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import os
import typing as t
from collections import defaultdict
from functools import update_wrapper
from .scaffold import _endpoint_from_view_func
from .scaffold import _sentinel
from .scaffold import Scaffold
from .typing import AfterRequestCallable
from .typing import BeforeFirstRequestCallable
from .typing import BeforeRequestCallable
from .typing import TeardownCallable
from .typing import TemplateContextProcessorCallable
from .typing import TemplateFilterCallable
from .typing import TemplateGlobalCallable
from .typing import TemplateTestCallable
from .typing import URLDefaultCallable
from .typing import URLValuePreprocessorCallable
if t.TYPE_CHECKING:
from .app import Flask
from .typing import ErrorHandlerCallable
DeferredSetupFunction = t.Callable[["BlueprintSetupState"], t.Callable]
class BlueprintSetupState:
"""Temporary holder object for registering a blueprint with the
application. An instance of this class is created by the
:meth:`~flask.Blueprint.make_setup_state` method and later passed
to all register callback functions.
"""
def __init__(
self,
blueprint: "Blueprint",
app: "Flask",
options: t.Any,
first_registration: bool,
) -> None:
#: a reference to the current application
self.app = app
#: a reference to the blueprint that created this setup state.
self.blueprint = blueprint
#: a dictionary with all options that were passed to the
#: :meth:`~flask.Flask.register_blueprint` method.
self.options = options
#: as blueprints can be registered multiple times with the
#: application and not everything wants to be registered
#: multiple times on it, this attribute can be used to figure
#: out if the blueprint was registered in the past already.
self.first_registration = first_registration
subdomain = self.options.get("subdomain")
if subdomain is None:
subdomain = self.blueprint.subdomain
#: The subdomain that the blueprint should be active for, ``None``
#: otherwise.
self.subdomain = subdomain
url_prefix = self.options.get("url_prefix")
if url_prefix is None:
url_prefix = self.blueprint.url_prefix
#: The prefix that should be used for all URLs defined on the
#: blueprint.
self.url_prefix = url_prefix
self.name = self.options.get("name", blueprint.name)
self.name_prefix = self.options.get("name_prefix", "")
#: A dictionary with URL defaults that is added to each and every
#: URL that was defined with the blueprint.
self.url_defaults = dict(self.blueprint.url_values_defaults)
self.url_defaults.update(self.options.get("url_defaults", ()))
def add_url_rule(
self,
rule: str,
endpoint: t.Optional[str] = None,
view_func: t.Optional[t.Callable] = None,
**options: t.Any,
) -> None:
"""A helper method to register a rule (and optionally a view function)
to the application. The endpoint is automatically prefixed with the
blueprint's name.
"""
if self.url_prefix is not None:
if rule:
rule = "/".join((self.url_prefix.rstrip("/"), rule.lstrip("/")))
else:
rule = self.url_prefix
options.setdefault("subdomain", self.subdomain)
if endpoint is None:
endpoint = _endpoint_from_view_func(view_func) # type: ignore
defaults = self.url_defaults
if "defaults" in options:
defaults = dict(defaults, **options.pop("defaults"))
self.app.add_url_rule(
rule,
f"{self.name_prefix}.{self.name}.{endpoint}".lstrip("."),
view_func,
defaults=defaults,
**options,
)
class Blueprint(Scaffold):
"""Represents a blueprint, a collection of routes and other
app-related functions that can be registered on a real application
later.
A blueprint is an object that allows defining application functions
without requiring an application object ahead of time. It uses the
same decorators as :class:`~flask.Flask`, but defers the need for an
application by recording them for later registration.
Decorating a function with a blueprint creates a deferred function
that is called with :class:`~flask.blueprints.BlueprintSetupState`
when the blueprint is registered on an application.
See :doc:`/blueprints` for more information.
:param name: The name of the blueprint. Will be prepended to each
endpoint name.
:param import_name: The name of the blueprint package, usually
``__name__``. This helps locate the ``root_path`` for the
blueprint.
:param static_folder: A folder with static files that should be
served by the blueprint's static route. The path is relative to
the blueprint's root path. Blueprint static files are disabled
by default.
:param static_url_path: The url to serve static files from.
Defaults to ``static_folder``. If the blueprint does not have
a ``url_prefix``, the app's static route will take precedence,
and the blueprint's static files won't be accessible.
:param template_folder: A folder with templates that should be added
to the app's template search path. The path is relative to the
blueprint's root path. Blueprint templates are disabled by
default. Blueprint templates have a lower precedence than those
in the app's templates folder.
:param url_prefix: A path to prepend to all of the blueprint's URLs,
to make them distinct from the rest of the app's routes.
:param subdomain: A subdomain that blueprint routes will match on by
default.
