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app.py
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app.py
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# -*- coding: utf-8 -*-
"""
flask.app
~~~~~~~~~
This module implements the central WSGI application object.
:copyright: © 2010 by the Pallets team.
:license: BSD, see LICENSE for more details.
"""
import os
import sys
import warnings
from datetime import timedelta
from functools import update_wrapper
from itertools import chain
from threading import Lock
from werkzeug.datastructures import Headers, ImmutableDict
from werkzeug.exceptions import BadRequest, BadRequestKeyError, HTTPException, \
InternalServerError, MethodNotAllowed, default_exceptions
from werkzeug.routing import BuildError, Map, RequestRedirect, \
RoutingException, Rule
from . import cli, json
from ._compat import integer_types, reraise, string_types, text_type
from .config import Config, ConfigAttribute
from .ctx import AppContext, RequestContext, _AppCtxGlobals
from .globals import _request_ctx_stack, g, request, session
from .helpers import (
_PackageBoundObject,
_endpoint_from_view_func, find_package, get_env, get_debug_flag,
get_flashed_messages, locked_cached_property, url_for, get_load_dotenv
)
from .logging import create_logger
from .sessions import SecureCookieSessionInterface
from .signals import appcontext_tearing_down, got_request_exception, \
request_finished, request_started, request_tearing_down
from .templating import DispatchingJinjaLoader, Environment, \
_default_template_ctx_processor
from .wrappers import Request, Response
# a singleton sentinel value for parameter defaults
_sentinel = object()
def _make_timedelta(value):
if not isinstance(value, timedelta):
return timedelta(seconds=value)
return value
def setupmethod(f):
"""Wraps a method so that it performs a check in debug mode if the
first request was already handled.
"""
def wrapper_func(self, *args, **kwargs):
if self.debug and self._got_first_request:
raise AssertionError('A setup function was called after the '
'first request was handled. This usually indicates a bug '
'in the application where a module was not imported '
'and decorators or other functionality was called too late.\n'
'To fix this make sure to import all your view modules, '
'database models and everything related at a central place '
'before the application starts serving requests.')
return f(self, *args, **kwargs)
return update_wrapper(wrapper_func, f)
class Flask(_PackageBoundObject):
"""The flask object implements a WSGI application and acts as the central
object. It is passed the name of the module or package of the
application. Once it is created it will act as a central registry for
the view functions, the URL rules, template configuration and much more.
The name of the package is used to resolve resources from inside the
package or the folder the module is contained in depending on if the
package parameter resolves to an actual python package (a folder with
an :file:`__init__.py` file inside) or a standard module (just a ``.py`` file).
For more information about resource loading, see :func:`open_resource`.
Usually you create a :class:`Flask` instance in your main module or
in the :file:`__init__.py` file of your package like this::
from flask import Flask
app = Flask(__name__)
.. admonition:: About the First Parameter
The idea of the first parameter is to give Flask an idea of what
belongs to your application. This name is used to find resources
on the filesystem, can be used by extensions to improve debugging
information and a lot more.
So it's important what you provide there. If you are using a single
module, `__name__` is always the correct value. If you however are
using a package, it's usually recommended to hardcode the name of
your package there.
For example if your application is defined in :file:`yourapplication/app.py`
you should create it with one of the two versions below::
app = Flask('yourapplication')
app = Flask(__name__.split('.')[0])
Why is that? The application will work even with `__name__`, thanks
to how resources are looked up. However it will make debugging more
painful. Certain extensions can make assumptions based on the
import name of your application. For example the Flask-SQLAlchemy
extension will look for the code in your application that triggered
an SQL query in debug mode. If the import name is not properly set
up, that debugging information is lost. (For example it would only
pick up SQL queries in `yourapplication.app` and not
`yourapplication.views.frontend`)
.. versionadded:: 0.7
The `static_url_path`, `static_folder`, and `template_folder`
parameters were added.
.. versionadded:: 0.8
The `instance_path` and `instance_relative_config` parameters were
added.
.. versionadded:: 0.11
The `root_path` parameter was added.
.. versionadded:: 1.0
The ``host_matching`` and ``static_host`` parameters were added.
