flask/CodeBoarding/Sessions.md

graph LR
    SessionInterface["SessionInterface"]
    SecureCookieSessionInterface["SecureCookieSessionInterface"]
    NullSession["NullSession"]
    SecureCookieSessionInterface -- "implements" --> SessionInterface
    SessionInterface -- "creates" --> NullSession

Component Details

The Sessions component in Flask manages user sessions, allowing applications to store and retrieve user-specific data across multiple requests. It relies on the SessionInterface to define the session management behavior, with SecureCookieSessionInterface providing a secure cookie-based implementation. The component handles session creation, storage, retrieval, and security, ensuring that session data is protected from unauthorized access. When session creation fails, a NullSession is used.

SessionInterface

Defines the interface for implementing session management in Flask. It provides methods for creating, opening, and saving sessions. Custom session storage mechanisms can be implemented by subclassing this interface.

• Related Classes/Methods: flask.src.flask.sessions.SessionInterface (114:284), flask.src.flask.sessions.SessionInterface:make_null_session (164:174)

SecureCookieSessionInterface

Implements session management using secure cookies. It serializes the session data, signs it cryptographically, and stores it in a cookie. This ensures that the session data cannot be tampered with by the client. It extends the SessionInterface.

• Related Classes/Methods: flask.src.flask.sessions.SecureCookieSessionInterface (298:399), flask.src.flask.sessions.SecureCookieSessionInterface:open_session (337:349), flask.src.flask.sessions.SecureCookieSessionInterface:save_session (351:399)

NullSession

Represents a session that does not store any data. It is returned by make_null_session when session creation fails.

• Related Classes/Methods: flask.src.flask.sessions.NullSession (97:111)