[API] Một ví dụ về lọc dữ liệu validate (ok)

https://developer.wordpress.org/rest-api/extending-the-rest-api/routes-and-endpoints/

<?php
/**
 * This is our callback function that embeds our resource in a WP_REST_Response
 */
function prefix_get_colors($request) {
  // In practice this function would fetch more practical data. Here we are just making stuff up.
  $colors = array(
    'blue',
    'blue',
    'red',
    'red',
    'green',
    'green',
  );
  if (isset($request['filter'])) {
    $filtered_colors = array();
    foreach ($colors as $color) {
      if ($request['filter'] === $color) {
        $filtered_colors[] = $color;
      }
    }
    return rest_ensure_response($filtered_colors);
  }
  return rest_ensure_response($colors);
}
/**
 * Validate a request argument based on details registered to the route.
 *
 * @param  mixed            $value   Value of the 'filter' argument.
 * @param  WP_REST_Request  $request The current request object.
 * @param  string           $param   Key of the parameter. In this case it is 'filter'.
 * @return WP_Error|boolean
 */
function prefix_filter_arg_validate_callback($value, $request, $param) {
  // If the 'filter' argument is not a string return an error.
  if (!is_string($value)) {
    return new WP_Error('rest_invalid_param', esc_html__('The filter argument must be a string.', 'my-text-domain'), array('status' => 400));
  }
  // Get the registered attributes for this endpoint request.
  $attributes = $request->get_attributes();
  // Grab the filter param schema.
  $args = $attributes['args'][$param];
  // If the filter param is not a value in our enum then we should return an error as well.
  if (!in_array($value, $args['enum'], true)) {
    return new WP_Error('rest_invalid_param', sprintf(__('%s is not one of %s'), $param, implode(', ', $args['enum'])), array('status' => 400));
  }
}
/**
 * We can use this function to contain our arguments for the example product endpoint.
 */
function prefix_get_color_arguments() {
  $args = array();
  // Here we are registering the schema for the filter argument.
  $args['filter'] = array(
    // description should be a human readable description of the argument.
    'description'       => esc_html__('The filter parameter is used to filter the collection of colors', 'my-text-domain'),
    // type specifies the type of data that the argument should be.
    'type'              => 'string',
    // enum specified what values filter can take on.
    'enum'              => array('red', 'green', 'blue'),
    // Here we register the validation callback for the filter argument.
    'validate_callback' => 'prefix_filter_arg_validate_callback',
  );
  return $args;
}
/**
 * This function is where we register our routes for our example endpoint.
 */
function prefix_register_example_routes() {
  // register_rest_route() handles more arguments but we are going to stick to the basics for now.
  register_rest_route('my-colors/v1', '/colors', array(
    // By using this constant we ensure that when the WP_REST_Server changes our readable endpoints will work as intended.
    'methods'  => WP_REST_Server::READABLE,
    // Here we register our callback. The callback is fired when this endpoint is matched by the WP_REST_Server class.
    'callback' => 'prefix_get_colors',
    // Here we register our permissions callback. The callback is fired before the main callback to check if the current user can access the endpoint.
    'args'     => prefix_get_color_arguments(),
  ));
}
add_action('rest_api_init', 'prefix_register_example_routes');
?>