What is the purpose of elementClass parameter in ServerResponse.BodyBuilder?

Question

There's a simple model class, which is supposed to be used for response body serialization:

public class MyModel{
  public String name;
}

Using it in an arbitrary Spring 5 handler function:

public Mono getSometing(ServerRequest request) {
  MyModel model = new MyModel();
  model.name = "abc";

  return ServerResponse.ok().body(Mono.just(model), %anyClass%);
}

I tried to substitute for %anyClass% different classes: Object, String, MyModel, RuntimeException - and the result is always the same. Every time the model instance had been serialized to a json {"name" : "abc"}.

It also works for more complex models with nested objects and arrays.

Could you comment, what is the purpose of the second parameter (elementClass ) if it does not affect the result? Why cannot we use Object.class always?

user_8287251 · Answer

Its not anyclass, its generally the type of class you want to publish/produce. In your case Its can be the MyModel.class, the one you are sending in the response.

If you read the spring documentation, it will make more sense to you. https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/reactive/function/server/ServerResponse.BodyBuilder.html

You can update the last line of your code : ServerResponse.ok().body(Mono.just(model), MyModel.class)

What is the purpose of elementClass parameter in ServerResponse.BodyBuilder?

1 Answers