# -*- coding: utf-8 -*-
"""
flask.blueprints
~~~~~~~~~~~~~~~~
Blueprints are the recommended way to implement larger or more
pluggable applications in Flask 0.7 and later.
:copyright: 2010 Pallets
:license: BSD-3-Clause
"""
from functools import update_wrapper
from .helpers import _endpoint_from_view_func
from .helpers import _PackageBoundObject
# a singleton sentinel value for parameter defaults
_sentinel = object()
class BlueprintSetupState(object):
"""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, app, options, first_registration):
#: 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
#: 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, endpoint=None, view_func=None, **options):
"""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)
defaults = self.url_defaults
if "defaults" in options:
defaults = dict(defaults, **options.pop("defaults"))
self.app.add_url_rule(
rule,
"%s.%s" % (self.blueprint.name, endpoint),
view_func,
defaults=defaults,
**options
)
class Blueprint(_PackageBoundObject):
"""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 :ref:`blueprints` for more information.
.. 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
: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 this
based on ``import_name``. In certain situations this automatic
detection can fail, so the path can be specified manually
instead.
"""
warn_on_modifications = False
_got_registered_once = False
#: Blueprint local JSON decoder class to use.
#: Set to ``None`` to use the app's :class:`~flask.app.Flask.json_encoder`.
json_encoder = None
#: Blueprint local JSON decoder class to use.
#: Set to ``None`` to use the app's :class:`~flask.app.Flask.json_decoder`.
json_decoder = None
# TODO remove the next three attrs when Sphinx :inherited-members: works
# https://github.com/sphinx-doc/sphinx/issues/741
#: The name of the package or module that this app belongs to. Do not
#: change this once it is set by the constructor.
import_name = None
#: Location of the template files to be added to the template lookup.
#: ``None`` if templates should not be added.
template_folder = None
#: Absolute path to the package on the filesystem. Used to look up
#: resources contained in the package.
root_path = None
def __init__(
self,
name,
import_name,
static_folder=None,
static_url_path=None,
template_folder=None,
url_prefix=None,
subdomain=None,
url_defaults=None,
root_path=None,
cli_group=_sentinel,
):
_PackageBoundObject.__init__(
self, import_name, template_folder, root_path=root_path
)
self.name = name
self.url_prefix = url_prefix
self.subdomain = subdomain
self.static_folder = static_folder
self.static_url_path = static_url_path
self.deferred_functions = []
if url_defaults is None:
url_defaults = {}
self.url_values_defaults = url_defaults
self.cli_group = cli_group
def record(self, func):
"""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):
"""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):
if state.first_registration:
func(state)
return self.record(update_wrapper(wrapper, func))
def make_setup_state(self, app, options, first_registration=False):
"""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(self, app, options, first_registration=False):
"""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`.
:param first_registration: Whether this is the first time this
blueprint has been registered on the application.
"""
self._got_registered_once = True
state = self.make_setup_state(app, options, first_registration)
if self.has_static_folder:
state.add_url_rule(
self.static_url_path + "/<path:filename>",
view_func=self.send_static_file,
endpoint="static",
)
for deferred in self.deferred_functions:
deferred(state)
cli_resolved_group = options.get("cli_group", self.cli_group)
if not self.cli.commands:
return
if cli_resolved_group is None:
app.cli.commands.update(self.cli.commands)
elif cli_resolved_group is _sentinel:
self.cli.name = self.name
app.cli.add_command(self.cli)
else:
self.cli.name = cli_resolved_group
app.cli.add_command(self.cli)
def route(self, rule, **options):
"""Like :meth:`Flask.route` but for a blueprint. The endpoint for the
:func:`url_for` function is prefixed with the name of the blueprint.
"""
def decorator(f):
endpoint = options.pop("endpoint", f.__name__)
self.add_url_rule(rule, endpoint, f, **options)
return f
return decorator
def add_url_rule(self, rule, endpoint=None, view_func=None, **options):
"""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:
assert "." not in endpoint, "Blueprint endpoints should not contain dots"
if view_func and hasattr(view_func, "__name__"):
assert (
"." not in view_func.__name__
), "Blueprint view function name should not contain dots"
self.record(lambda s: s.add_url_rule(rule, endpoint, view_func, **options))
def endpoint(self, endpoint):
"""Like :meth:`Flask.endpoint` but for a blueprint. This does not
prefix the endpoint with the blueprint name, this has to be done
explicitly by the user of this method. If the endpoint is prefixed
with a `.` it will be registered to the current blueprint, otherwise
it's an application independent endpoint.
