Flask Session Management: Maintaining User Login Status
This article introduces session management in Flask, with the core being the implementation of user state maintenance through the `session` object. Session management enables the server to remember user states (such as login status) during multi-page navigation, relying on cookies and a secret key for encrypted data storage. To implement this in Flask, first install Flask and set a secure secret key. User login status can be achieved in three steps: ① Login verification: Validate the account password through form submission, and if successful, store the username in `session`; ② Maintain login: Check `session` on the homepage—if present, display a welcome message; otherwise, redirect to the login page; ③ Logout: Clear the user information in `session`. Key considerations include: the secret key must never be exposed; use environment variables to store it in production; sessions expire by default when the browser is closed, and `permanent_session_lifetime` can be set to extend validity; `session` data is encrypted and stored in the user's browser cookies, only containing non-sensitive identifiers (e.g., username), so sensitive information should not be stored here. The core steps are: verifying credentials → setting session → verifying session → clearing session. `session` is suitable for short-term sessions; long-term storage requires combining with a database.
Read MoreFlask Session Management: Implementation of User Login State Persistence
This article introduces Flask's session management, where the core is maintaining user state through the `session` object, implemented based on Cookies. The usage involves two steps: importing `session` and setting a secret key (SECRET_KEY, requiring a random string in production), and setting the session expiration period (default is invalid after browser closure, extendable via `permanent_session_lifetime`). Taking "Login-Verification-Logout" as an example, the process is as follows: the frontend form inputs account credentials, the backend validates them, then sets `session["username"]` with `permanent=True` to achieve persistent login. The `login_required` decorator checks the session to ensure only logged-in users access sensitive pages. During logout, `session.pop` is used to clear the state. For security, the secret key must be kept confidential (avoid hardcoding), and the session should only store necessary information (e.g., user ID) without sensitive data. Through these steps, persistent management of user login status can be achieved, enhancing website user experience.
Read MoreFlask Session Management: Basic Applications of Cookies and Sessions
This article introduces two core methods of session management in Flask and their applications. Session management enables websites to "remember" user states (such as login information), which Flask implements through Cookies and Sessions. Cookies are small data (approximately 4KB) stored on the client side (browser), suitable for non-sensitive temporary information (e.g., usernames, theme settings). They can be set using `response.set_cookie()` and read with `request.cookies.get()`, but users can disable them, and they are not suitable for sensitive information. Sessions are stored on the server side, offering higher security and suitable for sensitive data (e.g., user IDs). A `secret_key` must first be set for encryption, and they are stored/retrieved via the `session` object, with clearing done using `pop()` or `clear()`. By default, they use in-memory storage, which is lost upon server restart; Redis persistence is recommended for production environments. Comparison: Cookies are lightweight and simple but less secure, while Sessions are secure and reliable but increase server pressure. In actual development, they are often used in combination: Cookies store the Session ID, and Sessions store core user states.
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