Request Events

If you don't want to use the full power of the Hooks object, Serinus provides a way to listen to specific events of a request. Although not so specific as the Hooks object, the RequestEvents are a good way to listen to the most common events of a request and act accordingly.

To listen to request events, you just need to call the method on of the Request object. The method takes two arguments: the event name and a callback function. The most common case where the RequestEvents are useful is in Middlewares to log, or handle errors, or even to close resources when the request is closed.

import 'package:serinus/serinus.dart';

class RequestEventMiddleware extends Middleware {
  
  RequestEventMiddleware();

  @override
  Future<void> use(RequestContext context, NextFunction next) async {
    context.request.on(RequestEvent.close, (event, data) async {
      print("Request closed");
    });
    return next();
  }
}

The example above listens only to the RequestEvent.close event. The callback function will be called when the request is closed.

The following events are available:

Event Name	Description
RequestEvent.error	An error occurred during the request.
RequestEvent.redirect	The request is redirected.
RequestEvent.data	Data is received and sent to the response.
RequestEvent.close	The request is closed.
RequestEvent.all	All events.

The callback function receives two arguments: the event name and the data associated with the event. The data is of type EventData and contains the following properties:

• exception: The exception that occurred. (Only available for the RequestEvent.error event)
• data: The data received. (Available for all events except RequestEvent.redirect)
• properties: The properties of the response. (Available for all events)
• hasException: A boolean value that indicates if the event contains an error. (Available for all events)