Two ways to get PHP to support page fallback _php tips

In the development process, often because the form error and return to the page when the information is missing, in order to support page bounce, can be achieved in two ways.
First, use the header method to set the message header Cache-control


Header (' Cache-control:private, Must-revalidate '); Support page Bounce



Second, using the Session_cache_limiter method


Note to write before the Session_Start method
Session_cache_limiter (' Private, must-revalidate ');




Ps:cache-control Message Header Field description
CACHE-CONTROL Specifies the caching mechanism that the request and response follow. Setting Cache-control in a request message or in a response message does not modify the caching process during another message handling process. The cached instructions at 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 instructions in each message have the following meanings:

Public indicates that the response can be cached by any buffer.
Private indicates that the entire or partial response message for a single user cannot be handled by the shared cache. This allows the server to simply describe a partial response message from the user, which is not valid for other users ' requests.
No-cache indicates that a request or response message cannot be cached
No-store is used to prevent important information from being inadvertently released. Sending in a request message will not use caching for both request and response messages.
Max-age indicates that the client can receive a response that is not longer than the specified time in seconds.
Min-fresh indicates that the client can receive response times that are less than the current time plus a specified time.
Max-stale indicates that the client can receive response messages that exceed the timeout period. If you specify a value for the Max-stale message, the client can receive a response message that exceeds the specified value for the timeout period.