/".join(
+ [
+ # Only take the first part of the pathname
+ prefix.rstrip("/"),
+ config.assets_url_path.lstrip("/"),
+ path,
+ ]
+ )
+
+
+def get_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` prefixed before it.
+ Use this function when specifying local URL paths that will work
+ in environments regardless of what `requests_pathname_prefix` is.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name,
+ e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`.
+ This can be used as an alternative to `get_asset_url` as well with
+ `app.get_relative_path('/assets/logo.png')`
+
+ Use this function with `app.strip_relative_path` in callbacks that
+ deal with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ """
+ return app_get_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_get_relative_path(requests_pathname, path):
+ if requests_pathname == "/" and path == "":
+ return "/"
+ if requests_pathname != "/" and path == "":
+ return requests_pathname
+ if not path.startswith("/"):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with a leading / are not supported.
+ You supplied: {}
+ """.format(
+ path
+ )
+ )
+ return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
+
+
+def strip_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` and leading and trailing
+ slashes stripped from it. Also, if None is passed in, None is returned.
+ Use this function with `get_relative_path` in callbacks that deal
+ with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ Note that `chapters.page_1` will be served if the user visits `/page-1`
+ _or_ `/page-1/` since `strip_relative_path` removes the trailing slash.
+
+ Also note that `strip_relative_path` is compatible with
+ `get_relative_path` in environments where `requests_pathname_prefix` set.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name, e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`
+
+ The `pathname` property of `dcc.Location` will return '`/my-dash-app/page-2`'
+ to the callback.
+ In this case, `app.strip_relative_path('/my-dash-app/page-2')`
+ will return `'page-2'`
+
+ For nested URLs, slashes are still included:
+ `app.strip_relative_path('/page-1/sub-page-1/')` will return
+ `page-1/sub-page-1`
+ ```
+ """
+ return app_strip_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_strip_relative_path(requests_pathname, path):
+ if path is None:
+ return None
+ if (
+ requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
+ ) or (requests_pathname == "/" and not path.startswith("/")):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with requests_pathname_prefix are not supported.
+ You supplied: {} and requests_pathname_prefix was {}
+ """.format(
+ path, requests_pathname
+ )
+ )
+ if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
+ path = path.replace(
+ # handle the case where the path might be `/my-dash-app`
+ # but the requests_pathname_prefix is `/my-dash-app/`
+ requests_pathname.rstrip("/"),
+ "",
+ 1,
+ )
+ return path.strip("/")

dash/_utils.py

@@ -9,7 +9,6 @@
 import io
 import json
 from functools import wraps
-from . import exceptions
 
 logger = logging.getLogger()
 
@@ -47,60 +46,6 @@ def generate_hash():
  return str(uuid.uuid4().hex).strip("-")
 
 
-def get_asset_path(requests_pathname, asset_path, asset_url_path):
-
- return "/".join(
- [
- # Only take the first part of the pathname
- requests_pathname.rstrip("/"),
- asset_url_path,
- asset_path,
- ]
- )
-
-
-def get_relative_path(requests_pathname, path):
- if requests_pathname == "/" and path == "":
- return "/"
- if requests_pathname != "/" and path == "":
- return requests_pathname
- if not path.startswith("/"):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with a leading / are not supported.
- You supplied: {}
- """.format(
- path
- )
- )
- return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
-
-
-def strip_relative_path(requests_pathname, path):
- if path is None:
- return None
- if (
- requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
- ) or (requests_pathname == "/" and not path.startswith("/")):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with requests_pathname_prefix are not supported.
- You supplied: {} and requests_pathname_prefix was {}
- """.format(
- path, requests_pathname
- )
- )
- if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
- path = path.replace(
- # handle the case where the path might be `/my-dash-app`
- # but the requests_pathname_prefix is `/my-dash-app/`
- requests_pathname.rstrip("/"),
- "",
- 1,
- )
- return path.strip("/")
-
-
 # pylint: disable=no-member
 def patch_collections_abc(member):
  return getattr(collections.abc, member)

dash/dash.py

@@ -42,17 +42,15 @@
  AttributeDict,
  format_tag,
  generate_hash,
- get_asset_path,
- get_relative_path,
  inputs_to_dict,
  inputs_to_vals,
  interpolate_str,
  patch_collections_abc,
  split_callback_id,
- strip_relative_path,
  to_json,
 )
 from . import _callback
+from . import _get_paths
 from . import _dash_renderer
 from . import _validate
 from . import _watch
@@ -366,6 +364,8 @@ def __init__(
  "via the Dash constructor"
  )
 
+ _get_paths.CONFIG = self.config
+
  # keep title as a class property for backwards compatibility
  self.title = title
 
@@ -1470,14 +1470,7 @@ def csp_hashes(self, hash_algorithm="sha256"):
  ]
 
  def get_asset_url(self, path):
- if self.config.assets_external_path:
- prefix = self.config.assets_external_path
- else:
- prefix = self.config.requests_pathname_prefix
-
- asset = get_asset_path(prefix, path, self.config.assets_url_path.lstrip("/"))
-
- return asset
+ return _get_paths.app_get_asset_url(self.config, path)
 
  def get_relative_path(self, path):
  """
@@ -1516,9 +1509,9 @@ def display_content(path):
  return chapters.page_2
  ```
  """
-asset = get_relative_path(self.config.requests_pathname_prefix, path)
-
-return asset
+return _get_paths.app_get_relative_path(
+ self.config.requests_pathname_prefix, path
+)
 