.. versionadded:: 1.0
The ``subdomain_matching`` parameter was added. Subdomain
matching needs to be enabled manually now. Setting
:data:`SERVER_NAME` does not implicitly enable it.
:param import_name: the name of the application package
:param static_url_path: can be used to specify a different path for the
static files on the web. Defaults to the name
of the `static_folder` folder.
:param static_folder: the folder with static files that should be served
at `static_url_path`. Defaults to the ``'static'``
folder in the root path of the application.
:param static_host: the host to use when adding the static route.
Defaults to None. Required when using ``host_matching=True``
with a ``static_folder`` configured.
:param host_matching: set ``url_map.host_matching`` attribute.
Defaults to False.
:param subdomain_matching: consider the subdomain relative to
:data:`SERVER_NAME` when matching routes. Defaults to False.
:param template_folder: the folder that contains the templates that should
be used by the application. Defaults to
``'templates'`` folder in the root path of the
application.
:param instance_path: An alternative instance path for the application.
By default the folder ``'instance'`` next to the
package or module is assumed to be the instance
path.
:param instance_relative_config: if set to ``True`` relative filenames
for loading the config are assumed to
be relative to the instance path instead
of the application root.
:param root_path: Flask by default will automatically calculate the path
to the root of the application. In certain situations
this cannot be achieved (for instance if the package
is a Python 3 namespace package) and needs to be
manually defined.
"""
#: The class that is used for request objects. See :class:`~flask.Request`
#: for more information.
request_class = Request
#: The class that is used for response objects. See
#: :class:`~flask.Response` for more information.
response_class = Response
#: The class that is used for the Jinja environment.
#:
#: .. versionadded:: 0.11
jinja_environment = Environment
#: The class that is used for the :data:`~flask.g` instance.
#:
#: Example use cases for a custom class:
#:
#: 1. Store arbitrary attributes on flask.g.
#: 2. Add a property for lazy per-request database connectors.
#: 3. Return None instead of AttributeError on unexpected attributes.
#: 4. Raise exception if an unexpected attr is set, a "controlled" flask.g.
#:
#: In Flask 0.9 this property was called `request_globals_class` but it
#: was changed in 0.10 to :attr:`app_ctx_globals_class` because the
#: flask.g object is now application context scoped.
#:
#: .. versionadded:: 0.10
app_ctx_globals_class = _AppCtxGlobals
#: The class that is used for the ``config`` attribute of this app.
#: Defaults to :class:`~flask.Config`.
#:
#: Example use cases for a custom class:
#:
#: 1. Default values for certain config options.
#: 2. Access to config values through attributes in addition to keys.
#:
#: .. versionadded:: 0.11
config_class = Config
#: The testing flag. Set this to ``True`` to enable the test mode of
#: Flask extensions (and in the future probably also Flask itself).
#: For example this might activate test helpers that have an
#: additional runtime cost which should not be enabled by default.
#:
#: If this is enabled and PROPAGATE_EXCEPTIONS is not changed from the
#: default it's implicitly enabled.
#:
#: This attribute can also be configured from the config with the
#: ``TESTING`` configuration key. Defaults to ``False``.
testing = ConfigAttribute('TESTING')
#: If a secret key is set, cryptographic components can use this to
#: sign cookies and other things. Set this to a complex random value
#: when you want to use the secure cookie for instance.
#:
#: This attribute can also be configured from the config with the
#: :data:`SECRET_KEY` configuration key. Defaults to ``None``.
secret_key = ConfigAttribute('SECRET_KEY')
#: The secure cookie uses this for the name of the session cookie.
#:
#: This attribute can also be configured from the config with the
#: ``SESSION_COOKIE_NAME`` configuration key. Defaults to ``'session'``
session_cookie_name = ConfigAttribute('SESSION_COOKIE_NAME')
#: A :class:`~datetime.timedelta` which is used to set the expiration
#: date of a permanent session. The default is 31 days which makes a
#: permanent session survive for roughly one month.
