import functools
import os
import sys
import collections
import importlib
import warnings
from contextvars import copy_context
from importlib.machinery import ModuleSpec
import pkgutil
import threading
import re
import logging
import time
import mimetypes
import hashlib
import base64
import traceback
from urllib.parse import urlparse
from typing import Dict, Optional, Union
import flask
from importlib_metadata import version as _get_distribution_version
from dash import dcc
from dash import html
from dash import dash_table
from .fingerprint import build_fingerprint, check_fingerprint
from .resources import Scripts, Css
from .dependencies import (
Input,
Output,
State,
)
from .development.base_component import ComponentRegistry
from .exceptions import (
PreventUpdate,
InvalidResourceError,
ProxyError,
DuplicateCallback,
)
from .version import __version__
from ._configs import get_combined_config, pathname_configs, pages_folder_config
from ._utils import (
AttributeDict,
format_tag,
generate_hash,
inputs_to_dict,
inputs_to_vals,
interpolate_str,
patch_collections_abc,
split_callback_id,
to_json,
convert_to_AttributeDict,
gen_salt,
hooks_to_js_object,
parse_version,
get_caller_name,
)
from . import _callback
from . import _get_paths
from . import _dash_renderer
from . import _validate
from . import _watch
from . import _get_app
from ._grouping import map_grouping, grouping_len, update_args_group
from . import _pages
from ._pages import (
_parse_query_string,
_page_meta_tags,
_path_to_page,
_import_layouts_from_pages,
)
from ._jupyter import jupyter_dash, JupyterDisplayMode
from .types import RendererHooks
# Add explicit mapping for map files
mimetypes.add_type("application/json", ".map", True)
_default_index = """
{%metas%}
{%title%}
{%favicon%}
{%css%}
{%app_entry%}
"""
_app_entry = """
Loading...
"""
_re_index_entry = "{%app_entry%}", "{%app_entry%}"
_re_index_config = "{%config%}", "{%config%}"
_re_index_scripts = "{%scripts%}", "{%scripts%}"
_re_index_entry_id = 'id="react-entry-point"', "#react-entry-point"
_re_index_config_id = 'id="_dash-config"', "#_dash-config"
_re_index_scripts_id = 'src="[^"]*dash[-_]renderer[^"]*"', "dash-renderer"
_re_renderer_scripts_id = 'id="_dash-renderer', "new DashRenderer"
_ID_CONTENT = "_pages_content"
_ID_LOCATION = "_pages_location"
_ID_STORE = "_pages_store"
_ID_DUMMY = "_pages_dummy"
# Handles the case in a newly cloned environment where the components are not yet generated.
try:
page_container = html.Div(
[
dcc.Location(id=_ID_LOCATION, refresh="callback-nav"),
html.Div(id=_ID_CONTENT, disable_n_clicks=True),
dcc.Store(id=_ID_STORE),
html.Div(id=_ID_DUMMY, disable_n_clicks=True),
]
)
# pylint: disable-next=bare-except
except: # noqa: E722
page_container = None
def _get_traceback(secret, error: Exception):
try:
# pylint: disable=import-outside-toplevel
from werkzeug.debug import tbtools
except ImportError:
tbtools = None
def _get_skip(text, divider=2):
skip = 0
for i, line in enumerate(text):
if "%% callback invoked %%" in line:
skip = int((i + 1) / divider)
break
return skip
# werkzeug<2.1.0
if hasattr(tbtools, "get_current_traceback"):
tb = tbtools.get_current_traceback()
skip = _get_skip(tb.plaintext.splitlines())
return tbtools.get_current_traceback(skip=skip).render_full()
if hasattr(tbtools, "DebugTraceback"):
tb = tbtools.DebugTraceback(error) # pylint: disable=no-member
skip = _get_skip(tb.render_traceback_text().splitlines())
# pylint: disable=no-member
return tbtools.DebugTraceback(error, skip=skip).render_debugger_html(
True, secret, True
)
tb = traceback.format_exception(type(error), error, error.__traceback__)
skip = _get_skip(tb, 1)
return tb[0] + "".join(tb[skip:])
# Singleton signal to not update an output, alternative to PreventUpdate
no_update = _callback.NoUpdate() # pylint: disable=protected-access
# pylint: disable=too-many-instance-attributes
# pylint: disable=too-many-arguments, too-many-locals
class Dash:
"""Dash is a framework for building analytical web applications.
No JavaScript required.
If a parameter can be set by an environment variable, that is listed as:
env: ``DASH_****``
Values provided here take precedence over environment variables.
:param name: The name Flask should use for your app. Even if you provide
your own ``server``, ``name`` will be used to help find assets.
Typically ``__name__`` (the magic global var, not a string) is the
best value to use. Default ``'__main__'``, env: ``DASH_APP_NAME``
:type name: string
:param server: Sets the Flask server for your app. There are three options:
``True`` (default): Dash will create a new server
``False``: The server will be added later via ``app.init_app(server)``
where ``server`` is a ``flask.Flask`` instance.
``flask.Flask``: use this pre-existing Flask server.
:type server: boolean or flask.Flask
:param assets_folder: a path, relative to the current working directory,
for extra files to be used in the browser. Default ``'assets'``.
All .js and .css files will be loaded immediately unless excluded by
``assets_ignore``, and other files such as images will be served if
requested.
:type assets_folder: string
:param pages_folder: a relative or absolute path for pages of a multi-page app.
Default ``'pages'``.
