Observer

The Observer component is a Lifecycle Component that can be used to observe the request and response before or after the request is processed. Regardless of the request flow's result, the observer is executed. Meaning that even if the request is rejected by a guard or an exception is thrown, the observer will still be executed.

Observers are unique in that they can only be registered at the app level. This means that all requests will be observed by the observer.

Observers are useful for logging, monitoring, and other tasks that need to be executed before or after the request.

Execution#

Observers are executed immediately after the request is received and before the response is returned to the client.

Create an Observer#

To create an Observer, you need to implement the Observer class and implement the see method.

import 'package:revali_router/revali_router.dart';

class MyObserver implements Observer {
    const MyObserver();

    @override
    Future<void> see(request, response) async {}
}

Register the Observer#

To register the Observer, annotate your Observer class on the app level.

import 'package:revali_router/revali_router.dart';

// highlight-next-line
@MyObserver()
@App()
class MyApp ...

Register as Type Reference#

If you have a parameter that can not be provided at compile time, you can register the Observer as a type reference using the @Observers() annotation.

import 'package:revali_router/revali_router.dart';

// highlight-next-line
@Observers([MyObserver])
@App()
class MyApp ...