get_current_user_id() returning Zero 0

问题

get_current_user_id() is returning 0 for following codes. I do tried some solution available on stack overflow but somehow not working for me. I'm expecting explanation why its returning zero and how to fix?

P.S: I'm calling get_current_user_id() from external php page and included '../wp-blog-header.php' for that.

Code:

<?php
require('../wp-blog-header.php');
get_header();

$user_ID = get_current_user_id(); 
echo $user_ID;

?> 

回答1:

You have to call wordpress proccess of user authentication. Try adding the following code before get_current_user_id();, if it doesn't solve your problem it'll at least point you the right direction:

$user_id = apply_filters( 'determine_current_user', false );
wp_set_current_user( $user_id );

Hope it helps!

回答2:

This is likely a result of including wp-blog-header.php directly in your external file. From the Codex on get_current_user_id():

The user's ID, if there is a current user; otherwise 0.

I'm not sure what you're trying to do, but the correct method would be to add this logic to functions.php under the correct action hook, or by writing a custom plugin. By doing one of those two things, you will have access to the authenticated user.

回答3:

if you are using ajax then may be in some browser versions we can't get id by get_current_user_id() for this we can use xhrFields in over ajax then it will work fine. if the problem with the browser version.

        jQuery.ajax({
            type: "POST",
            xhrFields: {
                withCredentials: true
            },
            cache: false,

来源：https://stackoverflow.com/questions/36113060/get-current-user-id-returning-zero-0