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# -*- coding: utf-8 -*-
"""
flask.blueprints
~~~~~~~~~~~~~~~~
Blueprints are the recommended way to implement larger or more
pluggable applications in Flask 0.7 and later.
:copyright: (c) 2011 by Armin Ronacher.
:license: BSD, see LICENSE for more details.
"""
from functools import update_wrapper
from .helpers import _PackageBoundObject, _endpoint_from_view_func
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:
rule = self.url_prefix + rule
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 blueprint is an object that records
functions that will be called with the
:class:`~flask.blueprint.BlueprintSetupState` later to register functions
or other things on the main application. See :ref:`blueprints` for more
information.
.. versionadded:: 0.7
"""
warn_on_modifications = False
_got_registered_once = False
def __init__(self, name, import_name, static_folder=None,
static_url_path=None, template_folder=None,
url_prefix=None, subdomain=None, url_defaults=None):
_PackageBoundObject.__init__(self, import_name, template_folder)
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 = []
self.view_functions = {}
if url_defaults is None:
url_defaults = {}
self.url_values_defaults = url_defaults
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 a blueprint
on the application. This can be overridden to customize the register
behavior. Keyword arguments from
:func:`~flask.Flask.register_blueprint` are directly forwarded to this
method in the `options` dictionary.
"""
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)
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 endpoint's should not contain dot's"
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.
: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.
: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 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
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