:type pages_folder: string or pathlib.Path
:param use_pages: When True, the ``pages`` feature for multi-page apps is
enabled. If you set a non-default ``pages_folder`` this will be inferred
to be True. Default `None`.
:type use_pages: boolean
:param include_pages_meta: Include the page meta tags for twitter cards.
:type include_pages_meta: bool
:param assets_url_path: The local urls for assets will be:
``requests_pathname_prefix + assets_url_path + '/' + asset_path``
where ``asset_path`` is the path to a file inside ``assets_folder``.
Default ``'assets'``.
:type asset_url_path: string
:param assets_ignore: A regex, as a string to pass to ``re.compile``, for
assets to omit from immediate loading. Ignored files will still be
served if specifically requested. You cannot use this to prevent access
to sensitive files.
:type assets_ignore: string
:param assets_external_path: an absolute URL from which to load assets.
Use with ``serve_locally=False``. assets_external_path is joined
with assets_url_path to determine the absolute url to the
asset folder. Dash can still find js and css to automatically load
if you also keep local copies in your assets folder that Dash can index,
but external serving can improve performance and reduce load on
the Dash server.
env: ``DASH_ASSETS_EXTERNAL_PATH``
:type assets_external_path: string
:param include_assets_files: Default ``True``, set to ``False`` to prevent
immediate loading of any assets. Assets will still be served if
specifically requested. You cannot use this to prevent access
to sensitive files. env: ``DASH_INCLUDE_ASSETS_FILES``
:type include_assets_files: boolean
:param url_base_pathname: A local URL prefix to use app-wide.
Default ``'/'``. Both `requests_pathname_prefix` and
`routes_pathname_prefix` default to `url_base_pathname`.
env: ``DASH_URL_BASE_PATHNAME``
:type url_base_pathname: string
:param requests_pathname_prefix: A local URL prefix for file requests.
Defaults to `url_base_pathname`, and must end with
`routes_pathname_prefix`. env: ``DASH_REQUESTS_PATHNAME_PREFIX``
:type requests_pathname_prefix: string
:param routes_pathname_prefix: A local URL prefix for JSON requests.
Defaults to ``url_base_pathname``, and must start and end
with ``'/'``. env: ``DASH_ROUTES_PATHNAME_PREFIX``
:type routes_pathname_prefix: string
:param serve_locally: If ``True`` (default), assets and dependencies
(Dash and Component js and css) will be served from local URLs.
If ``False`` we will use CDN links where available.
:type serve_locally: boolean
:param compress: Use gzip to compress files and data served by Flask.
To use this option, you need to install dash[compress]
Default ``False``
:type compress: boolean
:param meta_tags: html tags to be added to the index page.
Each dict should have the attributes and values for one tag, eg:
``{'name': 'description', 'content': 'My App'}``
:type meta_tags: list of dicts
:param index_string: Override the standard Dash index page.
Must contain the correct insertion markers to interpolate various
content into it depending on the app config and components used.
See https://dash.plotly.com/external-resources for details.
:type index_string: string
:param external_scripts: Additional JS files to load with the page.
Each entry can be a string (the URL) or a dict with ``src`` (the URL)
and optionally other ``'
for src in srcs
]
+ [f"" for src in self._inline_scripts]
)
def _generate_config_html(self):
return f''
def _generate_renderer(self):
return f''
def _generate_meta(self):
meta_tags = []
has_ie_compat = any(
x.get("http-equiv", "") == "X-UA-Compatible" for x in self.config.meta_tags
)
has_charset = any("charset" in x for x in self.config.meta_tags)
has_viewport = any(x.get("name") == "viewport" for x in self.config.meta_tags)
if not has_ie_compat:
meta_tags.append({"http-equiv": "X-UA-Compatible", "content": "IE=edge"})
if not has_charset:
meta_tags.append({"charset": "UTF-8"})
if not has_viewport:
meta_tags.append(
{"name": "viewport", "content": "width=device-width, initial-scale=1"}
)
return meta_tags + self.config.meta_tags
# Serve the JS bundles for each package
def serve_component_suites(self, package_name, fingerprinted_path):
path_in_pkg, has_fingerprint = check_fingerprint(fingerprinted_path)
_validate.validate_js_path(self.registered_paths, package_name, path_in_pkg)
extension = "." + path_in_pkg.split(".")[-1]
mimetype = mimetypes.types_map.get(extension, "application/octet-stream")
package = sys.modules[package_name]
self.logger.debug(
"serving -- package: %s[%s] resource: %s => location: %s",
package_name,
package.__version__,
path_in_pkg,
package.__path__,
)
response = flask.Response(
pkgutil.get_data(package_name, path_in_pkg), mimetype=mimetype
)
if has_fingerprint:
# Fingerprinted resources are good forever (1 year)
# No need for ETag as the fingerprint changes with each build
response.cache_control.max_age = 31536000 # 1 year
else:
# Non-fingerprinted resources are given an ETag that
# will be used / check on future requests
response.add_etag()
tag = response.get_etag()[0]
request_etag = flask.request.headers.get("If-None-Match")
if f'"{tag}"' == request_etag:
response = flask.Response(None, status=304)
return response
def index(self, *args, **kwargs): # pylint: disable=unused-argument
scripts = self._generate_scripts_html()
css = self._generate_css_dist_html()
config = self._generate_config_html()
metas = self._generate_meta()
renderer = self._generate_renderer()
# use self.title instead of app.config.title for backwards compatibility
title = self.title
if self.use_pages and self.config.include_pages_meta:
metas = _page_meta_tags(self) + metas
if self._favicon:
favicon_mod_time = os.path.getmtime(
os.path.join(self.config.assets_folder, self._favicon)
)
favicon_url = f"{self.get_asset_url(self._favicon)}?m={favicon_mod_time}"
else:
prefix = self.config.requests_pathname_prefix
favicon_url = f"{prefix}_favicon.ico?v={__version__}"
favicon = format_tag(
"link",
{"rel": "icon", "type": "image/x-icon", "href": favicon_url},
opened=True,
)
tags = "\n ".join(
format_tag("meta", x, opened=True, sanitize=True) for x in metas
)
index = self.interpolate_index(
metas=tags,
title=title,
css=css,
config=config,
scripts=scripts,
app_entry=_app_entry,
favicon=favicon,
renderer=renderer,
)
checks = (
_re_index_entry_id,
_re_index_config_id,
_re_index_scripts_id,
_re_renderer_scripts_id,
)
_validate.validate_index("index", checks, index)
return index
def interpolate_index(
self,
metas="",
title="",
css="",
config="",
scripts="",
app_entry="",
favicon="",
renderer="",
):
"""Called to create the initial HTML string that is loaded on page.
