How to use selected WordPress functions?

I have a custom PHP file on which I want to use some WordPress functions such as wp_get_current_user(). I've tried requiring wp-load.php, but that increases the load time significantly as it loads all WP functions.

Is there anyway I can use only the functions I need from WP?

Thanks, Emir

I have a custom PHP file on which I want to use some WordPress functions such as wp_get_current_user(). I've tried requiring wp-load.php, but that increases the load time significantly as it loads all WP functions.

Is there anyway I can use only the functions I need from WP?

Thanks, Emir

• functions

Share Improve this question asked Feb 4, 2019 at 12:13 MirekoMireko 1111 silver badge22 bronze badges 3

• Writing your own version of the function is the obvious way but I assume you've already thought of that. It is likely that other WP environment vars will be needed but unavailable if WordPress is not running. – jdm2112 Commented Feb 4, 2019 at 16:04
• Hi jdm2112, thanks for your comment. I haven't thought of creating my own version of the function. How would you do that? – Mireko Commented Feb 4, 2019 at 17:25
• Find the code you want to use and copy it to your codebase. Prefix the function name to avoid collisions, etc. Depending on the function you are wanting to call there are likely to be specific WP environment values missing, however, such as $post, $wp_query and others. – jdm2112 Commented Feb 4, 2019 at 21:04

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2 Answers 2

Sorted by: Reset to default 2

You may be able to have Wordpress push data to the session or to your custom PHP, rather than trying to load Wordpress each time you need to query some the user. I'm not sure what other functions you want to call.

The alternative is to use the Wordpress REST API, take a look at the authentication section.

Short answer

No.

Slightly Longer Answer

Most WordPress methods require a working WordPress backend to run. Let's take a look at wp_get_current_user as an example:

function wp_get_current_user() {
    return _wp_get_current_user();
}

Which leads us to _wp_get_current_user:

function _wp_get_current_user() {
    global $current_user;

    if ( ! empty( $current_user ) ) {
        if ( $current_user instanceof WP_User ) {
            return $current_user;
        }

        // Upgrade stdClass to WP_User
        if ( is_object( $current_user ) && isset( $current_user->ID ) ) {
            $cur_id = $current_user->ID;
            $current_user = null;
            wp_set_current_user( $cur_id );
            return $current_user;
        }

        // $current_user has a junk value. Force to WP_User with ID 0.
        $current_user = null;
        wp_set_current_user( 0 );
        return $current_user;
    }

    if ( defined('XMLRPC_REQUEST') && XMLRPC_REQUEST ) {
        wp_set_current_user( 0 );
        return $current_user;
    }

    /**
     * Filters the current user.
     *
     * The default filters use this to determine the current user from the
     * request's cookies, if available.
     *
     * Returning a value of false will effectively short-circuit setting
     * the current user.
     *
     * @since 3.9.0
     *
     * @param int|bool $user_id User ID if one has been determined, false otherwise.
     */
    $user_id = apply_filters( 'determine_current_user', false );
    if ( ! $user_id ) {
        wp_set_current_user( 0 );
        return $current_user;
    }

    wp_set_current_user( $user_id );

    return $current_user;
}

We can see that WordPress does a lot "under the hood" to get the current user, so implementing this function as a standalone method probably wouldn't get you too far.

Alternatives

As suggested in the other answer by @AlexanderHolsgrove, the REST API is a good way to communicate to a WordPress install if you need to fetch/send data to WordPress from another application.

You should also take a look at the SHORTINIT constant - if defined in your wp-config.php, it loads certain parts of WordPress and then bails out. I'm not sure if it would load what you need, but it may be worth taking a look there.