WP_REST_Server::dispatch() WordPress Method

	public function dispatch( $request ) {
		/**
		 * Filters the pre-calculated result of a REST API dispatch request.
		 *
		 * Allow hijacking the request before dispatching by returning a non-empty. The returned value
		 * will be used to serve the request instead.
		 *
		 * @since 4.4.0
		 *
		 * @param mixed           $result  Response to replace the requested version with. Can be anything
		 *                                 a normal endpoint can return, or null to not hijack the request.
		 * @param WP_REST_Server  $server  Server instance.
		 * @param WP_REST_Request $request Request used to generate the response.
		 */
		$result = apply_filters( 'rest_pre_dispatch', null, $this, $request );

		if ( ! empty( $result ) ) {
			return $result;
		}

		$error   = null;
		$matched = $this->match_request_to_handler( $request );

		if ( is_wp_error( $matched ) ) {
			return $this->error_to_response( $matched );
		}

		list( $route, $handler ) = $matched;

		if ( ! is_callable( $handler['callback'] ) ) {
			$error = new WP_Error(
				'rest_invalid_handler',
				__( 'The handler for the route is invalid.' ),
				array( 'status' => 500 )
			);
		}

		if ( ! is_wp_error( $error ) ) {
			$check_required = $request->has_valid_params();
			if ( is_wp_error( $check_required ) ) {
				$error = $check_required;
			} else {
				$check_sanitized = $request->sanitize_params();
				if ( is_wp_error( $check_sanitized ) ) {
					$error = $check_sanitized;
				}
			}
		}

		return $this->respond_to_request( $request, $route, $handler, $error );
	}