Override this method to provide you own custom HTML.
:Example:
class MyDash(dash.Dash):
def interpolate_index(self, **kwargs):
return '''
My App
My custom header
{app_entry}
{config}
{scripts}
{renderer}
'''.format(app_entry=kwargs.get('app_entry'),
config=kwargs.get('config'),
scripts=kwargs.get('scripts'),
renderer=kwargs.get('renderer'))
:param metas: Collected & formatted meta tags.
:param title: The title of the app.
:param css: Collected & formatted css dependencies as tags.
:param config: Configs needed by dash-renderer.
:param scripts: Collected & formatted scripts tags.
:param renderer: A script tag that instantiates the DashRenderer.
:param app_entry: Where the app will render.
:param favicon: A favicon tag if found in assets folder.
:return: The interpolated HTML string for the index.
"""
return interpolate_str(
self.index_string,
metas=metas,
title=title,
css=css,
config=config,
scripts=scripts,
favicon=favicon,
renderer=renderer,
app_entry=app_entry,
)
def dependencies(self):
return flask.jsonify(self._callback_list)
def clientside_callback(self, clientside_function, *args, **kwargs):
"""Create a callback that updates the output by calling a clientside
(JavaScript) function instead of a Python function.
Unlike `@app.callback`, `clientside_callback` is not a decorator:
it takes either a
`dash.dependencies.ClientsideFunction(namespace, function_name)`
argument that describes which JavaScript function to call
(Dash will look for the JavaScript function at
`window.dash_clientside[namespace][function_name]`), or it may take
a string argument that contains the clientside function source.
For example, when using a `dash.dependencies.ClientsideFunction`:
```
app.clientside_callback(
ClientsideFunction('my_clientside_library', 'my_function'),
Output('my-div' 'children'),
[Input('my-input', 'value'),
Input('another-input', 'value')]
)
```
With this signature, Dash's front-end will call
`window.dash_clientside.my_clientside_library.my_function` with the
current values of the `value` properties of the components `my-input`
and `another-input` whenever those values change.
Include a JavaScript file by including it your `assets/` folder. The
file can be named anything but you'll need to assign the function's
namespace to the `window.dash_clientside` namespace. For example,
this file might look:
```
window.dash_clientside = window.dash_clientside || {};
window.dash_clientside.my_clientside_library = {
my_function: function(input_value_1, input_value_2) {
return (
parseFloat(input_value_1, 10) +
parseFloat(input_value_2, 10)
);
}
}
```
Alternatively, you can pass the JavaScript source directly to
`clientside_callback`. In this case, the same example would look like:
```
app.clientside_callback(
'''
function(input_value_1, input_value_2) {
return (
parseFloat(input_value_1, 10) +
parseFloat(input_value_2, 10)
);
}
''',
Output('my-div' 'children'),
[Input('my-input', 'value'),
Input('another-input', 'value')]
)
```
The last, optional argument `prevent_initial_call` causes the callback
not to fire when its outputs are first added to the page. Defaults to
`False` unless `prevent_initial_callbacks=True` at the app level.
"""
return _callback.register_clientside_callback(
self._callback_list,
self.callback_map,
self.config.prevent_initial_callbacks,
self._inline_scripts,
clientside_function,
*args,
**kwargs,
)
def callback(self, *_args, **_kwargs):
"""
Normally used as a decorator, `@app.callback` provides a server-side
callback relating the values of one or more `Output` items to one or
more `Input` items which will trigger the callback when they change,
and optionally `State` items which provide additional information but
do not trigger the callback directly.
The last, optional argument `prevent_initial_call` causes the callback
not to fire when its outputs are first added to the page. Defaults to
`False` unless `prevent_initial_callbacks=True` at the app level.
"""
return _callback.callback(
*_args,
config_prevent_initial_callbacks=self.config.prevent_initial_callbacks,
callback_list=self._callback_list,
callback_map=self.callback_map,
**_kwargs,
)
def long_callback(
self,
*_args,
manager=None,
interval=1000,
running=None,
cancel=None,
progress=None,
progress_default=None,
cache_args_to_ignore=None,
**_kwargs,
):
"""
Deprecated: long callbacks are now supported natively with regular callbacks,
use `background=True` with `dash.callback` or `app.callback` instead.
