Including wp-blog-header.php from functions.php remote call?

Question

I have a script that's called from my functions.php file (via an ajax .get) that needs to have access to WP's get_option() method in order to retrieve some values it needs to process.

However, although the file works great in the majority of sites where it resides, on just a few installations, I'm having problems with the script operating (chrome's javascript console reports a 404 (not found) on color.php.

//jQuery calls the file color.php

$('#my_theme_switcher').change
(
    function() 
    {
        $.get
        ('<?php echo get_bloginfo('template_directory') ?>/color.php', 
        {theme: 'test', spot: '1'}, 
        function(data)
            {
                doColor('#theme_header_color', data);
            }
        );
    }
);


Here is the file color.php

<?php
require_once('../../../wp-blog-header.php');
echo 'all good';
?>

In this case, I never get the echo since it appears that the require statement has failed to load the wp-blog-header.php

Is there an alternative way of including the header file in order to be able to call get_option()?

Answer 1

You shouldn't need to make direct calls to your theme files - use the AJAX API, and make all requests to admin-ajax.php (that way, WordPress'll be loaded for you, and you won't need to assume the file hierarchy in order to load it manually).

$.get(
    '<?php echo admin_url( 'admin-ajax.php' ) ?>',

    {
        "color_theme" : "test",
        "color_spot" : "1",
        "action" : "change_color"
    },

    function( data ) {
        doColor( '#theme_header_color', data );
    }
);

And in functions.php;

function __do_color_ajax()
{
    $theme = $_GET['color_theme'];
    $spot = $_GET['color_spot'];

    // do something

    die( 'AJAX output' );
}
add_action( 'wp_ajax_nopriv_change_color', '__do_color_ajax' );

See how the suffix of the hook, wp_ajax_nopriv_change_color, matches the action variable in the AJAX request? See this SE answer for more info.

Note I've also prefixed the other AJAX request variables, as you should namespace custom $_GET and $_POST variables in the same way you do PHP variables and functions.

Also check out the codex on the AJAX API.

Answer 2

Just change the way you make the include in your color.php to:

require($_SERVER['DOCUMENT_ROOT'].'./wp-blog-header.php');