Interceptors

An Interceptor is a Lifecycle Component that can be used to modify the request or response before or after the request is processed by the controller or endpoint.

Interceptors are useful for binding data to the request context, transforming the request or response, and other tasks that need to be executed before or after the endpoint.

Execution#

Interceptors are executed in two phases:

Pre#

The pre method is executed after the Guards and before the endpoint.

Post#

The post method is executed after the endpoint and before the response is returned.

Order of Execution#

Interceptors are executed in the order they are registered. Before the endpoint is executed, all pre-interceptors are executed. After the endpoint is executed, all post-interceptors are executed in the reverse order.

1. Interceptor 1 (pre)
2. Interceptor 2 (pre)
3. Endpoint
4. Interceptor 2 (post)
5. Interceptor 1 (post)

Create an Interceptor#

To create an Interceptor, you need to implement the Interceptor class and implement the pre and post methods.

import 'package:revali_router/revali_router.dart';

class MyInterceptor implements Interceptor {
    const MyInterceptor();

    @override
    Future<void> pre(context) async {}

    @override
    Future<void> post(context) async {}
}

Register the Interceptor#

To register the Interceptor, annotate your Interceptor class on the app, controller, or endpoint level.

import 'package:revali_router/revali_router.dart';

// highlight-next-line
@MyInterceptor()
@Get('')
Future<void> myEndpoint() {
    ...
}

Register as Type Reference#

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

import 'package:revali_router/revali_router.dart';

// highlight-next-line
@Intercepts([MyInterceptor])
@Get('')
Future<void> myEndpoint() {
    ...
}