"""
return _callback.callback(
*_args,
background=True,
manager=manager,
interval=interval,
progress=progress,
progress_default=progress_default,
running=running,
cancel=cancel,
cache_args_to_ignore=cache_args_to_ignore,
callback_map=self.callback_map,
callback_list=self._callback_list,
config_prevent_initial_callbacks=self.config.prevent_initial_callbacks,
**_kwargs,
)
def dispatch(self):
body = flask.request.get_json()
g = AttributeDict({})
g.inputs_list = inputs = body.get( # pylint: disable=assigning-non-slot
"inputs", []
)
g.states_list = state = body.get( # pylint: disable=assigning-non-slot
"state", []
)
output = body["output"]
outputs_list = body.get("outputs") or split_callback_id(output)
g.outputs_list = outputs_list # pylint: disable=assigning-non-slot
g.input_values = ( # pylint: disable=assigning-non-slot
input_values
) = inputs_to_dict(inputs)
g.state_values = inputs_to_dict(state) # pylint: disable=assigning-non-slot
changed_props = body.get("changedPropIds", [])
g.triggered_inputs = [ # pylint: disable=assigning-non-slot
{"prop_id": x, "value": input_values.get(x)} for x in changed_props
]
response = (
g.dash_response # pylint: disable=assigning-non-slot
) = flask.Response(mimetype="application/json")
args = inputs_to_vals(inputs + state)
try:
cb = self.callback_map[output]
func = cb["callback"]
g.background_callback_manager = (
cb.get("manager") or self._background_manager
)
g.ignore_register_page = cb.get("long", False)
# Add args_grouping
inputs_state_indices = cb["inputs_state_indices"]
inputs_state = inputs + state
inputs_state = convert_to_AttributeDict(inputs_state)
# update args_grouping attributes
for s in inputs_state:
# check for pattern matching: list of inputs or state
if isinstance(s, list):
for pattern_match_g in s:
update_args_group(pattern_match_g, changed_props)
update_args_group(s, changed_props)
args_grouping = map_grouping(
lambda ind: inputs_state[ind], inputs_state_indices
)
g.args_grouping = args_grouping # pylint: disable=assigning-non-slot
g.using_args_grouping = ( # pylint: disable=assigning-non-slot
not isinstance(inputs_state_indices, int)
and (
inputs_state_indices
!= list(range(grouping_len(inputs_state_indices)))
)
)
# Add outputs_grouping
outputs_indices = cb["outputs_indices"]
if not isinstance(outputs_list, list):
flat_outputs = [outputs_list]
else:
flat_outputs = outputs_list
outputs_grouping = map_grouping(
lambda ind: flat_outputs[ind], outputs_indices
)
g.outputs_grouping = outputs_grouping # pylint: disable=assigning-non-slot
g.using_outputs_grouping = ( # pylint: disable=assigning-non-slot
not isinstance(outputs_indices, int)
and outputs_indices != list(range(grouping_len(outputs_indices)))
)
except KeyError as missing_callback_function:
msg = f"Callback function not found for output '{output}', perhaps you forgot to prepend the '@'?"
raise KeyError(msg) from missing_callback_function
ctx = copy_context()
# noinspection PyArgumentList
response.set_data(
ctx.run(
functools.partial(
func,
*args,
outputs_list=outputs_list,
long_callback_manager=self._background_manager,
callback_context=g,
)
)
)
return response
def _setup_server(self):
if self._got_first_request["setup_server"]:
return
self._got_first_request["setup_server"] = True
# Apply _force_eager_loading overrides from modules
eager_loading = self.config.eager_loading
for module_name in ComponentRegistry.registry:
module = sys.modules[module_name]
eager = getattr(module, "_force_eager_loading", False)
eager_loading = eager_loading or eager
# Update eager_loading settings
self.scripts.config.eager_loading = eager_loading
if self.config.include_assets_files:
self._walk_assets_directory()
if not self.layout and self.use_pages:
self.layout = page_container
_validate.validate_layout(self.layout, self._layout_value())
self._generate_scripts_html()
self._generate_css_dist_html()
# Copy over global callback data structures assigned with `dash.callback`
for k in list(_callback.GLOBAL_CALLBACK_MAP):
if k in self.callback_map:
raise DuplicateCallback(
f"The callback `{k}` provided with `dash.callback` was already "
"assigned with `app.callback`."