#:
#: This attribute can also be configured from the config with the
#: ``PERMANENT_SESSION_LIFETIME`` configuration key. Defaults to
#: ``timedelta(days=31)``
permanent_session_lifetime = ConfigAttribute('PERMANENT_SESSION_LIFETIME',
get_converter=_make_timedelta)
#: A :class:`~datetime.timedelta` which is used as default cache_timeout
#: for the :func:`send_file` functions. The default is 12 hours.
#:
#: This attribute can also be configured from the config with the
#: ``SEND_FILE_MAX_AGE_DEFAULT`` configuration key. This configuration
#: variable can also be set with an integer value used as seconds.
#: Defaults to ``timedelta(hours=12)``
send_file_max_age_default = ConfigAttribute('SEND_FILE_MAX_AGE_DEFAULT',
get_converter=_make_timedelta)
#: Enable this if you want to use the X-Sendfile feature. Keep in
#: mind that the server has to support this. This only affects files
#: sent with the :func:`send_file` method.
#:
#: .. versionadded:: 0.2
#:
#: This attribute can also be configured from the config with the
#: ``USE_X_SENDFILE`` configuration key. Defaults to ``False``.
use_x_sendfile = ConfigAttribute('USE_X_SENDFILE')
#: The JSON encoder class to use. Defaults to :class:`~flask.json.JSONEncoder`.
#:
#: .. versionadded:: 0.10
json_encoder = json.JSONEncoder
#: The JSON decoder class to use. Defaults to :class:`~flask.json.JSONDecoder`.
#:
#: .. versionadded:: 0.10
json_decoder = json.JSONDecoder
#: Options that are passed directly to the Jinja2 environment.
jinja_options = ImmutableDict(
extensions=['jinja2.ext.autoescape', 'jinja2.ext.with_']
)
#: Default configuration parameters.
default_config = ImmutableDict({
'ENV': None,
'DEBUG': None,
'TESTING': False,
'PROPAGATE_EXCEPTIONS': None,
'PRESERVE_CONTEXT_ON_EXCEPTION': None,
'SECRET_KEY': None,
'PERMANENT_SESSION_LIFETIME': timedelta(days=31),
'USE_X_SENDFILE': False,
'SERVER_NAME': None,
'APPLICATION_ROOT': '/',
'SESSION_COOKIE_NAME': 'session',
'SESSION_COOKIE_DOMAIN': None,
'SESSION_COOKIE_PATH': None,
'SESSION_COOKIE_HTTPONLY': True,
'SESSION_COOKIE_SECURE': False,
'SESSION_COOKIE_SAMESITE': None,
'SESSION_REFRESH_EACH_REQUEST': True,
'MAX_CONTENT_LENGTH': None,
'SEND_FILE_MAX_AGE_DEFAULT': timedelta(hours=12),
'TRAP_BAD_REQUEST_ERRORS': None,
'TRAP_HTTP_EXCEPTIONS': False,
'EXPLAIN_TEMPLATE_LOADING': False,
'PREFERRED_URL_SCHEME': 'http',
'JSON_AS_ASCII': True,
'JSON_SORT_KEYS': True,
'JSONIFY_PRETTYPRINT_REGULAR': False,
'JSONIFY_MIMETYPE': 'application/json',
'TEMPLATES_AUTO_RELOAD': None,
'MAX_COOKIE_SIZE': 4093,
})
#: The rule object to use for URL rules created. This is used by
#: :meth:`add_url_rule`. Defaults to :class:`werkzeug.routing.Rule`.
#:
#: .. versionadded:: 0.7
url_rule_class = Rule
#: the test client that is used with when `test_client` is used.
#:
#: .. versionadded:: 0.7
test_client_class = None
#: The :class:`~click.testing.CliRunner` subclass, by default
#: :class:`~flask.testing.FlaskCliRunner` that is used by
#: :meth:`test_cli_runner`. Its ``__init__`` method should take a
#: Flask app object as the first argument.
#:
#: .. versionadded:: 1.0
test_cli_runner_class = None
#: the session interface to use. By default an instance of
#: :class:`~flask.sessions.SecureCookieSessionInterface` is used here.