  def strip_relative_path(self, path):
  """
@@ -1567,7 +1560,9 @@ def display_content(path):
  `page-1/sub-page-1`
  ```
  """
- return strip_relative_path(self.config.requests_pathname_prefix, path)
+ return _get_paths.app_strip_relative_path(
+ self.config.requests_pathname_prefix, path
+ )
 
  def _setup_dev_tools(self, **kwargs):
  debug = kwargs.get("debug", False)

.circleci/config.yml

@@ -111,7 +111,7 @@ jobs:
  . venv/bin/activate
  set -eo pipefail
  pip install -e . --progress-bar off && pip list | grep dash
- npm install --production && npm run initialize
+ npm install npm run initialize
  npm run build
  npm run lint
  - run:

CHANGELOG.md

@@ -4,6 +4,16 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added 
+- [#1923](https://github.com/plotly/dash/pull/1923):
+- `dash.get_relative_path`
+- `dash.strip_relative_path`
+- `dash.get_asset_url`
+This is similar to `dash.callback` where you don't need the `app` object. It makes it possible to use these
+functions in the `pages` folder of a multi-page app without running into the circular `app` imports issue.
+
+## [2.1.0] - 2022-01-22
+
 ### Changed
 - [#1876](https://github.com/plotly/dash/pull/1876) Delays finalizing `Dash.config` attributes not used in the constructor until `init_app()`.
 - [#1869](https://github.com/plotly/dash/pull/1869), [#1873](https://github.com/plotly/dash/pull/1873) Upgrade Plotly.js to v2.8.3. This includes:

dash/__init__.py

@@ -21,3 +21,8 @@
 from .version import __version__ # noqa: F401,E402
 from ._callback_context import callback_context # noqa: F401,E402
 from ._callback import callback, clientside_callback # noqa: F401,E402
+from ._get_paths import ( # noqa: F401,E402
+ get_asset_url,
+ get_relative_path,
+ strip_relative_path,
+)

dash/_get_paths.py

@@ -0,0 +1,155 @@
+from ._utils import AttributeDict
+from . import exceptions
+
+CONFIG = AttributeDict()
+
+
+def get_asset_url(path):
+ return app_get_asset_url(CONFIG, path)
+
+
+def app_get_asset_url(config, path):
+ if config.assets_external_path:
+ prefix = config.assets_external_path
+ else:
+ prefix = config.requests_pathname_prefix
+ return "/".join(
+ [
+ # Only take the first part of the pathname
+ prefix.rstrip("/"),
+ config.assets_url_path.lstrip("/"),
+ path,
+ ]
+ )
+
+
+def get_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` prefixed before it.
+ Use this function when specifying local URL paths that will work
+ in environments regardless of what `requests_pathname_prefix` is.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name,
+ e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`.
+ This can be used as an alternative to `get_asset_url` as well with
+ `app.get_relative_path('/assets/logo.png')`
+
+ Use this function with `app.strip_relative_path` in callbacks that
+ deal with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ """
+ return app_get_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_get_relative_path(requests_pathname, path):
+ if requests_pathname == "/" and path == "":
+ return "/"
+ if requests_pathname != "/" and path == "":
+ return requests_pathname
+ if not path.startswith("/"):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with a leading / are not supported.
+ You supplied: {}
+ """.format(
+ path
+ )
+ )
+ return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
+
+
+def strip_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` and leading and trailing
+ slashes stripped from it. Also, if None is passed in, None is returned.
+ Use this function with `get_relative_path` in callbacks that deal
+ with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ Note that `chapters.page_1` will be served if the user visits `/page-1`
+ _or_ `/page-1/` since `strip_relative_path` removes the trailing slash.
+
+ Also note that `strip_relative_path` is compatible with
+ `get_relative_path` in environments where `requests_pathname_prefix` set.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name, e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`
+
+ The `pathname` property of `dcc.Location` will return '`/my-dash-app/page-2`'
+ to the callback.
+ In this case, `app.strip_relative_path('/my-dash-app/page-2')`
+ will return `'page-2'`
+
+ For nested URLs, slashes are still included:
+ `app.strip_relative_path('/page-1/sub-page-1/')` will return
+ `page-1/sub-page-1`
+ ```
+ """
+ return app_strip_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_strip_relative_path(requests_pathname, path):
+ if path is None:
+ return None
+ if (
+ requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
+ ) or (requests_pathname == "/" and not path.startswith("/")):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with requests_pathname_prefix are not supported.
+ You supplied: {} and requests_pathname_prefix was {}
+ """.format(
+ path, requests_pathname
+ )
+ )
+ if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
+ path = path.replace(
+ # handle the case where the path might be `/my-dash-app`
+ # but the requests_pathname_prefix is `/my-dash-app/`
+ requests_pathname.rstrip("/"),
+ "",
+ 1,
+ )
+ return path.strip("/")

dash/_utils.py

@@ -9,7 +9,6 @@
 import io
 import json
 from functools import wraps
-from . import exceptions
 
 logger = logging.getLogger()
 
@@ -47,60 +46,6 @@ def generate_hash():
  return str(uuid.uuid4().hex).strip("-")
 
 
-def get_asset_path(requests_pathname, asset_path, asset_url_path):
-
- return "/".join(
- [
- # Only take the first part of the pathname
- requests_pathname.rstrip("/"),
- asset_url_path,
- asset_path,
- ]
- )
-
-
-def get_relative_path(requests_pathname, path):
- if requests_pathname == "/" and path == "":
- return "/"
- if requests_pathname != "/" and path == "":
- return requests_pathname
- if not path.startswith("/"):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with a leading / are not supported.
- You supplied: {}
- """.format(
- path
- )
- )
- return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
-
-
-def strip_relative_path(requests_pathname, path):
- if path is None:
- return None
- if (
- requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
- ) or (requests_pathname == "/" and not path.startswith("/")):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with requests_pathname_prefix are not supported.
- You supplied: {} and requests_pathname_prefix was {}
- """.format(
- path, requests_pathname
- )
- )
- if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
- path = path.replace(
- # handle the case where the path might be `/my-dash-app`
- # but the requests_pathname_prefix is `/my-dash-app/`
- requests_pathname.rstrip("/"),
- "",
- 1,
- )
- return path.strip("/")
-
-
 # pylint: disable=no-member
 def patch_collections_abc(member):
  return getattr(collections.abc, member)

dash/dash.py

@@ -42,17 +42,15 @@
  AttributeDict,
  format_tag,
  generate_hash,
- get_asset_path,
- get_relative_path,
  inputs_to_dict,
  inputs_to_vals,
  interpolate_str,
  patch_collections_abc,
  split_callback_id,
- strip_relative_path,
  to_json,
 )
 from . import _callback
+from . import _get_paths
 from . import _dash_renderer
 from . import _validate
 from . import _watch
@@ -366,6 +364,8 @@ def __init__(
  "via the Dash constructor"
  )
 