)
self.callback_map[k] = _callback.GLOBAL_CALLBACK_MAP.pop(k)
self._callback_list.extend(_callback.GLOBAL_CALLBACK_LIST)
_callback.GLOBAL_CALLBACK_LIST.clear()
_validate.validate_long_callbacks(self.callback_map)
cancels = {}
for callback in self.callback_map.values():
long = callback.get("long")
if not long:
continue
if "cancel_inputs" in long:
cancel = long.pop("cancel_inputs")
for c in cancel:
cancels[c] = long.get("manager")
if cancels:
for cancel_input, manager in cancels.items():
# pylint: disable=cell-var-from-loop
@self.callback(
Output(cancel_input.component_id, "id"),
cancel_input,
prevent_initial_call=True,
manager=manager,
)
def cancel_call(*_):
job_ids = flask.request.args.getlist("cancelJob")
executor = _callback.context_value.get().background_callback_manager
if job_ids:
for job_id in job_ids:
executor.terminate_job(job_id)
return no_update
def _add_assets_resource(self, url_path, file_path):
res = {"asset_path": url_path, "filepath": file_path}
if self.config.assets_external_path:
res["external_url"] = self.get_asset_url(url_path.lstrip("/"))
self._assets_files.append(file_path)
return res
def _walk_assets_directory(self):
walk_dir = self.config.assets_folder
slash_splitter = re.compile(r"[\\/]+")
ignore_str = self.config.assets_ignore
ignore_filter = re.compile(ignore_str) if ignore_str else None
for current, _, files in sorted(os.walk(walk_dir)):
if current == walk_dir:
base = ""
else:
s = current.replace(walk_dir, "").lstrip("\\").lstrip("/")
splitted = slash_splitter.split(s)
if len(splitted) > 1:
base = "/".join(slash_splitter.split(s))
else:
base = splitted[0]
if ignore_filter:
files_gen = (x for x in files if not ignore_filter.search(x))
else:
files_gen = files
for f in sorted(files_gen):
path = "/".join([base, f]) if base else f
full = os.path.join(current, f)
if f.endswith("js"):
self.scripts.append_script(self._add_assets_resource(path, full))
elif f.endswith("css"):
self.css.append_css(self._add_assets_resource(path, full))
elif f == "favicon.ico":
self._favicon = path
@staticmethod
def _invalid_resources_handler(err):
return err.args[0], 404
@staticmethod
def _serve_default_favicon():
return flask.Response(
pkgutil.get_data("dash", "favicon.ico"), content_type="image/x-icon"
)
def csp_hashes(self, hash_algorithm="sha256"):
"""Calculates CSP hashes (sha + base64) of all inline scripts, such that
one of the biggest benefits of CSP (disallowing general inline scripts)
can be utilized together with Dash clientside callbacks (inline scripts).
Calculate these hashes after all inline callbacks are defined,
and add them to your CSP headers before starting the server, for example
with the flask-talisman package from PyPI:
flask_talisman.Talisman(app.server, content_security_policy={
"default-src": "'self'",
"script-src": ["'self'"] + app.csp_hashes()
})
:param hash_algorithm: One of the recognized CSP hash algorithms ('sha256', 'sha384', 'sha512').
:return: List of CSP hash strings of all inline scripts.
"""
HASH_ALGORITHMS = ["sha256", "sha384", "sha512"]
if hash_algorithm not in HASH_ALGORITHMS:
raise ValueError(
"Possible CSP hash algorithms: " + ", ".join(HASH_ALGORITHMS)
)
method = getattr(hashlib, hash_algorithm)
def _hash(script):
return base64.b64encode(method(script.encode("utf-8")).digest()).decode(
"utf-8"
)
self._inline_scripts.extend(_callback.GLOBAL_INLINE_SCRIPTS)
_callback.GLOBAL_INLINE_SCRIPTS.clear()
return [
f"'{hash_algorithm}-{_hash(script)}'"
for script in (self._inline_scripts + [self.renderer])
]
def get_asset_url(self, path):
return _get_paths.app_get_asset_url(self.config, path)
def get_relative_path(self, 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 _get_paths.app_get_relative_path(
self.config.requests_pathname_prefix, path
)
def strip_relative_path(self, 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 _get_paths.app_strip_relative_path(
self.config.requests_pathname_prefix, path
)
def _setup_dev_tools(self, **kwargs):
debug = kwargs.get("debug", False)
dev_tools = self._dev_tools = AttributeDict()
for attr in (
"ui",
"props_check",
"serve_dev_bundles",
"hot_reload",
"silence_routes_logging",
"prune_errors",
):
dev_tools[attr] = get_combined_config(
attr, kwargs.get(attr, None), default=debug
)
for attr, _type, default in (
("hot_reload_interval", float, 3),
("hot_reload_watch_interval", float, 0.5),
("hot_reload_max_retry", int, 8),
):
dev_tools[attr] = _type(
get_combined_config(attr, kwargs.get(attr, None), default=default)
)
return dev_tools
def enable_dev_tools(
self,
debug=None,
dev_tools_ui=None,
dev_tools_props_check=None,
dev_tools_serve_dev_bundles=None,
dev_tools_hot_reload=None,
dev_tools_hot_reload_interval=None,
dev_tools_hot_reload_watch_interval=None,
dev_tools_hot_reload_max_retry=None,
dev_tools_silence_routes_logging=None,
dev_tools_prune_errors=None,
):
"""Activate the dev tools, called by `run`. If your application
is served by wsgi and you want to activate the dev tools, you can call
this method out of `__main__`.
All parameters can be set by environment variables as listed.
Values provided here take precedence over environment variables.
Available dev_tools environment variables:
- DASH_DEBUG
- DASH_UI
- DASH_PROPS_CHECK
- DASH_SERVE_DEV_BUNDLES
- DASH_HOT_RELOAD
- DASH_HOT_RELOAD_INTERVAL
- DASH_HOT_RELOAD_WATCH_INTERVAL
- DASH_HOT_RELOAD_MAX_RETRY
- DASH_SILENCE_ROUTES_LOGGING
- DASH_PRUNE_ERRORS
:param debug: Enable/disable all the dev tools unless overridden by the
arguments or environment variables. Default is ``True`` when
``enable_dev_tools`` is called directly, and ``False`` when called
via ``run``. env: ``DASH_DEBUG``
:type debug: bool
:param dev_tools_ui: Show the dev tools UI. env: ``DASH_UI``
:type dev_tools_ui: bool
:param dev_tools_props_check: Validate the types and values of Dash
component props. env: ``DASH_PROPS_CHECK``
:type dev_tools_props_check: bool
:param dev_tools_serve_dev_bundles: Serve the dev bundles. Production
bundles do not necessarily include all the dev tools code.
