I am running this simple conditional statement on my plugin page:

if (! is_user_logged_in()) {
    add_action('init', 's8w_ajax_login_init');
}

It is throwing a fatal undefined function error for is_user_logged_in. Am I missing something? I have several wp globals on the same page. Do I have to call something else for this to work?

I am running this simple conditional statement on my plugin page:

if (! is_user_logged_in()) {
    add_action('init', 's8w_ajax_login_init');
}

It is throwing a fatal undefined function error for is_user_logged_in. Am I missing something? I have several wp globals on the same page. Do I have to call something else for this to work?

• users
• wp-user-query

• Are you making a browser/form/ajax request directly to a PHP file in your plugin? – Tom J Nowell ♦ Commented Aug 9, 2020 at 0:33
• I think I might be... should the ajax function be on the theme function file? Not quite understanding the question. – petebolduc Commented Aug 9, 2020 at 0:38
• No it shouldn't, you can't make requests directly to PHP files in themes and plugins, be that via AJAX or another way. It won't work as WP won't be loaded. For AJAX use the REST API to register an endpoint so you have a URL to make requests to, look up register_rest_route – Tom J Nowell ♦ Commented Aug 9, 2020 at 0:42

1 Answer 1

It's failing because WordPress isn't loaded. Instead of making AJAX requests directly to PHP files in your theme, make them to a REST API endpoint.

For example:

add_action( 'rest_api_init', function () {
        register_rest_route( 'petebolduc/v1', '/test/', array(
                'callback' => 'petebolduc_ajax'
        ) );
} );
function petebolduc( $parameters ) {
    $foo = $parameters['foo'];
    return "foo is " . $foo;
}

With that code, visiting: example/wp-json/petebolduc/v1/test?foo=bar

gives:

"foo is bar"