+ _get_paths.CONFIG = self.config
+
  # keep title as a class property for backwards compatibility
  self.title = title
 
@@ -1470,14 +1470,7 @@ def csp_hashes(self, hash_algorithm="sha256"):
  ]
 
  def get_asset_url(self, path):
- if self.config.assets_external_path:
- prefix = self.config.assets_external_path
- else:
- prefix = self.config.requests_pathname_prefix
-
- asset = get_asset_path(prefix, path, self.config.assets_url_path.lstrip("/"))
-
- return asset
+ return _get_paths.app_get_asset_url(self.config, path)
 
  def get_relative_path(self, path):
  """
@@ -1516,9 +1509,9 @@ def display_content(path):
  return chapters.page_2
  ```
  """
-asset = get_relative_path(self.config.requests_pathname_prefix, path)
-
-return asset
+return _get_paths.app_get_relative_path(
+ self.config.requests_pathname_prefix, path
+)
 
  def strip_relative_path(self, path):
  """
@@ -1567,7 +1560,9 @@ def display_content(path):
  `page-1/sub-page-1`
  ```
  """
- return strip_relative_path(self.config.requests_pathname_prefix, path)
+ return _get_paths.app_strip_relative_path(
+ self.config.requests_pathname_prefix, path
+ )
 
  def _setup_dev_tools(self, **kwargs):
  debug = kwargs.get("debug", False)

.circleci/config.yml

@@ -111,7 +111,7 @@ jobs:
  . venv/bin/activate
  set -eo pipefail
  pip install -e . --progress-bar off && pip list | grep dash
- npm install --production && npm run initialize
+ npm install npm run initialize
  npm run build
  npm run lint
  - run:

CHANGELOG.md

@@ -4,6 +4,16 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added 
+- [#1923](https://github.com/plotly/dash/pull/1923):
+- `dash.get_relative_path`
+- `dash.strip_relative_path`
+- `dash.get_asset_url`
+This is similar to `dash.callback` where you don't need the `app` object. It makes it possible to use these
+functions in the `pages` folder of a multi-page app without running into the circular `app` imports issue.
+
+## [2.1.0] - 2022-01-22
+
 ### Changed
 - [#1876](https://github.com/plotly/dash/pull/1876) Delays finalizing `Dash.config` attributes not used in the constructor until `init_app()`.
 - [#1869](https://github.com/plotly/dash/pull/1869), [#1873](https://github.com/plotly/dash/pull/1873) Upgrade Plotly.js to v2.8.3. This includes:

dash/__init__.py

@@ -21,3 +21,8 @@
 from .version import __version__ # noqa: F401,E402
 from ._callback_context import callback_context # noqa: F401,E402
 from ._callback import callback, clientside_callback # noqa: F401,E402
+from ._get_paths import ( # noqa: F401,E402
+ get_asset_url,
+ get_relative_path,
+ strip_relative_path,
+)

