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How can I add custom fields to the WordPress REST API response?

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How can I add custom fields to the WordPress REST API response?

Asked on Mar 01, 2026

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To add custom fields to the WordPress REST API response, you can use the `register_rest_field` function. This function allows you to register a new field for a specific post type, which will then be included in the API response.

<!-- BEGIN COPY / PASTE -->
    function add_custom_fields_to_rest_api() {
        register_rest_field('post', 'custom_field', array(
            'get_callback' => function($post_arr) {
                return get_post_meta($post_arr['id'], 'custom_field', true);
            },
            'update_callback' => null,
            'schema' => null,
        ));
    }
    add_action('rest_api_init', 'add_custom_fields_to_rest_api');
    <!-- END COPY / PASTE -->

Additional Comment:

The `register_rest_field` function is used to add custom fields to the REST API response for a specific post type, such as 'post'.
The `get_callback` function retrieves the custom field value using `get_post_meta`.
Ensure that the custom field key ('custom_field' in this example) matches the meta key used in your WordPress database.
This code should be added to your theme's `functions.php` file or a custom plugin.

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Ask any question about WordPress here... and get an instant response.

How can I add custom fields to the WordPress REST API response?

Asked on Mar 01, 2026

Answer

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