"""
def decorator(f):
def register_endpoint(state):
state.app.view_functions[endpoint] = f
self.record_once(register_endpoint)
return f
return decorator
def app_template_filter(self, name=None):
"""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):
self.add_app_template_filter(f, name=name)
return f
return decorator
def add_app_template_filter(self, f, name=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):
state.app.jinja_env.filters[name or f.__name__] = f
self.record_once(register_template)
def app_template_test(self, name=None):
"""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):
self.add_app_template_test(f, name=name)
return f
return decorator
def add_app_template_test(self, f, name=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):
state.app.jinja_env.tests[name or f.__name__] = f
self.record_once(register_template)
def app_template_global(self, name=None):
"""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):
self.add_app_template_global(f, name=name)
return f
return decorator
def add_app_template_global(self, f, name=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):
state.app.jinja_env.globals[name or f.__name__] = f
self.record_once(register_template)
def before_request(self, f):
"""Like :meth:`Flask.before_request` but for a blueprint. This function
is only executed before each request that is handled by a function of
that blueprint.
"""
self.record_once(
lambda s: s.app.before_request_funcs.setdefault(self.name, []).append(f)
)
return f
def before_app_request(self, f):
"""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):
"""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_request(self, f):
"""Like :meth:`Flask.after_request` but for a blueprint. This function
is only executed after each request that is handled by a function of
that blueprint.
"""
self.record_once(
lambda s: s.app.after_request_funcs.setdefault(self.name, []).append(f)
)
return f
def after_app_request(self, f):
"""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_request(self, f):
"""Like :meth:`Flask.teardown_request` but for a blueprint. This
function is only executed when tearing down requests handled by a
function of that blueprint. Teardown request functions are executed
when the request context is popped, even when no actual request was
performed.
"""
self.record_once(
lambda s: s.app.teardown_request_funcs.setdefault(self.name, []).append(f)
)
return f
def teardown_app_request(self, f):
"""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 context_processor(self, f):
"""Like :meth:`Flask.context_processor` but for a blueprint. This
function is only executed for requests handled by a blueprint.
"""
self.record_once(
lambda s: s.app.template_context_processors.setdefault(
self.name, []
).append(f)
)
return f
def app_context_processor(self, f):
"""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):
"""Like :meth:`Flask.errorhandler` but for a blueprint. This
handler is used for all requests, even if outside of the blueprint.
"""
def decorator(f):
self.record_once(lambda s: s.app.errorhandler(code)(f))
return f
return decorator
def url_value_preprocessor(self, f):
"""Registers a function as URL value preprocessor for this
blueprint. It's called before the view functions are called and
can modify the url values provided.
"""
self.record_once(
lambda s: s.app.url_value_preprocessors.setdefault(self.name, []).append(f)
)
return f
def url_defaults(self, f):
"""Callback function for URL defaults for this blueprint. It's called
with the endpoint and values and should update the values passed
in place.
"""
self.record_once(
lambda s: s.app.url_default_functions.setdefault(self.name, []).append(f)
)
return f
def app_url_value_preprocessor(self, f):
"""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):
"""Same as :meth:`url_defaults` but application wide.
"""
self.record_once(
lambda s: s.app.url_default_functions.setdefault(None, []).append(f)
)
return f
def errorhandler(self, code_or_exception):
"""Registers an error handler that becomes active for this blueprint
only. Please be aware that routing does not happen local to a
blueprint so an error handler for 404 usually is not handled by
a blueprint unless it is caused inside a view function. Another
special case is the 500 internal server error which is always looked
up from the application.
Otherwise works as the :meth:`~flask.Flask.errorhandler` decorator
of the :class:`~flask.Flask` object.
"""
def decorator(f):
self.record_once(
lambda s: s.app._register_error_handler(self.name, code_or_exception, f)
)
return f
return decorator
def register_error_handler(self, code_or_exception, f):
"""Non-decorator version of the :meth:`errorhandler` error attach
function, akin to the :meth:`~flask.Flask.register_error_handler`
application-wide function of the :class:`~flask.Flask` object but
for error handlers limited to this blueprint.
.. versionadded:: 0.11
"""
self.record_once(
lambda s: s.app._register_error_handler(self.name, code_or_exception, f)
)
