Two implementation methods of php page rollback

Have you ever encountered such a situation: when you return to the page after a form error occurs, all the information you filled in before is gone. This article introduces two methods to support PHP page rollback for your reference.

Method 1, use the Header method to set the message header Cache-control

header('Cache-control: private, must-revalidate'); //支持页面回跳

Method 2, use session_cache_limiter method

//必须写在session_start方法之前，否则报错。
session_cache_limiter('private, must-revalidate');

Attached, Cache-Control message header field description Cache-Control specifies the caching mechanism that requests and responses follow. Setting Cache-Control in a request message or response message does not modify the caching process during the processing of another message. The cache instructions during the request include no-cache, no-store, max-age, max-stale, min-fresh, only-if-cached, and the instructions in the response message include public, private, no-cache, no-store, no-transform, must-revalidate, proxy-revalidate, max-age.

The meaning of each message command: 1. Public indicates that the response can be cached by any cache area. 2. Private indicates that all or part of the response message for a single user cannot be processed by the shared cache. This allows the server to only describe a partial response from a user that is not valid for other users' requests. 3. no-cache indicates that the request or response message cannot be cached 4. no-store is used to prevent important information from being released unintentionally. Sending it in the request message will cause both the request and response messages to use caching. 5. max-age indicates that the client can receive responses with a lifetime no greater than the specified time (in seconds). 6. min-fresh indicates that the client can receive a response with a response time less than the current time plus the specified time. 7. max-stale indicates that the client can receive response messages beyond the timeout period. If you specify a value for max-stale messages, the client can receive response messages that exceed the specified value of the timeout period. For more detailed information about cache-control, please refer to: php file header information detailed explanation .

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