:param url_defaults: A dict of default values that blueprint routes
will receive by default.
:param root_path: By default, the blueprint will automatically set
this based on ``import_name``. In certain situations this
automatic detection can fail, so the path can be specified
manually instead.
.. versionchanged:: 1.1.0
Blueprints have a ``cli`` group to register nested CLI commands.
The ``cli_group`` parameter controls the name of the group under
the ``flask`` command.
.. versionadded:: 0.7
"""
warn_on_modifications = False
_got_registered_once = False
#: Blueprint local JSON encoder class to use. Set to ``None`` to use
#: the app's :class:`~flask.Flask.json_encoder`.
json_encoder = None
#: Blueprint local JSON decoder class to use. Set to ``None`` to use
#: the app's :class:`~flask.Flask.json_decoder`.
json_decoder = None
def __init__(
self,
name: str,
import_name: str,
static_folder: t.Optional[t.Union[str, os.PathLike]] = None,
static_url_path: t.Optional[str] = None,
template_folder: t.Optional[str] = None,
url_prefix: t.Optional[str] = None,
subdomain: t.Optional[str] = None,
url_defaults: t.Optional[dict] = None,
root_path: t.Optional[str] = None,
cli_group: t.Optional[str] = _sentinel, # type: ignore
):
super().__init__(
import_name=import_name,
static_folder=static_folder,
static_url_path=static_url_path,
template_folder=template_folder,
root_path=root_path,
)
if "." in name:
raise ValueError("'name' may not contain a dot '.' character.")
self.name = name
self.url_prefix = url_prefix
self.subdomain = subdomain
self.deferred_functions: t.List[DeferredSetupFunction] = []
if url_defaults is None:
url_defaults = {}
self.url_values_defaults = url_defaults
self.cli_group = cli_group
self._blueprints: t.List[t.Tuple["Blueprint", dict]] = []
def _is_setup_finished(self) -> bool:
return self.warn_on_modifications and self._got_registered_once
def record(self, func: t.Callable) -> None:
"""Registers a function that is called when the blueprint is
registered on the application. This function is called with the
state as argument as returned by the :meth:`make_setup_state`
method.
"""
if self._got_registered_once and self.warn_on_modifications:
from warnings import warn
warn(
Warning(
"The blueprint was already registered once but is"
" getting modified now. These changes will not show"
" up."
)
)
self.deferred_functions.append(func)
def record_once(self, func: t.Callable) -> None:
"""Works like :meth:`record` but wraps the function in another
function that will ensure the function is only called once. If the
blueprint is registered a second time on the application, the
function passed is not called.
"""
def wrapper(state: BlueprintSetupState) -> None:
if state.first_registration:
func(state)
return self.record(update_wrapper(wrapper, func))
def make_setup_state(
self, app: "Flask", options: dict, first_registration: bool = False
) -> BlueprintSetupState:
"""Creates an instance of :meth:`~flask.blueprints.BlueprintSetupState`
object that is later passed to the register callback functions.
Subclasses can override this to return a subclass of the setup state.
"""
return BlueprintSetupState(self, app, options, first_registration)
def register_blueprint(self, blueprint: "Blueprint", **options: t.Any) -> None:
"""Register a :class:`~flask.Blueprint` on this blueprint. Keyword
arguments passed to this method will override the defaults set
on the blueprint.
.. versionchanged:: 2.0.1
The ``name`` option can be used to change the (pre-dotted)
name the blueprint is registered with. This allows the same
blueprint to be registered multiple times with unique names
for ``url_for``.
.. versionadded:: 2.0
"""
if blueprint is self:
raise ValueError("Cannot register a blueprint on itself")
self._blueprints.append((blueprint, options))
def register(self, app: "Flask", options: dict) -> None:
"""Called by :meth:`Flask.register_blueprint` to register all
views and callbacks registered on the blueprint with the
application. Creates a :class:`.BlueprintSetupState` and calls
each :meth:`record` callback with it.
:param app: The application this blueprint is being registered
with.
:param options: Keyword arguments forwarded from
:meth:`~Flask.register_blueprint`.
.. versionchanged:: 2.0.1
Nested blueprints are registered with their dotted name.
This allows different blueprints with the same name to be
nested at different locations.
.. versionchanged:: 2.0.1
The ``name`` option can be used to change the (pre-dotted)
name the blueprint is registered with. This allows the same
blueprint to be registered multiple times with unique names
for ``url_for``.
.. versionchanged:: 2.0.1
Registering the same blueprint with the same name multiple
times is deprecated and will become an error in Flask 2.1.