#:
#: .. versionadded:: 0.8
session_interface = SecureCookieSessionInterface()
# 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,
import_name,
static_url_path=None,
static_folder='static',
static_host=None,
host_matching=False,
subdomain_matching=False,
template_folder='templates',
instance_path=None,
instance_relative_config=False,
root_path=None
):
_PackageBoundObject.__init__(
self,
import_name,
template_folder=template_folder,
root_path=root_path
)
if static_url_path is not None:
self.static_url_path = static_url_path
if static_folder is not None:
self.static_folder = static_folder
if instance_path is None:
instance_path = self.auto_find_instance_path()
elif not os.path.isabs(instance_path):
raise ValueError(
'If an instance path is provided it must be absolute.'
' A relative path was given instead.'
)
#: Holds the path to the instance folder.
#:
#: .. versionadded:: 0.8
self.instance_path = instance_path
#: The configuration dictionary as :class:`Config`. This behaves
#: exactly like a regular dictionary but supports additional methods
#: to load a config from files.
self.config = self.make_config(instance_relative_config)
#: A dictionary of all view functions registered. The keys will
#: be function names which are also used to generate URLs and
#: the values are the function objects themselves.
#: To register a view function, use the :meth:`route` decorator.
self.view_functions = {}
#: A dictionary of all registered error handlers. The key is ``None``
#: for error handlers active on the application, otherwise the key is
#: the name of the blueprint. Each key points to another dictionary
#: where the key is the status code of the http exception. The
#: special key ``None`` points to a list of tuples where the first item
#: is the class for the instance check and the second the error handler
#: function.
#:
#: To register an error handler, use the :meth:`errorhandler`
#: decorator.
self.error_handler_spec = {}
#: A list of functions that are called when :meth:`url_for` raises a
#: :exc:`~werkzeug.routing.BuildError`. Each function registered here
#: is called with `error`, `endpoint` and `values`. If a function
#: returns ``None`` or raises a :exc:`BuildError` the next function is
#: tried.
#:
#: .. versionadded:: 0.9
self.url_build_error_handlers = []
#: A dictionary with lists of functions that will be called at the
#: beginning of each request. The key of the dictionary is the name of
#: the blueprint this function is active for, or ``None`` for all
#: requests. To register a function, use the :meth:`before_request`
#: decorator.
self.before_request_funcs = {}
#: A list of functions that will be called at the beginning of the
#: first request to this instance. To register a function, use the
#: :meth:`before_first_request` decorator.
#:
#: .. versionadded:: 0.8
self.before_first_request_funcs = []
#: A dictionary with lists of functions that should be called after
#: each request. The key of the dictionary is the name of the blueprint
#: this function is active for, ``None`` for all requests. This can for
#: example be used to close database connections. To register a function
#: here, use the :meth:`after_request` decorator.
self.after_request_funcs = {}
#: A dictionary with lists of functions that are called after
#: each request, even if an exception has occurred. The key of the
#: dictionary is the name of the blueprint this function is active for,
#: ``None`` for all requests. These functions are not allowed to modify
#: the request, and their return values are ignored. If an exception
#: occurred while processing the request, it gets passed to each
#: teardown_request function. To register a function here, use the
#: :meth:`teardown_request` decorator.
#:
#: .. versionadded:: 0.7
self.teardown_request_funcs = {}
#: A list of functions that are called when the application context
#: is destroyed. Since the application context is also torn down
#: if the request ends this is the place to store code that disconnects
#: from databases.
#:
#: .. versionadded:: 0.9
self.teardown_appcontext_funcs = []
#: A dictionary with lists of functions that are called before the
#: :attr:`before_request_funcs` functions. The key of the dictionary is
#: the name of the blueprint this function is active for, or ``None``
#: for all requests. To register a function, use
#: :meth:`url_value_preprocessor`.
#:
#: .. versionadded:: 0.7
self.url_value_preprocessors = {}
#: A dictionary with lists of functions that can be used as URL value
#: preprocessors. The key ``None`` here is used for application wide
#: callbacks, otherwise the key is the name of the blueprint.