env: ``DASH_SERVE_DEV_BUNDLES``
:type dev_tools_serve_dev_bundles: bool
:param dev_tools_hot_reload: Activate hot reloading when app, assets,
and component files change. env: ``DASH_HOT_RELOAD``
:type dev_tools_hot_reload: bool
:param dev_tools_hot_reload_interval: Interval in seconds for the
client to request the reload hash. Default 3.
env: ``DASH_HOT_RELOAD_INTERVAL``
:type dev_tools_hot_reload_interval: float
:param dev_tools_hot_reload_watch_interval: Interval in seconds for the
server to check asset and component folders for changes.
Default 0.5. env: ``DASH_HOT_RELOAD_WATCH_INTERVAL``
:type dev_tools_hot_reload_watch_interval: float
:param dev_tools_hot_reload_max_retry: Maximum number of failed reload
hash requests before failing and displaying a pop up. Default 8.
env: ``DASH_HOT_RELOAD_MAX_RETRY``
:type dev_tools_hot_reload_max_retry: int
:param dev_tools_silence_routes_logging: Silence the `werkzeug` logger,
will remove all routes logging. Enabled with debugging by default
because hot reload hash checks generate a lot of requests.
env: ``DASH_SILENCE_ROUTES_LOGGING``
:type dev_tools_silence_routes_logging: bool
:param dev_tools_prune_errors: Reduce tracebacks to just user code,
stripping out Flask and Dash pieces. Only available with debugging.
`True` by default, set to `False` to see the complete traceback.
env: ``DASH_PRUNE_ERRORS``
:type dev_tools_prune_errors: bool
:return: debug
"""
if debug is None:
debug = get_combined_config("debug", None, True)
dev_tools = self._setup_dev_tools(
debug=debug,
ui=dev_tools_ui,
props_check=dev_tools_props_check,
serve_dev_bundles=dev_tools_serve_dev_bundles,
hot_reload=dev_tools_hot_reload,
hot_reload_interval=dev_tools_hot_reload_interval,
hot_reload_watch_interval=dev_tools_hot_reload_watch_interval,
hot_reload_max_retry=dev_tools_hot_reload_max_retry,
silence_routes_logging=dev_tools_silence_routes_logging,
prune_errors=dev_tools_prune_errors,
)
if dev_tools.silence_routes_logging:
logging.getLogger("werkzeug").setLevel(logging.ERROR)
if dev_tools.hot_reload:
_reload = self._hot_reload
_reload.hash = generate_hash()
# find_loader should return None on __main__ but doesn't
# on some Python versions https://bugs.python.org/issue14710
packages = [
pkgutil.find_loader(x)
for x in list(ComponentRegistry.registry)
if x != "__main__"
]
# # additional condition to account for AssertionRewritingHook object
# # loader when running pytest
if "_pytest" in sys.modules:
from _pytest.assertion.rewrite import ( # pylint: disable=import-outside-toplevel
AssertionRewritingHook,
)
for index, package in enumerate(packages):
if isinstance(package, AssertionRewritingHook):
dash_spec = importlib.util.find_spec("dash")
dash_test_path = dash_spec.submodule_search_locations[0]
setattr(dash_spec, "path", dash_test_path)
packages[index] = dash_spec
component_packages_dist = [
dash_test_path
if isinstance(package, ModuleSpec)
else os.path.dirname(package.path)
if hasattr(package, "path")
else os.path.dirname(
package._path[0] # pylint: disable=protected-access
)
if hasattr(package, "_path")
else package.filename
for package in packages
]
for i, package in enumerate(packages):
if hasattr(package, "path") and "dash/dash" in os.path.dirname(
package.path
):
component_packages_dist[i : i + 1] = [
os.path.join(os.path.dirname(package.path), x)
for x in ["dcc", "html", "dash_table"]
]
_reload.watch_thread = threading.Thread(
target=lambda: _watch.watch(
[self.config.assets_folder] + component_packages_dist,
self._on_assets_change,
sleep_time=dev_tools.hot_reload_watch_interval,
)
)
_reload.watch_thread.daemon = True
_reload.watch_thread.start()
if debug:
if jupyter_dash.active:
jupyter_dash.configure_callback_exception_handling(
self, dev_tools.prune_errors
)
elif dev_tools.prune_errors:
secret = gen_salt(20)
@self.server.errorhandler(Exception)
def _wrap_errors(error):
# find the callback invocation, if the error is from a callback
# and skip the traceback up to that point
# if the error didn't come from inside a callback, we won't
# skip anything.
tb = _get_traceback(secret, error)
return tb, 500
if debug and dev_tools.ui:
def _before_request():
flask.g.timing_information = { # pylint: disable=assigning-non-slot
"__dash_server": {"dur": time.time(), "desc": None}
}
def _after_request(response):
timing_information = flask.g.get("timing_information", None)
if timing_information is None:
return response
dash_total = timing_information.get("__dash_server", None)
if dash_total is not None:
dash_total["dur"] = round((time.time() - dash_total["dur"]) * 1000)
for name, info in timing_information.items():
value = name
if info.get("desc") is not None:
value += f';desc="{info["desc"]}"'
if info.get("dur") is not None:
value += f";dur={info['dur']}"
response.headers.add("Server-Timing", value)
return response
self.server.before_request(_before_request)
self.server.after_request(_after_request)
if (
debug
and dev_tools.serve_dev_bundles
and not self.scripts.config.serve_locally
):
