Calling wp-blog-header.php from inside a PHP function

Currently having this same problem. Ever find a solution?

Yeah, very weird that nobody seems to care too much.

I was having the same problem you guys are having. After pulling my hair off for a few hours, I got to solve my problem, here it goes…

I was sending some information via AJAX to the functions.php file, under my TEMPLATEPATH directory. On the top of the functions.php file, I was including a function that checked if there was something set in the $_POST variable, then executed a specific action.

And guess what?, the error was the same you guys are having, so I started to get deep into the problem.

For some reason, if you use any php file used by wordpress internally, as the POST action for your AJAX request or form, it doesn’t load the WordPress environment correctly, so I decided to create a separate php file, unrelated to the theme itself, called it postdata.php and added the following code:

// Available actions
$actions = Array('request_gallery_slot');

if (count($_POST)) {
		if ( in_array($_POST['action'], $actions) ) {
			// Initialize WordPress
			$wp_root = explode('wp-content', $_SERVER['SCRIPT_FILENAME']);
			$wp_root = $wp_root[0];
			chdir($wp_root);
			if (!function_exists('add_action')) {
				if (file_exists('wp-load.php')) {
					require_once('wp-load.php');
				} else {
					require_once('wp-config.php');
				}
			}

			// Determine the action
			switch ( $_POST['action'] ) {
				case 'request_gallery_slot':
					$slot = $_POST['slot'];
					get_gallery_slot($slot);
			}
		}
	}

That is working perfectly, hope this helps.

This problem occured for me when I included wp-blog-header.php from within a function (class method actually). This caused the global variables that WP sets to not be global for real, thus not being accessible by calling global $var. You get the error because $wpdb is global, but not really. I solved this by adding:

global $wpdb

Beneath the line: (in wp-settings.php on the line 269)

require_wp_db();

So the result looks like this:

require (ABSPATH . WPINC . '/compat.php');
require (ABSPATH . WPINC . '/functions.php');
require (ABSPATH . WPINC . '/classes.php');

require_wp_db();
global $wpdb; // Look look! Over here! line 270 in wp-settings.php

if ( !empty($wpdb->error) )
	dead_db();

This however did not solve the problem. The same kind of error popped up elsewhere because of dependencies of other global variables in other places.

I just added the include(‘blog/wp-blog-header.php’); in my index.php outside of any functions (this is not the best solution for me because it means I have to include WP in all my page requests even when WP is not needed.)