Interceptor class - chopper library

The interface for implementing interceptors. Interceptors are used for intercepting request, responses and preforming operations on them.

Interceptor are called in a Chain order. The first interceptor in the chain calls the next interceptor in the chain and so on. The last interceptor in the chain return the response back to the previous interceptor in the chain and so on. This means the request are processed in the order defined by the chain. The responses are process in the reverse order defined by the chain.

Chopper has a few built-in interceptors which can be inspected as fully working examples: HttpLoggingInterceptor, CurlInterceptor and HeaderInterceptor.

A short example for adding an authentication token to every request:

class MyRequestInterceptor implements Interceptor {
  final String token;

  @override
  FutureOr<Response<BodyType>> intercept<BodyType>(Chain<BodyType> chain) async {
    final request = applyHeader(chain.request, 'auth_token', 'Bearer $token');
    return chain.proceed(request);
  }
}

A short example for extracting a header value from a response:

class MyResponseInterceptor implements Interceptor {
  String _token;

  @override
  FutureOr<Response<BodyType>> intercept<BodyType>(Chain<BodyType> chain) async {
    final response = await chain.proceed(chain.request);

    _token = response.headers['auth_token'];
    return response;
  }
}

While Interceptors can modify the body of requests and responses, converting (encoding) the request/response body should be handled by Converters.

Interceptor class abstract interface

Constructors

Properties

Methods

Operators

chopper library