#: Each of these functions has the chance to modify the dictionary
#: of URL values before they are used as the keyword arguments of the
#: view function. For each function registered this one should also
#: provide a :meth:`url_defaults` function that adds the parameters
#: automatically again that were removed that way.
#:
#: .. versionadded:: 0.7
self.url_default_functions = {}
#: A dictionary with list of functions that are called without argument
#: to populate the template context. The key of the dictionary is the
#: name of the blueprint this function is active for, ``None`` for all
#: requests. Each returns a dictionary that the template context is
#: updated with. To register a function here, use the
#: :meth:`context_processor` decorator.
self.template_context_processors = {
None: [_default_template_ctx_processor]
}
#: A list of shell context processor functions that should be run
#: when a shell context is created.
#:
#: .. versionadded:: 0.11
self.shell_context_processors = []
#: all the attached blueprints in a dictionary by name. Blueprints
#: can be attached multiple times so this dictionary does not tell
#: you how often they got attached.
#:
#: .. versionadded:: 0.7
self.blueprints = {}
self._blueprint_order = []
#: a place where extensions can store application specific state. For
#: example this is where an extension could store database engines and
#: similar things. For backwards compatibility extensions should register
#: themselves like this::
#:
#: if not hasattr(app, 'extensions'):
#: app.extensions = {}
#: app.extensions['extensionname'] = SomeObject()
#:
#: The key must match the name of the extension module. For example in
#: case of a "Flask-Foo" extension in `flask_foo`, the key would be
#: ``'foo'``.
#:
#: .. versionadded:: 0.7
self.extensions = {}
#: The :class:`~werkzeug.routing.Map` for this instance. You can use
#: this to change the routing converters after the class was created
#: but before any routes are connected. Example::
#:
#: from werkzeug.routing import BaseConverter
#:
#: class ListConverter(BaseConverter):
#: def to_python(self, value):
#: return value.split(',')
#: def to_url(self, values):
#: return ','.join(super(ListConverter, self).to_url(value)
#: for value in values)
#:
#: app = Flask(__name__)
#: app.url_map.converters['list'] = ListConverter
self.url_map = Map()
self.url_map.host_matching = host_matching
self.subdomain_matching = subdomain_matching
# tracks internally if the application already handled at least one
# request.
self._got_first_request = False
self._before_request_lock = Lock()
# Add a static route using the provided static_url_path, static_host,
# and static_folder if there is a configured static_folder.
# Note we do this without checking if static_folder exists.
# For one, it might be created while the server is running (e.g. during
# development). Also, Google App Engine stores static files somewhere
if self.has_static_folder:
assert bool(static_host) == host_matching, 'Invalid static_host/host_matching combination'
self.add_url_rule(
self.static_url_path + '/<path:filename>',
endpoint='static',
host=static_host,
view_func=self.send_static_file
)
#: The click command line context for this application. Commands
#: registered here show up in the :command:`flask` command once the
#: application has been discovered. The default commands are
#: provided by Flask itself and can be overridden.
#:
#: This is an instance of a :class:`click.Group` object.
self.cli = cli.AppGroup(self.name)
@locked_cached_property
def name(self):
"""The name of the application. This is usually the import name
with the difference that it's guessed from the run file if the
import name is main. This name is used as a display name when
Flask needs the name of the application. It can be set and overridden
to change the value.
.. versionadded:: 0.8
"""
if self.import_name == '__main__':
fn = getattr(sys.modules['__main__'], '__file__', None)
if fn is None:
return '__main__'
return os.path.splitext(os.path.basename(fn))[0]
return self.import_name
@property
def propagate_exceptions(self):
"""Returns the value of the ``PROPAGATE_EXCEPTIONS`` configuration
value in case it's set, otherwise a sensible default is returned.
.. versionadded:: 0.7
"""
rv = self.config['PROPAGATE_EXCEPTIONS']
if rv is not None:
return rv
return self.testing or self.debug
@property
def preserve_context_on_exception(self):
"""Returns the value of the ``PRESERVE_CONTEXT_ON_EXCEPTION``
configuration value in case it's set, otherwise a sensible default
is returned.