dash/_get_paths.py

@@ -0,0 +1,155 @@
+from ._utils import AttributeDict
+from . import exceptions
+
+CONFIG = AttributeDict()
+
+
+def get_asset_url(path):
+ return app_get_asset_url(CONFIG, path)
+
+
+def app_get_asset_url(config, path):
+ if config.assets_external_path:
+ prefix = config.assets_external_path
+ else:
+ prefix = config.requests_pathname_prefix
+ return "/".join(
+ [
+ # Only take the first part of the pathname
+ prefix.rstrip("/"),
+ config.assets_url_path.lstrip("/"),
+ path,
+ ]
+ )
+
+
+def get_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` prefixed before it.
+ Use this function when specifying local URL paths that will work
+ in environments regardless of what `requests_pathname_prefix` is.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name,
+ e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`.
+ This can be used as an alternative to `get_asset_url` as well with
+ `app.get_relative_path('/assets/logo.png')`
+
+ Use this function with `app.strip_relative_path` in callbacks that
+ deal with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ """
+ return app_get_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_get_relative_path(requests_pathname, path):
+ if requests_pathname == "/" and path == "":
+ return "/"
+ if requests_pathname != "/" and path == "":
+ return requests_pathname
+ if not path.startswith("/"):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with a leading / are not supported.
+ You supplied: {}
+ """.format(
+ path
+ )
+ )
+ return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
+
+
+def strip_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` and leading and trailing
+ slashes stripped from it. Also, if None is passed in, None is returned.
+ Use this function with `get_relative_path` in callbacks that deal
+ with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ Note that `chapters.page_1` will be served if the user visits `/page-1`
+ _or_ `/page-1/` since `strip_relative_path` removes the trailing slash.
+
+ Also note that `strip_relative_path` is compatible with
+ `get_relative_path` in environments where `requests_pathname_prefix` set.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name, e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`
+
+ The `pathname` property of `dcc.Location` will return '`/my-dash-app/page-2`'
+ to the callback.
+ In this case, `app.strip_relative_path('/my-dash-app/page-2')`
+ will return `'page-2'`
+
+ For nested URLs, slashes are still included:
+ `app.strip_relative_path('/page-1/sub-page-1/')` will return
+ `page-1/sub-page-1`
+ ```
+ """
+ return app_strip_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_strip_relative_path(requests_pathname, path):
+ if path is None:
+ return None
+ if (
+ requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
+ ) or (requests_pathname == "/" and not path.startswith("/")):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with requests_pathname_prefix are not supported.
+ You supplied: {} and requests_pathname_prefix was {}
+ """.format(
+ path, requests_pathname
+ )
+ )
+ if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
+ path = path.replace(
+ # handle the case where the path might be `/my-dash-app`
+ # but the requests_pathname_prefix is `/my-dash-app/`
+ requests_pathname.rstrip("/"),
+ "",
+ 1,
+ )
+ return path.strip("/")

dash/_utils.py

@@ -9,7 +9,6 @@
 import io
 import json
 from functools import wraps
-from . import exceptions
 
 logger = logging.getLogger()
 
@@ -47,60 +46,6 @@ def generate_hash():
  return str(uuid.uuid4().hex).strip("-")
 
 
-def get_asset_path(requests_pathname, asset_path, asset_url_path):
-
- return "/".join(
- [
- # Only take the first part of the pathname
- requests_pathname.rstrip("/"),
- asset_url_path,
- asset_path,
- ]
- )
-
-
-def get_relative_path(requests_pathname, path):
- if requests_pathname == "/" and path == "":
- return "/"
- if requests_pathname != "/" and path == "":
- return requests_pathname
- if not path.startswith("/"):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with a leading / are not supported.
- You supplied: {}
- """.format(
- path
- )
- )
- return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
-
-
-def strip_relative_path(requests_pathname, path):
- if path is None:
- return None
- if (
- requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
- ) or (requests_pathname == "/" and not path.startswith("/")):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with requests_pathname_prefix are not supported.
- You supplied: {} and requests_pathname_prefix was {}
- """.format(
- path, requests_pathname
- )
- )
- if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
- path = path.replace(
- # handle the case where the path might be `/my-dash-app`
- # but the requests_pathname_prefix is `/my-dash-app/`
- requests_pathname.rstrip("/"),
- "",
- 1,
- )
- return path.strip("/")
-
-
 # pylint: disable=no-member
 def patch_collections_abc(member):
  return getattr(collections.abc, member)

dash/dash.py

@@ -42,17 +42,15 @@
  AttributeDict,
  format_tag,
  generate_hash,
- get_asset_path,
- get_relative_path,
  inputs_to_dict,
  inputs_to_vals,
  interpolate_str,
  patch_collections_abc,
  split_callback_id,
- strip_relative_path,
  to_json,
 )
 from . import _callback
+from . import _get_paths
 from . import _dash_renderer
 from . import _validate
 from . import _watch
@@ -366,6 +364,8 @@ def __init__(
  "via the Dash constructor"
  )
 
+ _get_paths.CONFIG = self.config
+
  # keep title as a class property for backwards compatibility
  self.title = title
 
@@ -1470,14 +1470,7 @@ def csp_hashes(self, hash_algorithm="sha256"):
  ]
 
  def get_asset_url(self, path):
- if self.config.assets_external_path:
- prefix = self.config.assets_external_path
- else:
- prefix = self.config.requests_pathname_prefix
-
- asset = get_asset_path(prefix, path, self.config.assets_url_path.lstrip("/"))
-
- return asset
+ return _get_paths.app_get_asset_url(self.config, path)
 
  def get_relative_path(self, path):
  """
@@ -1516,9 +1509,9 @@ def display_content(path):
  return chapters.page_2
  ```
  """
-asset = get_relative_path(self.config.requests_pathname_prefix, path)
-
-return asset
+return _get_paths.app_get_relative_path(
+ self.config.requests_pathname_prefix, path
+)
 
