Flask 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.