.. versionadded:: 0.7
"""
rv = self.config['PRESERVE_CONTEXT_ON_EXCEPTION']
if rv is not None:
return rv
return self.debug
@locked_cached_property
def logger(self):
"""The ``'flask.app'`` logger, a standard Python
:class:`~logging.Logger`.
In debug mode, the logger's :attr:`~logging.Logger.level` will be set
to :data:`~logging.DEBUG`.
If there are no handlers configured, a default handler will be added.
See :ref:`logging` for more information.
.. versionchanged:: 1.0
Behavior was simplified. The logger is always named
``flask.app``. The level is only set during configuration, it
doesn't check ``app.debug`` each time. Only one format is used,
not different ones depending on ``app.debug``. No handlers are
removed, and a handler is only added if no handlers are already
configured.
.. versionadded:: 0.3
"""
return create_logger(self)
@locked_cached_property
def jinja_env(self):
"""The Jinja2 environment used to load templates."""
return self.create_jinja_environment()
@property
def got_first_request(self):
"""This attribute is set to ``True`` if the application started
handling the first request.
.. versionadded:: 0.8
"""
return self._got_first_request
def make_config(self, instance_relative=False):
"""Used to create the config attribute by the Flask constructor.
The `instance_relative` parameter is passed in from the constructor
of Flask (there named `instance_relative_config`) and indicates if
the config should be relative to the instance path or the root path
of the application.
.. versionadded:: 0.8
"""
root_path = self.root_path
if instance_relative:
root_path = self.instance_path
defaults = dict(self.default_config)
defaults['ENV'] = get_env()
defaults['DEBUG'] = get_debug_flag()
return self.config_class(root_path, defaults)
def auto_find_instance_path(self):
"""Tries to locate the instance path if it was not provided to the
constructor of the application class. It will basically calculate
the path to a folder named ``instance`` next to your main file or
the package.
.. versionadded:: 0.8
"""
prefix, package_path = find_package(self.import_name)
if prefix is None:
return os.path.join(package_path, 'instance')
return os.path.join(prefix, 'var', self.name + '-instance')
def open_instance_resource(self, resource, mode='rb'):
"""Opens a resource from the application's instance folder
(:attr:`instance_path`). Otherwise works like
:meth:`open_resource`. Instance resources can also be opened for
writing.
:param resource: the name of the resource. To access resources within
subfolders use forward slashes as separator.
:param mode: resource file opening mode, default is 'rb'.
"""
return open(os.path.join(self.instance_path, resource), mode)
def _get_templates_auto_reload(self):
"""Reload templates when they are changed. Used by
:meth:`create_jinja_environment`.
This attribute can be configured with :data:`TEMPLATES_AUTO_RELOAD`. If
not set, it will be enabled in debug mode.
.. versionadded:: 1.0
This property was added but the underlying config and behavior
already existed.
"""
rv = self.config['TEMPLATES_AUTO_RELOAD']
return rv if rv is not None else self.debug
def _set_templates_auto_reload(self, value):
self.config['TEMPLATES_AUTO_RELOAD'] = value
templates_auto_reload = property(
_get_templates_auto_reload, _set_templates_auto_reload
)
del _get_templates_auto_reload, _set_templates_auto_reload
def create_jinja_environment(self):
"""Creates the Jinja2 environment based on :attr:`jinja_options`
and :meth:`select_jinja_autoescape`. Since 0.7 this also adds
the Jinja2 globals and filters after initialization. Override
this function to customize the behavior.
.. versionadded:: 0.5
.. versionchanged:: 0.11
``Environment.auto_reload`` set in accordance with
``TEMPLATES_AUTO_RELOAD`` configuration option.
"""
options = dict(self.jinja_options)
if 'autoescape' not in options:
options['autoescape'] = self.select_jinja_autoescape
if 'auto_reload' not in options:
options['auto_reload'] = self.templates_auto_reload
rv = self.jinja_environment(self, **options)
rv.globals.update(
url_for=url_for,
get_flashed_messages=get_flashed_messages,
config=self.config,
# request, session and g are normally added with the
# context processor for efficiency reasons but for imported
# templates we also want the proxies in there.
request=request,
session=session,
g=g
)
rv.filters['tojson'] = json.tojson_filter
return rv
def create_global_jinja_loader(self):
"""Creates the loader for the Jinja2 environment. Can be used to
override just the loader and keeping the rest unchanged. It's
discouraged to override this function. Instead one should override
the :meth:`jinja_loader` function instead.
