I registered a custom post type called wasb_message with show_in_rest set to true and rest_base set to 'messages' so the resource is reachable at endpoint https://mydomain/wp-json/wp/v2/messages (using the WP_REST_Posts_Controller class). The custom post type has a custom meta field called wasb_status with an integer value, how can I add a custom parameter so when I do a get request to endpoint https://mydomain/wp-json/wp/v2/messages?status=2 I retrieve messages with wasb_status equal to 2 without register a new route?

I read this code reference page and this old question but I can't get it working, using Postman to send get request I get:

    "code": "rest_invalid_param",
    "message": "Parametro(i) non valido(i): status",
    "data": {
        "status": 400,
        "params": {
            "status": "Stato non consentito."
        "details": {
            "status": {
                "code": "rest_forbidden_status",
                "message": "Stato non consentito.",
                "data": {
                    "status": 401

2 Answers 2


I solved following this answer and writing:

public function query_wasb_messages_by_status( $args, $request ) {

        if ( ! is_null( $request->get_param( 'message_status' ) ) ) {
            $args['meta_query'] = array(
                '_wasb_message_status' => array(
                    'key'     => '_wasb_message_status',
                    'value'   => (int) $request->get_param( 'message_status' ),
                    'compare' => '=',
                    'type'    => 'numeric'

        return $args;

add_filter( 'rest_wasb_message_query', array( $this, 'query_wasb_messages_by_status'), 10, 2 );

My problem is I used status as parameter name but status already exists for posts ('draft', 'published', etc...) so I changed the name to message_status...


As per the reply by Haris it should be something like this:

function wasb_rest_parameter($args, $request) {
    if( isset($request["wasb_status"]) && is_numeric($request["wasb_status"]) ) {
        $args['meta_key'] = 'wasb_status';
        $args['meta_value'] = intval($request["wasb_status"]);
    return $args;
add_filter('rest_wasb_message_query', 'wasb_rest_parameter', 10, 2);

Not yet tested. If it does not work, will update the answer.

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