  def strip_relative_path(self, path):
  """
@@ -1567,7 +1560,9 @@ def display_content(path):
  `page-1/sub-page-1`
  ```
  """
- return strip_relative_path(self.config.requests_pathname_prefix, path)
+ return _get_paths.app_strip_relative_path(
+ self.config.requests_pathname_prefix, path
+ )
 
  def _setup_dev_tools(self, **kwargs):
  debug = kwargs.get("debug", False)

.circleci/config.yml

@@ -111,7 +111,7 @@ jobs:
  . venv/bin/activate
  set -eo pipefail
  pip install -e . --progress-bar off && pip list | grep dash
- npm install --production && npm run initialize
+ npm install npm run initialize
  npm run build
  npm run lint
  - run:

CHANGELOG.md

@@ -4,6 +4,16 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added 
+- [#1923](https://github.com/plotly/dash/pull/1923):
+- `dash.get_relative_path`
+- `dash.strip_relative_path`
+- `dash.get_asset_url`
+This is similar to `dash.callback` where you don't need the `app` object. It makes it possible to use these
+functions in the `pages` folder of a multi-page app without running into the circular `app` imports issue.
+
+## [2.1.0] - 2022-01-22
+
 ### Changed
 - [#1876](https://github.com/plotly/dash/pull/1876) Delays finalizing `Dash.config` attributes not used in the constructor until `init_app()`.
 - [#1869](https://github.com/plotly/dash/pull/1869), [#1873](https://github.com/plotly/dash/pull/1873) Upgrade Plotly.js to v2.8.3. This includes:

dash/__init__.py

@@ -21,3 +21,8 @@
 from .version import __version__ # noqa: F401,E402
 from ._callback_context import callback_context # noqa: F401,E402
 from ._callback import callback, clientside_callback # noqa: F401,E402
+from ._get_paths import ( # noqa: F401,E402
+ get_asset_url,
+ get_relative_path,
+ strip_relative_path,
+)

dash/_get_paths.py

@@ -0,0 +1,155 @@
+from ._utils import AttributeDict
+from . import exceptions
+
+CONFIG = AttributeDict()
+
+
+def get_asset_url(path):
+ return app_get_asset_url(CONFIG, path)
+
+
+def app_get_asset_url(config, path):
+ if config.assets_external_path:
+ prefix = config.assets_external_path
+ else:
+ prefix = config.requests_pathname_prefix
+ return "/".join(
+ [
+ # Only take the first part of the pathname
+ prefix.rstrip("/"),
+ config.assets_url_path.lstrip("/"),
+ path,
+ ]
+ )
+
+
+def get_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` prefixed before it.
+ Use this function when specifying local URL paths that will work
+ in environments regardless of what `requests_pathname_prefix` is.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name,
+ e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`.
+ This can be used as an alternative to `get_asset_url` as well with
+ `app.get_relative_path('/assets/logo.png')`
+
+ Use this function with `app.strip_relative_path` in callbacks that
+ deal with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ """
+ return app_get_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_get_relative_path(requests_pathname, path):
+ if requests_pathname == "/" and path == "":
+ return "/"
+ if requests_pathname != "/" and path == "":
+ return requests_pathname
+ if not path.startswith("/"):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with a leading / are not supported.
+ You supplied: {}
+ """.format(
+ path
+ )
+ )
+ return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
+
+
+def strip_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` and leading and trailing
+ slashes stripped from it. Also, if None is passed in, None is returned.
+ Use this function with `get_relative_path` in callbacks that deal
+ with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ Note that `chapters.page_1` will be served if the user visits `/page-1`
+ _or_ `/page-1/` since `strip_relative_path` removes the trailing slash.
+
+ Also note that `strip_relative_path` is compatible with
+ `get_relative_path` in environments where `requests_pathname_prefix` set.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name, e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`
+
+ The `pathname` property of `dcc.Location` will return '`/my-dash-app/page-2`'
+ to the callback.
+ In this case, `app.strip_relative_path('/my-dash-app/page-2')`
+ will return `'page-2'`
+
+ For nested URLs, slashes are still included:
+ `app.strip_relative_path('/page-1/sub-page-1/')` will return
+ `page-1/sub-page-1`
+ ```
+ """
+ return app_strip_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_strip_relative_path(requests_pathname, path):
+ if path is None:
+ return None
+ if (
+ requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
+ ) or (requests_pathname == "/" and not path.startswith("/")):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with requests_pathname_prefix are not supported.
+ You supplied: {} and requests_pathname_prefix was {}
+ """.format(
+ path, requests_pathname
+ )
+ )
+ if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
+ path = path.replace(
+ # handle the case where the path might be `/my-dash-app`
+ # but the requests_pathname_prefix is `/my-dash-app/`
+ requests_pathname.rstrip("/"),
+ "",
+ 1,
+ )
+ return path.strip("/")

dash/_utils.py

@@ -9,7 +9,6 @@
 import io
 import json
 from functools import wraps
-from . import exceptions
 
 logger = logging.getLogger()
 
@@ -47,60 +46,6 @@ def generate_hash():
  return str(uuid.uuid4().hex).strip("-")
 
 
-def get_asset_path(requests_pathname, asset_path, asset_url_path):
-
- return "/".join(
- [
- # Only take the first part of the pathname
- requests_pathname.rstrip("/"),
- asset_url_path,
- asset_path,
- ]
- )
-
-
-def get_relative_path(requests_pathname, path):
- if requests_pathname == "/" and path == "":
- return "/"
- if requests_pathname != "/" and path == "":
- return requests_pathname
- if not path.startswith("/"):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with a leading / are not supported.
- You supplied: {}
- """.format(
- path
- )
- )
- return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
-
-
-def strip_relative_path(requests_pathname, path):
- if path is None:
- return None
- if (
- requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
- ) or (requests_pathname == "/" and not path.startswith("/")):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with requests_pathname_prefix are not supported.
- You supplied: {} and requests_pathname_prefix was {}
- """.format(
- path, requests_pathname
- )
- )
- if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
- path = path.replace(
- # handle the case where the path might be `/my-dash-app`
- # but the requests_pathname_prefix is `/my-dash-app/`
- requests_pathname.rstrip("/"),
- "",
- 1,
- )
- return path.strip("/")
-
-
 # pylint: disable=no-member
 def patch_collections_abc(member):
  return getattr(collections.abc, member)

dash/dash.py

@@ -42,17 +42,15 @@
  AttributeDict,
  format_tag,
  generate_hash,
- get_asset_path,
- get_relative_path,
  inputs_to_dict,
  inputs_to_vals,
  interpolate_str,
  patch_collections_abc,
  split_callback_id,
- strip_relative_path,
  to_json,
 )
 from . import _callback
+from . import _get_paths
 from . import _dash_renderer
 from . import _validate
 from . import _watch
@@ -366,6 +364,8 @@ def __init__(
  "via the Dash constructor"
  )
 
+ _get_paths.CONFIG = self.config
+
  # keep title as a class property for backwards compatibility
  self.title = title
 
@@ -1470,14 +1470,7 @@ def csp_hashes(self, hash_algorithm="sha256"):
  ]
 
  def get_asset_url(self, path):
- if self.config.assets_external_path:
- prefix = self.config.assets_external_path
- else:
- prefix = self.config.requests_pathname_prefix
-
- asset = get_asset_path(prefix, path, self.config.assets_url_path.lstrip("/"))
-
- return asset
+ return _get_paths.app_get_asset_url(self.config, path)
 
  def get_relative_path(self, path):
  """
@@ -1516,9 +1509,9 @@ def display_content(path):
  return chapters.page_2
  ```
  """
-asset = get_relative_path(self.config.requests_pathname_prefix, path)
-
-return asset
+return _get_paths.app_get_relative_path(
+ self.config.requests_pathname_prefix, path
+)
 
  def strip_relative_path(self, path):
  """
@@ -1567,7 +1560,9 @@ def display_content(path):
  `page-1/sub-page-1`
  ```
  """
- return strip_relative_path(self.config.requests_pathname_prefix, path)
+ return _get_paths.app_strip_relative_path(
+ self.config.requests_pathname_prefix, path
+ )
 
  def _setup_dev_tools(self, **kwargs):
  debug = kwargs.get("debug", False)

