Create a Custom API Endpoint in WordPress

Creating a custom endpoint in WordPress to check for plugin updates involves several steps. This process includes setting up a custom REST API endpoint, creating a function to handle requests to this endpoint, and ensuring that the response contains the necessary information about the plugin updates. Here’s a step-by-step guide:

1. Register a Custom REST API Endpoint

You need to register a custom endpoint in WordPress's REST API. This can be done by using the register_rest_route function.

Add the following code to your plugin or theme's functions.php file:

add_action('rest_api_init', function () {
    register_rest_route('custom/v1', '/plugin-updates/', array(
        'methods' => 'GET',
        'callback' => 'check_for_plugin_updates',
    ));
});

2. Create the Callback Function

Next, you need to create the callback function check_for_plugin_updates that will handle the request to your custom endpoint. This function will check for updates and return the relevant information.

Here’s an example of what the callback function might look like:

function check_for_plugin_updates() {
    // Define the plugin slug and the current version
    $plugin_slug = 'your-plugin-slug';
    $current_version = '1.0.0';

    // Simulate checking for updates (you would normally fetch this data from your server)
    $response = array(
        'new_version' => '1.1.0',
        'package' => 'https://example.com/path/to/your-plugin.zip',
        'slug' => $plugin_slug,
        'requires' => '5.0',
        'tested' => '5.7',
        'last_updated' => '2024-05-30',
        'sections' => array(
            'description' => 'This is the update description.',
            'installation' => 'Installation instructions here.',
            'changelog' => 'Changelog content here.',
        ),
    );

    // Check if there is an update
    if (version_compare($current_version, $response['new_version'], '<')) {
        return new WP_REST_Response($response, 200);
    } else {
        return new WP_REST_Response(array('message' => 'No updates available'), 200);
    }
}

3. Secure Your Endpoint

To ensure that only authorized requests can access your update information, you might want to secure your endpoint. You can do this by adding a permission callback function:

add_action('rest_api_init', function () {
    register_rest_route('custom/v1', '/plugin-updates/', array(
        'methods' => 'GET',
        'callback' => 'check_for_plugin_updates',
        'permission_callback' => function () {
            return current_user_can('manage_options'); // Adjust capability as needed
        },
    ));
});

4. Use the Custom Endpoint in Your Plugin

In your plugin's main file, you need to set up the plugin update mechanism to use the custom endpoint. Here’s an example of how you might do this:

add_filter('site_transient_update_plugins', 'check_custom_plugin_updates');

function check_custom_plugin_updates($transient) {
    if (empty($transient->checked)) {
        return $transient;
    }

    $plugin_slug = 'your-plugin-slug/your-plugin-file.php';
    $api_url = 'https://your-site.com/wp-json/custom/v1/plugin-updates/';

    $response = wp_remote_get($api_url);
    if (is_wp_error($response) || wp_remote_retrieve_response_code($response) !== 200) {
        return $transient;
    }

    $data = json_decode(wp_remote_retrieve_body($response));
    if (version_compare($transient->checked[$plugin_slug], $data->new_version, '<')) {
        $transient->response[$plugin_slug] = (object) array(
            'slug' => $data->slug,
            'new_version' => $data->new_version,
            'package' => $data->package,
            'url' => '',
        );
    }

    return $transient;
}

5. Testing the Endpoint

Ensure your custom endpoint is working by accessing it directly via a browser or a tool like curl or Postman:

https://your-site.com/wp-json/custom/v1/plugin-updates/

You should receive a JSON response with the plugin update information.

By following these steps, you can create a custom endpoint for WordPress to check for plugin updates, ensuring that your plugins can check for and receive updates from your custom source.