# Dev bundles only works locally.
self.scripts.config.serve_locally = True
print(
"WARNING: dev bundles requested with serve_locally=False.\n"
"This is not supported, switching to serve_locally=True"
)
return debug
# noinspection PyProtectedMember
def _on_assets_change(self, filename, modified, deleted):
_reload = self._hot_reload
with _reload.lock:
_reload.hard = True
_reload.hash = generate_hash()
if self.config.assets_folder in filename:
asset_path = (
os.path.relpath(
filename,
os.path.commonprefix([self.config.assets_folder, filename]),
)
.replace("\\", "/")
.lstrip("/")
)
_reload.changed_assets.append(
{
"url": self.get_asset_url(asset_path),
"modified": int(modified),
"is_css": filename.endswith("css"),
}
)
if filename not in self._assets_files and not deleted:
res = self._add_assets_resource(asset_path, filename)
if filename.endswith("js"):
self.scripts.append_script(res)
elif filename.endswith("css"):
self.css.append_css(res)
if deleted:
if filename in self._assets_files:
self._assets_files.remove(filename)
def delete_resource(resources):
to_delete = None
for r in resources:
if r.get("asset_path") == asset_path:
to_delete = r
break
if to_delete:
resources.remove(to_delete)
if filename.endswith("js"):
# pylint: disable=protected-access
delete_resource(self.scripts._resources._resources)
elif filename.endswith("css"):
# pylint: disable=protected-access
delete_resource(self.css._resources._resources)
def run(
self,
host=os.getenv("HOST", "127.0.0.1"),
port=os.getenv("PORT", "8050"),
proxy=os.getenv("DASH_PROXY", None),
debug=None,
jupyter_mode: JupyterDisplayMode = None,
jupyter_width="100%",
jupyter_height=650,
jupyter_server_url=None,
dev_tools_ui=None,
dev_tools_props_check=None,
dev_tools_serve_dev_bundles=None,
dev_tools_hot_reload=None,
dev_tools_hot_reload_interval=None,
dev_tools_hot_reload_watch_interval=None,
dev_tools_hot_reload_max_retry=None,
dev_tools_silence_routes_logging=None,
dev_tools_prune_errors=None,
**flask_run_options,
):
"""Start the flask server in local mode, you should not run this on a
production server, use gunicorn/waitress instead.
If a parameter can be set by an environment variable, that is listed
too. Values provided here take precedence over environment variables.
:param host: Host IP used to serve the application
env: ``HOST``
:type host: string
:param port: Port used to serve the application
env: ``PORT``
:type port: int
:param proxy: If this application will be served to a different URL
via a proxy configured outside of Python, you can list it here
as a string of the form ``"{input}::{output}"``, for example:
``"http://0.0.0.0:8050::https://my.domain.com"``
so that the startup message will display an accurate URL.
env: ``DASH_PROXY``
:type proxy: string
:param debug: Set Flask debug mode and enable dev tools.
env: ``DASH_DEBUG``
:type debug: bool
:param debug: Enable/disable all the dev tools unless overridden by the
arguments or environment variables. Default is ``True`` when
``enable_dev_tools`` is called directly, and ``False`` when called
via ``run``. env: ``DASH_DEBUG``
:type debug: bool
:param dev_tools_ui: Show the dev tools UI. env: ``DASH_UI``
:type dev_tools_ui: bool
:param dev_tools_props_check: Validate the types and values of Dash
component props. env: ``DASH_PROPS_CHECK``
:type dev_tools_props_check: bool
:param dev_tools_serve_dev_bundles: Serve the dev bundles. Production
bundles do not necessarily include all the dev tools code.
env: ``DASH_SERVE_DEV_BUNDLES``
:type dev_tools_serve_dev_bundles: bool
:param dev_tools_hot_reload: Activate hot reloading when app, assets,
and component files change. env: ``DASH_HOT_RELOAD``
:type dev_tools_hot_reload: bool
:param dev_tools_hot_reload_interval: Interval in seconds for the
client to request the reload hash. Default 3.
env: ``DASH_HOT_RELOAD_INTERVAL``
:type dev_tools_hot_reload_interval: float
:param dev_tools_hot_reload_watch_interval: Interval in seconds for the
server to check asset and component folders for changes.
Default 0.5. env: ``DASH_HOT_RELOAD_WATCH_INTERVAL``
:type dev_tools_hot_reload_watch_interval: float
:param dev_tools_hot_reload_max_retry: Maximum number of failed reload
hash requests before failing and displaying a pop up. Default 8.
env: ``DASH_HOT_RELOAD_MAX_RETRY``
:type dev_tools_hot_reload_max_retry: int
:param dev_tools_silence_routes_logging: Silence the `werkzeug` logger,
will remove all routes logging. Enabled with debugging by default
because hot reload hash checks generate a lot of requests.
env: ``DASH_SILENCE_ROUTES_LOGGING``
:type dev_tools_silence_routes_logging: bool
:param dev_tools_prune_errors: Reduce tracebacks to just user code,
stripping out Flask and Dash pieces. Only available with debugging.