.circleci/config.yml

@@ -111,7 +111,7 @@ jobs:
  . venv/bin/activate
  set -eo pipefail
  pip install -e . --progress-bar off && pip list | grep dash
- npm install --production && npm run initialize
+ npm install npm run initialize
  npm run build
  npm run lint
  - run:

CHANGELOG.md

@@ -4,6 +4,16 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added 
+- [#1923](https://github.com/plotly/dash/pull/1923):
+- `dash.get_relative_path`
+- `dash.strip_relative_path`
+- `dash.get_asset_url`
+This is similar to `dash.callback` where you don't need the `app` object. It makes it possible to use these
+functions in the `pages` folder of a multi-page app without running into the circular `app` imports issue.
+
+## [2.1.0] - 2022-01-22
+
 ### Changed
 - [#1876](https://github.com/plotly/dash/pull/1876) Delays finalizing `Dash.config` attributes not used in the constructor until `init_app()`.
 - [#1869](https://github.com/plotly/dash/pull/1869), [#1873](https://github.com/plotly/dash/pull/1873) Upgrade Plotly.js to v2.8.3. This includes:

dash/__init__.py

@@ -21,3 +21,8 @@
 from .version import __version__ # noqa: F401,E402
 from ._callback_context import callback_context # noqa: F401,E402
 from ._callback import callback, clientside_callback # noqa: F401,E402
+from ._get_paths import ( # noqa: F401,E402
+ get_asset_url,
+ get_relative_path,
+ strip_relative_path,
+)

dash/_get_paths.py

@@ -0,0 +1,155 @@
+from ._utils import AttributeDict
+from . import exceptions
+
+CONFIG = AttributeDict()
+
+
+def get_asset_url(path):
+ return app_get_asset_url(CONFIG, path)
+
+
+def app_get_asset_url(config, path):
+ if config.assets_external_path:
+ prefix = config.assets_external_path
+ else:
+ prefix = config.requests_pathname_prefix
+ return "/".join(
+ [
+ # Only take the first part of the pathname
+ prefix.rstrip("/"),
+ config.assets_url_path.lstrip("/"),
+ path,
+ ]
+ )
+
+
+def get_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` prefixed before it.
+ Use this function when specifying local URL paths that will work
+ in environments regardless of what `requests_pathname_prefix` is.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name,
+ e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`.
+ This can be used as an alternative to `get_asset_url` as well with
+ `app.get_relative_path('/assets/logo.png')`
+
+ Use this function with `app.strip_relative_path` in callbacks that
+ deal with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ """
+ return app_get_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_get_relative_path(requests_pathname, path):
+ if requests_pathname == "/" and path == "":
+ return "/"
+ if requests_pathname != "/" and path == "":
+ return requests_pathname
+ if not path.startswith("/"):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with a leading / are not supported.
+ You supplied: {}
+ """.format(
+ path
+ )
+ )
+ return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
+
+
+def strip_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` and leading and trailing
+ slashes stripped from it. Also, if None is passed in, None is returned.
+ Use this function with `get_relative_path` in callbacks that deal
+ with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ Note that `chapters.page_1` will be served if the user visits `/page-1`
+ _or_ `/page-1/` since `strip_relative_path` removes the trailing slash.
+
+ Also note that `strip_relative_path` is compatible with
+ `get_relative_path` in environments where `requests_pathname_prefix` set.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name, e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`
+
+ The `pathname` property of `dcc.Location` will return '`/my-dash-app/page-2`'
+ to the callback.
+ In this case, `app.strip_relative_path('/my-dash-app/page-2')`
+ will return `'page-2'`
+
+ For nested URLs, slashes are still included:
+ `app.strip_relative_path('/page-1/sub-page-1/')` will return
+ `page-1/sub-page-1`
+ ```
+ """
+ return app_strip_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_strip_relative_path(requests_pathname, path):
+ if path is None:
+ return None
+ if (
+ requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
+ ) or (requests_pathname == "/" and not path.startswith("/")):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with requests_pathname_prefix are not supported.
+ You supplied: {} and requests_pathname_prefix was {}
+ """.format(
+ path, requests_pathname
+ )
+ )
+ if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
+ path = path.replace(
+ # handle the case where the path might be `/my-dash-app`
+ # but the requests_pathname_prefix is `/my-dash-app/`
+ requests_pathname.rstrip("/"),
+ "",
+ 1,
+ )
+ return path.strip("/")

dash/_utils.py

@@ -9,7 +9,6 @@
 import io
 import json
 from functools import wraps
-from . import exceptions
 
 logger = logging.getLogger()
 
@@ -47,60 +46,6 @@ def generate_hash():
  return str(uuid.uuid4().hex).strip("-")
 
 
-def get_asset_path(requests_pathname, asset_path, asset_url_path):
-
- return "/".join(
- [
- # Only take the first part of the pathname
- requests_pathname.rstrip("/"),
- asset_url_path,
- asset_path,
- ]
- )
-
-
-def get_relative_path(requests_pathname, path):
- if requests_pathname == "/" and path == "":
- return "/"
- if requests_pathname != "/" and path == "":
- return requests_pathname
- if not path.startswith("/"):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with a leading / are not supported.
- You supplied: {}
- """.format(
- path
- )
- )
- return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
-
-
-def strip_relative_path(requests_pathname, path):
- if path is None:
- return None
- if (
- requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
- ) or (requests_pathname == "/" and not path.startswith("/")):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with requests_pathname_prefix are not supported.
- You supplied: {} and requests_pathname_prefix was {}
- """.format(
- path, requests_pathname
- )
- )
- if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
- path = path.replace(
- # handle the case where the path might be `/my-dash-app`
- # but the requests_pathname_prefix is `/my-dash-app/`
- requests_pathname.rstrip("/"),
- "",
- 1,
- )
- return path.strip("/")
-
-
 # pylint: disable=no-member
 def patch_collections_abc(member):
  return getattr(collections.abc, member)

dash/dash.py

@@ -42,17 +42,15 @@
  AttributeDict,
  format_tag,
  generate_hash,
- get_asset_path,
- get_relative_path,
  inputs_to_dict,
  inputs_to_vals,
  interpolate_str,
  patch_collections_abc,
  split_callback_id,
- strip_relative_path,
  to_json,
 )
 from . import _callback
+from . import _get_paths
 from . import _dash_renderer
 from . import _validate
 from . import _watch
@@ -366,6 +364,8 @@ def __init__(
  "via the Dash constructor"
  )
 
+ _get_paths.CONFIG = self.config
+
  # keep title as a class property for backwards compatibility
  self.title = title
 
@@ -1470,14 +1470,7 @@ def csp_hashes(self, hash_algorithm="sha256"):
  ]
 
  def get_asset_url(self, path):
- if self.config.assets_external_path:
- prefix = self.config.assets_external_path
- else:
- prefix = self.config.requests_pathname_prefix
-
- asset = get_asset_path(prefix, path, self.config.assets_url_path.lstrip("/"))
-
- return asset
+ return _get_paths.app_get_asset_url(self.config, path)
 
  def get_relative_path(self, path):
  """
@@ -1516,9 +1509,9 @@ def display_content(path):
  return chapters.page_2
  ```
  """
-asset = get_relative_path(self.config.requests_pathname_prefix, path)
-
-return asset
+return _get_paths.app_get_relative_path(
+ self.config.requests_pathname_prefix, path
+)
 