"""
name_prefix = options.get("name_prefix", "")
self_name = options.get("name", self.name)
name = f"{name_prefix}.{self_name}".lstrip(".")
if name in app.blueprints:
existing_at = f" '{name}'" if self_name != name else ""
if app.blueprints[name] is not self:
raise ValueError(
f"The name '{self_name}' is already registered for"
f" a different blueprint{existing_at}. Use 'name='"
" to provide a unique name."
)
else:
import warnings
warnings.warn(
f"The name '{self_name}' is already registered for"
f" this blueprint{existing_at}. Use 'name=' to"
" provide a unique name. This will become an error"
" in Flask 2.1.",
stacklevel=4,
)
first_bp_registration = not any(bp is self for bp in app.blueprints.values())
first_name_registration = name not in app.blueprints
app.blueprints[name] = self
self._got_registered_once = True
state = self.make_setup_state(app, options, first_bp_registration)
if self.has_static_folder:
state.add_url_rule(
f"{self.static_url_path}/<path:filename>",
view_func=self.send_static_file,
endpoint="static",
)
# Merge blueprint data into parent.
if first_bp_registration or first_name_registration:
def extend(bp_dict, parent_dict):
for key, values in bp_dict.items():
key = name if key is None else f"{name}.{key}"
parent_dict[key].extend(values)
for key, value in self.error_handler_spec.items():
key = name if key is None else f"{name}.{key}"
value = defaultdict(
dict,
{
code: {
exc_class: func for exc_class, func in code_values.items()
}
for code, code_values in value.items()
},
)
app.error_handler_spec[key] = value
for endpoint, func in self.view_functions.items():
app.view_functions[endpoint] = func
extend(self.before_request_funcs, app.before_request_funcs)
extend(self.after_request_funcs, app.after_request_funcs)
extend(
self.teardown_request_funcs,
app.teardown_request_funcs,
)
extend(self.url_default_functions, app.url_default_functions)
extend(self.url_value_preprocessors, app.url_value_preprocessors)
extend(self.template_context_processors, app.template_context_processors)
for deferred in self.deferred_functions:
deferred(state)
cli_resolved_group = options.get("cli_group", self.cli_group)
if self.cli.commands:
if cli_resolved_group is None:
app.cli.commands.update(self.cli.commands)
elif cli_resolved_group is _sentinel:
self.cli.name = name
app.cli.add_command(self.cli)
else:
self.cli.name = cli_resolved_group
app.cli.add_command(self.cli)
for blueprint, bp_options in self._blueprints:
bp_options = bp_options.copy()
bp_url_prefix = bp_options.get("url_prefix")
if bp_url_prefix is None:
bp_url_prefix = blueprint.url_prefix
if state.url_prefix is not None and bp_url_prefix is not None:
bp_options["url_prefix"] = (
state.url_prefix.rstrip("/") + "/" + bp_url_prefix.lstrip("/")
)
elif bp_url_prefix is not None:
bp_options["url_prefix"] = bp_url_prefix
elif state.url_prefix is not None:
bp_options["url_prefix"] = state.url_prefix
bp_options["name_prefix"] = name
blueprint.register(app, bp_options)
def add_url_rule(
self,
rule: str,
endpoint: t.Optional[str] = None,
view_func: t.Optional[t.Callable] = None,
provide_automatic_options: t.Optional[bool] = None,
**options: t.Any,
) -> None:
"""Like :meth:`Flask.add_url_rule` but for a blueprint. The endpoint for
the :func:`url_for` function is prefixed with the name of the blueprint.
"""
if endpoint and "." in endpoint:
raise ValueError("'endpoint' may not contain a dot '.' character.")
if view_func and hasattr(view_func, "__name__") and "." in view_func.__name__:
raise ValueError("'view_func' name may not contain a dot '.' character.")
self.record(
lambda s: s.add_url_rule(
rule,
endpoint,
view_func,
provide_automatic_options=provide_automatic_options,
**options,
)
)
def app_template_filter(
self, name: t.Optional[str] = None
) -> t.Callable[[TemplateFilterCallable], TemplateFilterCallable]:
"""Register a custom template filter, available application wide. Like
:meth:`Flask.template_filter` but for a blueprint.
:param name: the optional name of the filter, otherwise the
function name will be used.
"""
def decorator(f: TemplateFilterCallable) -> TemplateFilterCallable:
self.add_app_template_filter(f, name=name)
return f
return decorator
def add_app_template_filter(
self, f: TemplateFilterCallable, name: t.Optional[str] = None
) -> None:
"""Register a custom template filter, available application wide. Like
:meth:`Flask.add_template_filter` but for a blueprint. Works exactly
like the :meth:`app_template_filter` decorator.
:param name: the optional name of the filter, otherwise the
function name will be used.