`True` by default, set to `False` to see the complete traceback.
env: ``DASH_PRUNE_ERRORS``
:type dev_tools_prune_errors: bool
:param jupyter_mode: How to display the application when running
inside a jupyter notebook.
:param jupyter_width: Determine the width of the output cell
when displaying inline in jupyter notebooks.
:type jupyter_width: str
:param jupyter_height: Height of app when displayed using
jupyter_mode="inline"
:type jupyter_height: int
:param jupyter_server_url: Custom server url to display
the app in jupyter notebook.
:param flask_run_options: Given to `Flask.run`
:return:
"""
if debug is None:
debug = get_combined_config("debug", None, False)
debug = self.enable_dev_tools(
debug,
dev_tools_ui,
dev_tools_props_check,
dev_tools_serve_dev_bundles,
dev_tools_hot_reload,
dev_tools_hot_reload_interval,
dev_tools_hot_reload_watch_interval,
dev_tools_hot_reload_max_retry,
dev_tools_silence_routes_logging,
dev_tools_prune_errors,
)
# Verify port value
try:
port = int(port)
assert port in range(1, 65536)
except Exception as e:
e.args = [f"Expecting an integer from 1 to 65535, found port={repr(port)}"]
raise
# so we only see the "Running on" message once with hot reloading
# https://stackoverflow.com/a/57231282/9188800
if os.getenv("WERKZEUG_RUN_MAIN") != "true":
ssl_context = flask_run_options.get("ssl_context")
protocol = "https" if ssl_context else "http"
path = self.config.requests_pathname_prefix
if proxy:
served_url, proxied_url = map(urlparse, proxy.split("::"))
def verify_url_part(served_part, url_part, part_name):
if served_part != url_part:
raise ProxyError(
f"""
{part_name}: {url_part} is incompatible with the proxy:
{proxy}
To see your app at {proxied_url.geturl()},
you must use {part_name}: {served_part}
"""
)
verify_url_part(served_url.scheme, protocol, "protocol")
verify_url_part(served_url.hostname, host, "host")
verify_url_part(served_url.port, port, "port")
display_url = (
proxied_url.scheme,
proxied_url.hostname,
f":{proxied_url.port}" if proxied_url.port else "",
path,
)
else:
display_url = (protocol, host, f":{port}", path)
if not jupyter_dash or not jupyter_dash.in_ipython:
self.logger.info("Dash is running on %s://%s%s%s\n", *display_url)
if self.config.extra_hot_reload_paths:
extra_files = flask_run_options["extra_files"] = []
for path in self.config.extra_hot_reload_paths:
if os.path.isdir(path):
for dirpath, _, filenames in os.walk(path):
for fn in filenames:
extra_files.append(os.path.join(dirpath, fn))
elif os.path.isfile(path):
extra_files.append(path)
if jupyter_dash.active:
jupyter_dash.run_app(
self,
mode=jupyter_mode,
width=jupyter_width,
height=jupyter_height,
host=host,
port=port,
server_url=jupyter_server_url,
)
else:
self.server.run(host=host, port=port, debug=debug, **flask_run_options)
def enable_pages(self):
if not self.use_pages:
return
if self.pages_folder:
_import_layouts_from_pages(self.config.pages_folder)
@self.server.before_request
def router():
if self._got_first_request["pages"]:
return
self._got_first_request["pages"] = True
inputs = {
"pathname_": Input(_ID_LOCATION, "pathname"),
"search_": Input(_ID_LOCATION, "search"),
}
inputs.update(self.routing_callback_inputs)
@self.callback(
Output(_ID_CONTENT, "children"),
Output(_ID_STORE, "data"),
inputs=inputs,
prevent_initial_call=True,
)
def update(pathname_, search_, **states):
"""
Updates dash.page_container layout on page navigation.
Updates the stored page title which will trigger the clientside callback to update the app title
"""
query_parameters = _parse_query_string(search_)
page, path_variables = _path_to_page(
self.strip_relative_path(pathname_)
)
# get layout
if page == {}:
for module, page in _pages.PAGE_REGISTRY.items():
if module.split(".")[-1] == "not_found_404":
layout = page["layout"]
title = page["title"]
break
else:
layout = html.H1("404 - Page not found")
title = self.title
else:
layout = page.get("layout", "")
title = page["title"]
if callable(layout):
layout = (
layout(**path_variables, **query_parameters, **states)
if path_variables
else layout(**query_parameters, **states)
)
if callable(title):
title = title(**path_variables) if path_variables else title()
return layout, {"title": title}
_validate.check_for_duplicate_pathnames(_pages.PAGE_REGISTRY)
_validate.validate_registry(_pages.PAGE_REGISTRY)
# Set validation_layout
if not self.config.suppress_callback_exceptions:
self.validation_layout = html.Div(
[
page["layout"]() if callable(page["layout"]) else page["layout"]
for page in _pages.PAGE_REGISTRY.values()
]
+ [
# pylint: disable=not-callable
self.layout()
if callable(self.layout)
else self.layout
]
)
if _ID_CONTENT not in self.validation_layout:
raise Exception("`dash.page_container` not found in the layout")
# Update the page title on page navigation
self.clientside_callback(
"""
function(data) {{
document.title = data.title
}}
""",
Output(_ID_DUMMY, "children"),
Input(_ID_STORE, "data"),
)
def run_server(self, *args, **kwargs):
"""`run_server` is a deprecated alias of `run` and may be removed in a
future version. We recommend using `app.run` instead.
See `app.run` for usage information.
"""
self.run(*args, **kwargs)