WordPress REST API Custom Endpoint with URL Parameter

Question

I am trying to create a custom endpoint for the WordPress REST API and pass parameters through the URL.

The endpoint currently is:

/wp-json/v1/products

Answer 1

I modified the provided answer a little to get my desired endpoint:

/wp-json/api/v1/product?identifier=81838240219

add_action( 'rest_api_init', function () {
register_rest_route( 'api/v1', '/product/', array(
      'methods' => 'GET',
      'callback' => 'ea_get_product_data',
    ) );
} );

function ea_get_product_data( $data ) {
    $identifier = $data->get_param( 'identifier' );
    return $identifier;
}