  def strip_relative_path(self, path):
  """
@@ -1567,7 +1560,9 @@ def display_content(path):
  `page-1/sub-page-1`
  ```
  """
- return strip_relative_path(self.config.requests_pathname_prefix, path)
+ return _get_paths.app_strip_relative_path(
+ self.config.requests_pathname_prefix, path
+ )
 
  def _setup_dev_tools(self, **kwargs):
  debug = kwargs.get("debug", False)

.circleci/config.yml

@@ -111,7 +111,7 @@ jobs:
  . venv/bin/activate
  set -eo pipefail
  pip install -e . --progress-bar off && pip list | grep dash
- npm install --production && npm run initialize
+ npm install npm run initialize
  npm run build
  npm run lint
  - run:

CHANGELOG.md

@@ -4,6 +4,16 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+### Added 
+- [#1923](https://github.com/plotly/dash/pull/1923):
+- `dash.get_relative_path`
+- `dash.strip_relative_path`
+- `dash.get_asset_url`
+This is similar to `dash.callback` where you don't need the `app` object. It makes it possible to use these
+functions in the `pages` folder of a multi-page app without running into the circular `app` imports issue.
+
+## [2.1.0] - 2022-01-22
+
 ### Changed
 - [#1876](https://github.com/plotly/dash/pull/1876) Delays finalizing `Dash.config` attributes not used in the constructor until `init_app()`.
 - [#1869](https://github.com/plotly/dash/pull/1869), [#1873](https://github.com/plotly/dash/pull/1873) Upgrade Plotly.js to v2.8.3. This includes:

dash/__init__.py

@@ -21,3 +21,8 @@
 from .version import __version__ # noqa: F401,E402
 from ._callback_context import callback_context # noqa: F401,E402
 from ._callback import callback, clientside_callback # noqa: F401,E402
+from ._get_paths import ( # noqa: F401,E402
+ get_asset_url,
+ get_relative_path,
+ strip_relative_path,
+)

dash/_get_paths.py

@@ -0,0 +1,155 @@
+from ._utils import AttributeDict
+from . import exceptions
+
+CONFIG = AttributeDict()
+
+
+def get_asset_url(path):
+ return app_get_asset_url(CONFIG, path)
+
+
+def app_get_asset_url(config, path):
+ if config.assets_external_path:
+ prefix = config.assets_external_path
+ else:
+ prefix = config.requests_pathname_prefix
+ return "/".join(
+ [
+ # Only take the first part of the pathname
+ prefix.rstrip("/"),
+ config.assets_url_path.lstrip("/"),
+ path,
+ ]
+ )
+
+
+def get_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` prefixed before it.
+ Use this function when specifying local URL paths that will work
+ in environments regardless of what `requests_pathname_prefix` is.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name,
+ e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`.
+ This can be used as an alternative to `get_asset_url` as well with
+ `app.get_relative_path('/assets/logo.png')`
+
+ Use this function with `app.strip_relative_path` in callbacks that
+ deal with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ """
+ return app_get_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_get_relative_path(requests_pathname, path):
+ if requests_pathname == "/" and path == "":
+ return "/"
+ if requests_pathname != "/" and path == "":
+ return requests_pathname
+ if not path.startswith("/"):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with a leading / are not supported.
+ You supplied: {}
+ """.format(
+ path
+ )
+ )
+ return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
+
+
+def strip_relative_path(path):
+ """
+ Return a path with `requests_pathname_prefix` and leading and trailing
+ slashes stripped from it. Also, if None is passed in, None is returned.
+ Use this function with `get_relative_path` in callbacks that deal
+ with `dcc.Location` `pathname` routing.
+ That is, your usage may look like:
+ ```
+ app.layout = html.Div([
+ dcc.Location(id='url'),
+ html.Div(id='content')
+ ])
+ @app.callback(Output('content', 'children'), [Input('url', 'pathname')])
+ def display_content(path):
+ page_name = app.strip_relative_path(path)
+ if not page_name: # None or ''
+ return html.Div([
+ dcc.Link(href=app.get_relative_path('/page-1')),
+ dcc.Link(href=app.get_relative_path('/page-2')),
+ ])
+ elif page_name == 'page-1':
+ return chapters.page_1
+ if page_name == "page-2":
+ return chapters.page_2
+ ```
+ Note that `chapters.page_1` will be served if the user visits `/page-1`
+ _or_ `/page-1/` since `strip_relative_path` removes the trailing slash.
+
+ Also note that `strip_relative_path` is compatible with
+ `get_relative_path` in environments where `requests_pathname_prefix` set.
+ In some deployment environments, like Dash Enterprise,
+ `requests_pathname_prefix` is set to the application name, e.g. `my-dash-app`.
+ When working locally, `requests_pathname_prefix` might be unset and
+ so a relative URL like `/page-2` can just be `/page-2`.
+ However, when the app is deployed to a URL like `/my-dash-app`, then
+ `app.get_relative_path('/page-2')` will return `/my-dash-app/page-2`
+
+ The `pathname` property of `dcc.Location` will return '`/my-dash-app/page-2`'
+ to the callback.
+ In this case, `app.strip_relative_path('/my-dash-app/page-2')`
+ will return `'page-2'`
+
+ For nested URLs, slashes are still included:
+ `app.strip_relative_path('/page-1/sub-page-1/')` will return
+ `page-1/sub-page-1`
+ ```
+ """
+ return app_strip_relative_path(CONFIG.requests_pathname_prefix, path)
+
+
+def app_strip_relative_path(requests_pathname, path):
+ if path is None:
+ return None
+ if (
+ requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
+ ) or (requests_pathname == "/" and not path.startswith("/")):
+ raise exceptions.UnsupportedRelativePath(
+ """
+ Paths that aren't prefixed with requests_pathname_prefix are not supported.
+ You supplied: {} and requests_pathname_prefix was {}
+ """.format(
+ path, requests_pathname
+ )
+ )
+ if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
+ path = path.replace(
+ # handle the case where the path might be `/my-dash-app`
+ # but the requests_pathname_prefix is `/my-dash-app/`
+ requests_pathname.rstrip("/"),
+ "",
+ 1,
+ )
+ return path.strip("/")