"""
def register_template(state: BlueprintSetupState) -> None:
state.app.jinja_env.filters[name or f.__name__] = f
self.record_once(register_template)
def app_template_test(
self, name: t.Optional[str] = None
) -> t.Callable[[TemplateTestCallable], TemplateTestCallable]:
"""Register a custom template test, available application wide. Like
:meth:`Flask.template_test` but for a blueprint.
.. versionadded:: 0.10
:param name: the optional name of the test, otherwise the
function name will be used.
"""
def decorator(f: TemplateTestCallable) -> TemplateTestCallable:
self.add_app_template_test(f, name=name)
return f
return decorator
def add_app_template_test(
self, f: TemplateTestCallable, name: t.Optional[str] = None
) -> None:
"""Register a custom template test, available application wide. Like
:meth:`Flask.add_template_test` but for a blueprint. Works exactly
like the :meth:`app_template_test` decorator.
.. versionadded:: 0.10
:param name: the optional name of the test, otherwise the
function name will be used.
"""
def register_template(state: BlueprintSetupState) -> None:
state.app.jinja_env.tests[name or f.__name__] = f
self.record_once(register_template)
def app_template_global(
self, name: t.Optional[str] = None
) -> t.Callable[[TemplateGlobalCallable], TemplateGlobalCallable]:
"""Register a custom template global, available application wide. Like
:meth:`Flask.template_global` but for a blueprint.
.. versionadded:: 0.10
:param name: the optional name of the global, otherwise the
function name will be used.
"""
def decorator(f: TemplateGlobalCallable) -> TemplateGlobalCallable:
self.add_app_template_global(f, name=name)
return f
return decorator
def add_app_template_global(
self, f: TemplateGlobalCallable, name: t.Optional[str] = None
) -> None:
"""Register a custom template global, available application wide. Like
:meth:`Flask.add_template_global` but for a blueprint. Works exactly
like the :meth:`app_template_global` decorator.
.. versionadded:: 0.10
:param name: the optional name of the global, otherwise the
function name will be used.
"""
def register_template(state: BlueprintSetupState) -> None:
state.app.jinja_env.globals[name or f.__name__] = f
self.record_once(register_template)
def before_app_request(self, f: BeforeRequestCallable) -> BeforeRequestCallable:
"""Like :meth:`Flask.before_request`. Such a function is executed
before each request, even if outside of a blueprint.
"""
self.record_once(
lambda s: s.app.before_request_funcs.setdefault(None, []).append(f)
)
return f
def before_app_first_request(
self, f: BeforeFirstRequestCallable
) -> BeforeFirstRequestCallable:
"""Like :meth:`Flask.before_first_request`. Such a function is
executed before the first request to the application.
"""
self.record_once(lambda s: s.app.before_first_request_funcs.append(f))
return f
def after_app_request(self, f: AfterRequestCallable) -> AfterRequestCallable:
"""Like :meth:`Flask.after_request` but for a blueprint. Such a function
is executed after each request, even if outside of the blueprint.
"""
self.record_once(
lambda s: s.app.after_request_funcs.setdefault(None, []).append(f)
)
return f
def teardown_app_request(self, f: TeardownCallable) -> TeardownCallable:
"""Like :meth:`Flask.teardown_request` but for a blueprint. Such a
function is executed when tearing down each request, even if outside of
the blueprint.
"""
self.record_once(
lambda s: s.app.teardown_request_funcs.setdefault(None, []).append(f)
)
return f
def app_context_processor(
self, f: TemplateContextProcessorCallable
) -> TemplateContextProcessorCallable:
"""Like :meth:`Flask.context_processor` but for a blueprint. Such a
function is executed each request, even if outside of the blueprint.
"""
self.record_once(
lambda s: s.app.template_context_processors.setdefault(None, []).append(f)
)
return f
def app_errorhandler(self, code: t.Union[t.Type[Exception], int]) -> t.Callable:
"""Like :meth:`Flask.errorhandler` but for a blueprint. This
handler is used for all requests, even if outside of the blueprint.
"""
def decorator(
f: "ErrorHandlerCallable[Exception]",
) -> "ErrorHandlerCallable[Exception]":
self.record_once(lambda s: s.app.errorhandler(code)(f))
return f
return decorator
def app_url_value_preprocessor(
self, f: URLValuePreprocessorCallable
) -> URLValuePreprocessorCallable:
"""Same as :meth:`url_value_preprocessor` but application wide."""
self.record_once(
lambda s: s.app.url_value_preprocessors.setdefault(None, []).append(f)
)
return f
def app_url_defaults(self, f: URLDefaultCallable) -> URLDefaultCallable:
"""Same as :meth:`url_defaults` but application wide."""
self.record_once(
lambda s: s.app.url_default_functions.setdefault(None, []).append(f)
)
return f