The global loader dispatches between the loaders of the application
and the individual blueprints.
.. versionadded:: 0.7
"""
return DispatchingJinjaLoader(self)
def select_jinja_autoescape(self, filename):
"""Returns ``True`` if autoescaping should be active for the given
template name. If no template name is given, returns `True`.
.. versionadded:: 0.5
"""
if filename is None:
return True
return filename.endswith(('.html', '.htm', '.xml', '.xhtml'))
def update_template_context(self, context):
"""Update the template context with some commonly used variables.
This injects request, session, config and g into the template
context as well as everything template context processors want
to inject. Note that the as of Flask 0.6, the original values
in the context will not be overridden if a context processor
decides to return a value with the same key.
:param context: the context as a dictionary that is updated in place
to add extra variables.
"""
funcs = self.template_context_processors[None]
reqctx = _request_ctx_stack.top
if reqctx is not None:
bp = reqctx.request.blueprint
if bp is not None and bp in self.template_context_processors:
funcs = chain(funcs, self.template_context_processors[bp])
orig_ctx = context.copy()
for func in funcs:
context.update(func())
# make sure the original values win. This makes it possible to
# easier add new variables in context processors without breaking
# existing views.
context.update(orig_ctx)
def make_shell_context(self):
"""Returns the shell context for an interactive shell for this
application. This runs all the registered shell context
processors.
.. versionadded:: 0.11
"""
rv = {'app': self, 'g': g}
for processor in self.shell_context_processors:
rv.update(processor())
return rv
#: What environment the app is running in. Flask and extensions may
#: enable behaviors based on the environment, such as enabling debug
#: mode. This maps to the :data:`ENV` config key. This is set by the
#: :envvar:`FLASK_ENV` environment variable and may not behave as
#: expected if set in code.
#:
#: **Do not enable development when deploying in production.**
#:
#: Default: ``'production'``
env = ConfigAttribute('ENV')
def _get_debug(self):
return self.config['DEBUG']
def _set_debug(self, value):
self.config['DEBUG'] = value
self.jinja_env.auto_reload = self.templates_auto_reload
#: Whether debug mode is enabled. When using ``flask run`` to start
#: the development server, an interactive debugger will be shown for
#: unhandled exceptions, and the server will be reloaded when code
#: changes. This maps to the :data:`DEBUG` config key. This is
#: enabled when :attr:`env` is ``'development'`` and is overridden
#: by the ``FLASK_DEBUG`` environment variable. It may not behave as
#: expected if set in code.
#:
#: **Do not enable debug mode when deploying in production.**
#:
#: Default: ``True`` if :attr:`env` is ``'development'``, or
#: ``False`` otherwise.
debug = property(_get_debug, _set_debug)
del _get_debug, _set_debug
def run(self, host=None, port=None, debug=None,
load_dotenv=True, **options):
"""Runs the application on a local development server.
Do not use ``run()`` in a production setting. It is not intended to
meet security and performance requirements for a production server.
Instead, see :ref:`deployment` for WSGI server recommendations.
If the :attr:`debug` flag is set the server will automatically reload
for code changes and show a debugger in case an exception happened.
If you want to run the application in debug mode, but disable the
code execution on the interactive debugger, you can pass
``use_evalex=False`` as parameter. This will keep the debugger's
traceback screen active, but disable code execution.
It is not recommended to use this function for development with
automatic reloading as this is badly supported. Instead you should
be using the :command:`flask` command line script's ``run`` support.
.. admonition:: Keep in Mind
Flask will suppress any server error with a generic error page
unless it is in debug mode. As such to enable just the
interactive debugger without the code reloading, you have to
invoke :meth:`run` with ``debug=True`` and ``use_reloader=False``.
Setting ``use_debugger`` to ``True`` without being in debug mode
won't catch any exceptions because there won't be any to
catch.