dash/_utils.py

@@ -9,7 +9,6 @@
 import io
 import json
 from functools import wraps
-from . import exceptions
 
 logger = logging.getLogger()
 
@@ -47,60 +46,6 @@ def generate_hash():
  return str(uuid.uuid4().hex).strip("-")
 
 
-def get_asset_path(requests_pathname, asset_path, asset_url_path):
-
- return "/".join(
- [
- # Only take the first part of the pathname
- requests_pathname.rstrip("/"),
- asset_url_path,
- asset_path,
- ]
- )
-
-
-def get_relative_path(requests_pathname, path):
- if requests_pathname == "/" and path == "":
- return "/"
- if requests_pathname != "/" and path == "":
- return requests_pathname
- if not path.startswith("/"):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with a leading / are not supported.
- You supplied: {}
- """.format(
- path
- )
- )
- return "/".join([requests_pathname.rstrip("/"), path.lstrip("/")])
-
-
-def strip_relative_path(requests_pathname, path):
- if path is None:
- return None
- if (
- requests_pathname != "/" and not path.startswith(requests_pathname.rstrip("/"))
- ) or (requests_pathname == "/" and not path.startswith("/")):
- raise exceptions.UnsupportedRelativePath(
- """
- Paths that aren't prefixed with requests_pathname_prefix are not supported.
- You supplied: {} and requests_pathname_prefix was {}
- """.format(
- path, requests_pathname
- )
- )
- if requests_pathname != "/" and path.startswith(requests_pathname.rstrip("/")):
- path = path.replace(
- # handle the case where the path might be `/my-dash-app`
- # but the requests_pathname_prefix is `/my-dash-app/`
- requests_pathname.rstrip("/"),
- "",
- 1,
- )
- return path.strip("/")
-
-
 # pylint: disable=no-member
 def patch_collections_abc(member):
  return getattr(collections.abc, member)

dash/dash.py

@@ -42,17 +42,15 @@
  AttributeDict,
  format_tag,
  generate_hash,
- get_asset_path,
- get_relative_path,
  inputs_to_dict,
  inputs_to_vals,
  interpolate_str,
  patch_collections_abc,
  split_callback_id,
- strip_relative_path,
  to_json,
 )
 from . import _callback
+from . import _get_paths
 from . import _dash_renderer
 from . import _validate
 from . import _watch
@@ -366,6 +364,8 @@ def __init__(
  "via the Dash constructor"
  )
 
+ _get_paths.CONFIG = self.config
+
  # keep title as a class property for backwards compatibility
  self.title = title
 
@@ -1470,14 +1470,7 @@ def csp_hashes(self, hash_algorithm="sha256"):
  ]
 
  def get_asset_url(self, path):
- if self.config.assets_external_path:
- prefix = self.config.assets_external_path
- else:
- prefix = self.config.requests_pathname_prefix
-
- asset = get_asset_path(prefix, path, self.config.assets_url_path.lstrip("/"))
-
- return asset
+ return _get_paths.app_get_asset_url(self.config, path)
 
  def get_relative_path(self, path):
  """
@@ -1516,9 +1509,9 @@ def display_content(path):
  return chapters.page_2
  ```
  """
-asset = get_relative_path(self.config.requests_pathname_prefix, path)
-
-return asset
+return _get_paths.app_get_relative_path(
+ self.config.requests_pathname_prefix, path
+)
 
  def strip_relative_path(self, path):
  """
@@ -1567,7 +1560,9 @@ def display_content(path):
  `page-1/sub-page-1`
  ```
  """
- return strip_relative_path(self.config.requests_pathname_prefix, path)
+ return _get_paths.app_strip_relative_path(
+ self.config.requests_pathname_prefix, path
+ )
 
  def _setup_dev_tools(self, **kwargs):
  debug = kwargs.get("debug", False)