Multiple converters with Retrofit 2

Question

I have a HATEOAS (HAL) REST service and managed to talk to it with the code below (using halarious as a conversion engine) but when I try to merge the converters (stal

Answer 1

You need to return null from the Converter.Factory if the type does not match. Keep the Class around in a field to compare it against.

@Override
public Converter fromResponseBody(Type type, Annotation[] annotations) {
  if (!this.type.equals(type)) {
    return null;
  }
  return new HALResponseBodyConverter<>(gson);
}

This will allow multiple instances to be used because each only applies to its own type.

That said, however, you can probably get away with only using a single converter and pulling the class from the Type that is passed in.

@Override
public Converter fromResponseBody(Type type, Annotation[] annotations) {
  if (!HALResponse.class.isAssignableFrom(type)) {
    return null;
  }
  // TODO create converter with `type` now that you know what it is...
}

You can look at the Wire converter in the repo which does this for a full example.