:param host: the hostname to listen on. Set this to ``'0.0.0.0'`` to
have the server available externally as well. Defaults to
``'127.0.0.1'`` or the host in the ``SERVER_NAME`` config variable
if present.
:param port: the port of the webserver. Defaults to ``5000`` or the
port defined in the ``SERVER_NAME`` config variable if present.
:param debug: if given, enable or disable debug mode. See
:attr:`debug`.
:param load_dotenv: Load the nearest :file:`.env` and :file:`.flaskenv`
files to set environment variables. Will also change the working
directory to the directory containing the first file found.
:param options: the options to be forwarded to the underlying Werkzeug
server. See :func:`werkzeug.serving.run_simple` for more
information.
.. versionchanged:: 1.0
If installed, python-dotenv will be used to load environment
variables from :file:`.env` and :file:`.flaskenv` files.
If set, the :envvar:`FLASK_ENV` and :envvar:`FLASK_DEBUG`
environment variables will override :attr:`env` and
:attr:`debug`.
Threaded mode is enabled by default.
.. versionchanged:: 0.10
The default port is now picked from the ``SERVER_NAME``
variable.
"""
# Change this into a no-op if the server is invoked from the
# command line. Have a look at cli.py for more information.
if os.environ.get('FLASK_RUN_FROM_CLI') == 'true':
from .debughelpers import explain_ignored_app_run
explain_ignored_app_run()
return
if get_load_dotenv(load_dotenv):
cli.load_dotenv()
# if set, let env vars override previous values
if 'FLASK_ENV' in os.environ:
self.env = get_env()
self.debug = get_debug_flag()
elif 'FLASK_DEBUG' in os.environ:
self.debug = get_debug_flag()
# debug passed to method overrides all other sources
if debug is not None:
self.debug = bool(debug)
_host = '127.0.0.1'
_port = 5000
server_name = self.config.get('SERVER_NAME')
sn_host, sn_port = None, None
if server_name:
sn_host, _, sn_port = server_name.partition(':')
host = host or sn_host or _host
port = int(port or sn_port or _port)
options.setdefault('use_reloader', self.debug)
options.setdefault('use_debugger', self.debug)
options.setdefault('threaded', True)
cli.show_server_banner(self.env, self.debug, self.name, False)
from werkzeug.serving import run_simple
try:
run_simple(host, port, self, **options)
finally:
# reset the first request information if the development server
# reset normally. This makes it possible to restart the server
# without reloader and that stuff from an interactive shell.
self._got_first_request = False
def test_client(self, use_cookies=True, **kwargs):
"""Creates a test client for this application. For information
about unit testing head over to :ref:`testing`.
Note that if you are testing for assertions or exceptions in your
application code, you must set ``app.testing = True`` in order for the
exceptions to propagate to the test client. Otherwise, the exception
will be handled by the application (not visible to the test client) and
the only indication of an AssertionError or other exception will be a
500 status code response to the test client. See the :attr:`testing`
attribute. For example::
app.testing = True
client = app.test_client()
The test client can be used in a ``with`` block to defer the closing down
of the context until the end of the ``with`` block. This is useful if
you want to access the context locals for testing::
with app.test_client() as c:
rv = c.get('/?vodka=42')
assert request.args['vodka'] == '42'
Additionally, you may pass optional keyword arguments that will then
be passed to the application's :attr:`test_client_class` constructor.
For example::
from flask.testing import FlaskClient
class CustomClient(FlaskClient):
def __init__(self, *args, **kwargs):
self._authentication = kwargs.pop("authentication")
super(CustomClient,self).__init__( *args, **kwargs)
app.test_client_class = CustomClient
client = app.test_client(authentication='Basic ....')
See :class:`~flask.testing.FlaskClient` for more information.
.. versionchanged:: 0.4
added support for ``with`` block usage for the client.
.. versionadded:: 0.7
The `use_cookies` parameter was added as well as the ability
to override the client to be used by setting the
:attr:`test_client_class` attribute.
.. versionchanged:: 0.11
Added `**kwargs` to support passing additional keyword arguments to
the constructor of :attr:`test_client_class`.