flask.sessions.SessionInterface

class documentation

class SessionInterface: (source)

Known subclasses: flask.sessions.SecureCookieSessionInterface

The basic interface you have to implement in order to replace the default session interface which uses werkzeug's securecookie implementation. The only methods you have to implement are :meth:`open_session` and :meth:`save_session`, the others have useful defaults which you don't need to change. The session object returned by the :meth:`open_session` method has to provide a dictionary like interface plus the properties and methods from the :class:`SessionMixin`. We recommend just subclassing a dict and adding that mixin:: class Session(dict, SessionMixin): pass If :meth:`open_session` returns ``None`` Flask will call into :meth:`make_null_session` to create a session that acts as replacement if the session support cannot work because some requirement is not fulfilled. The default :class:`NullSession` class that is created will complain that the secret key was not set. To replace the session interface on an application all you have to do is to assign :attr:`flask.Flask.session_interface`:: app = Flask(__name__) app.session_interface = MySessionInterface() Multiple requests with the same session may be sent and handled concurrently. When implementing a new session interface, consider whether reads or writes to the backing store must be synchronized. There is no guarantee on the order in which the session for each request is opened or saved, it will occur in the order that requests begin and end processing. .. versionadded:: 0.8

Method	`get_cookie_domain`	Returns the domain that should be set for the session cookie.
Method	`get_cookie_httponly`	Returns True if the session cookie should be httponly. This currently just returns the value of the ``SESSION_COOKIE_HTTPONLY`` config var.
Method	`get_cookie_name`	The name of the session cookie. Uses``app.config["SESSION_COOKIE_NAME"]``.
Method	`get_cookie_path`	Returns the path for which the cookie should be valid. The default implementation uses the value from the ``SESSION_COOKIE_PATH`` config var if it's set, and falls back to ``APPLICATION_ROOT`` or uses ``/`` if it's ``None``.
Method	`get_cookie_samesite`	Return ``'Strict'`` or ``'Lax'`` if the cookie should use the ``SameSite`` attribute. This currently just returns the value of the :data:`SESSION_COOKIE_SAMESITE` setting.
Method	`get_cookie_secure`	Returns True if the cookie should be secure. This currently just returns the value of the ``SESSION_COOKIE_SECURE`` setting.
Method	`get_expiration_time`	A helper method that returns an expiration date for the session or ``None`` if the session is linked to the browser session. The default implementation returns now + the permanent session lifetime configured on the application.
Method	`is_null_session`	Checks if a given object is a null session. Null sessions are not asked to be saved.
Method	`make_null_session`	Creates a null session which acts as a replacement object if the real session support could not be loaded due to a configuration error. This mainly aids the user experience because the job of the null session is to still support lookup without complaining but modifications are answered with a helpful error message of what failed.
Method	`open_session`	This is called at the beginning of each request, after pushing the request context, before matching the URL.
Method	`save_session`	This is called at the end of each request, after generating a response, before removing the request context. It is skipped if :meth:`is_null_session` returns ``True``.
Method	`should_set_cookie`	Used by session backends to determine if a ``Set-Cookie`` header should be set for this session cookie for this response. If the session has been modified, the cookie is set. If the session is permanent and the ``SESSION_REFRESH_EACH_REQUEST`` config is true, the cookie is always set.
Class Variable	`pickle_based`	Undocumented

def get_cookie_domain(self, app: Flask) -> t.Optional[str]: (source) ¶

Returns the domain that should be set for the session cookie. Uses ``SESSION_COOKIE_DOMAIN`` if it is configured, otherwise falls back to detecting the domain based on ``SERVER_NAME``. Once detected (or if not set at all), ``SESSION_COOKIE_DOMAIN`` is updated to avoid re-running the logic.

def get_cookie_httponly(self, app: Flask) -> bool: (source) ¶

Returns True if the session cookie should be httponly. This currently just returns the value of the ``SESSION_COOKIE_HTTPONLY`` config var.

def get_cookie_name(self, app: Flask) -> str: (source) ¶

The name of the session cookie. Uses``app.config["SESSION_COOKIE_NAME"]``.

def get_cookie_path(self, app: Flask) -> str: (source) ¶

Returns the path for which the cookie should be valid. The default implementation uses the value from the ``SESSION_COOKIE_PATH`` config var if it's set, and falls back to ``APPLICATION_ROOT`` or uses ``/`` if it's ``None``.

def get_cookie_samesite(self, app: Flask) -> str: (source) ¶

Return ``'Strict'`` or ``'Lax'`` if the cookie should use the ``SameSite`` attribute. This currently just returns the value of the :data:`SESSION_COOKIE_SAMESITE` setting.

def get_cookie_secure(self, app: Flask) -> bool: (source) ¶

Returns True if the cookie should be secure. This currently just returns the value of the ``SESSION_COOKIE_SECURE`` setting.

def get_expiration_time(self, app: Flask, session: SessionMixin) -> t.Optional[datetime]: (source) ¶

A helper method that returns an expiration date for the session or ``None`` if the session is linked to the browser session. The default implementation returns now + the permanent session lifetime configured on the application.

def is_null_session(self, obj: object) -> bool: (source) ¶

Checks if a given object is a null session. Null sessions are not asked to be saved. This checks if the object is an instance of :attr:`null_session_class` by default.

def make_null_session(self, app: Flask) -> NullSession: (source) ¶

Creates a null session which acts as a replacement object if the real session support could not be loaded due to a configuration error. This mainly aids the user experience because the job of the null session is to still support lookup without complaining but modifications are answered with a helpful error message of what failed. This creates an instance of :attr:`null_session_class` by default.

def open_session(self, app: Flask, request: Request) -> t.Optional[SessionMixin]: (source) ¶

overridden in flask.sessions.SecureCookieSessionInterface

This is called at the beginning of each request, after pushing the request context, before matching the URL. This must return an object which implements a dictionary-like interface as well as the :class:`SessionMixin` interface. This will return ``None`` to indicate that loading failed in some way that is not immediately an error. The request context will fall back to using :meth:`make_null_session` in this case.

def save_session(self, app: Flask, session: SessionMixin, response: Response): (source) ¶

overridden in flask.sessions.SecureCookieSessionInterface

This is called at the end of each request, after generating a response, before removing the request context. It is skipped if :meth:`is_null_session` returns ``True``.

def should_set_cookie(self, app: Flask, session: SessionMixin) -> bool: (source) ¶

Used by session backends to determine if a ``Set-Cookie`` header should be set for this session cookie for this response. If the session has been modified, the cookie is set. If the session is permanent and the ``SESSION_REFRESH_EACH_REQUEST`` config is true, the cookie is always set. This check is usually skipped if the session was deleted. .. versionadded:: 0.11

pickle_based: bool = (source) ¶

Undocumented