Solved Whether the $_POST variable is reliable for a multiple PHP call?

[fender0107401]

Page A run js (ajax post) to call a back end php script PA and the script use $_POST['foo'] to get the parameter (assume here foo = 1024).

Page B run js (ajax post) to call a back end php script PB and the script use $_POST['foo'] to get the parameter (assume here foo = 2048).

If same user with same browser run Page A and Page B, the back end php script will get "foo = 1024" or "foo = 2048"?

Maybe that is a simple question, but I can't find related docs.

 

[fender0107401]

I fond this page: https://www.php.net/manual/en/language.variables.superglobals.php

Several predefined variables in PHP are "superglobals", which means they are available in all scopes throughout a script. There is no need to do global $variable; to access them within functions or methods.

These superglobal variables are:

• $GLOBALS
• $_SERVER
• $_GET
• $_POST
• $_FILES
• $_COOKIE
• $_SESSION
• $_REQUEST
• $_ENV

So, the the back end php script PA and PB do not share the $_POST variable, right?

 

[richardtoohey2]

I'm not sure what you mean.

Each AJAX post will be to a separate PHP process, and those processes won't interact - is that what you mean? Page A and script PA and Page B and script PB won't have anything shared or any knowledge of each other.

There's no state in HTTP unless you use some sort of sessions or cookies.

Superglobals are as you say, per script.

 

[richardtoohey2]

If same user with same browser run Page A and Page B, the back end php script will get "foo = 1024" or "foo = 2048"?

It will get both.

One instance will get the HTTP header with foo set to 1024 (from page A)
Another instance will get the HTTP header with foo set to 2048 (from page B)

This is more about how http works rather than PHP - maybe that's why you are not finding what you are looking for in the PHP documentation:

An overview of HTTP - HTTP | MDN

HTTP is a protocol for fetching resources such as HTML documents. It is the foundation of any data exchange on the Web and it is a client-server protocol, which means requests are initiated by the recipient, usually the Web browser. A complete document is reconstructed from the different...

developer.mozilla.org

HTTP is stateless: there is no link between two requests being successively carried out on the same connection. This immediately has the prospect of being problematic for users attempting to interact with certain pages coherently, for example, using e-commerce shopping baskets. But while the core of HTTP itself is stateless, HTTP cookies allow the use of stateful sessions. Using header extensibility, HTTP Cookies are added to the workflow, allowing session creation on each HTTP request to share the same context, or the same state.

 

[fender0107401]

Got that.

 

[zirias@]

It will get both.

One instance will get the HTTP header with foo set to 1024 (from page A)
Another instance will get the HTTP header with foo set to 2048 (from page B)

PHP's $_POST is filled from the parsed body of a request, not from headers.

 

[richardtoohey2]

Yes, I worded that poorly - maybe http request would have been better wording.

But think I’m correct in saying the OP’s question more to do with how HTTP works rather than PHP.

So how POST works:

POST - HTTP | MDN

The HTTP POST method sends data to the server. The type of the body of the request is indicated by the Content-Type header.

developer.mozilla.org