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  1. Spring Framework
  2. SPR-15461

Add body(Object) method to ServerResponse.BodyBuilder



    • Type: Improvement
    • Status: Closed
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 5.0 RC1
    • Component/s: Reactive, Web
    • Labels:
    • Last commented by a User:


      We should add a ServerResponse.BodyBuilder.body(Object) method, to make it easier for users to set the response body to a non-Publisher type. Currently, this task can be accomplished via body(BodyInserters.fromObject(Object)), but because this method requires a static import of BodyInserters, the discoverability of it is not as high as body(Publisher, Class)). As such, users will go this route:

      return ServerResponse.ok().body(Mono.just("Hello World"), String.class);

      instead of the more elegant:

      return ServerResponse.ok().body(fromObject("Hello World"));

      However, adding the method has a serious consequence: there is the potential for accidental method overloading between a the new Object method and the existing Publisher body method. As a result, users will accidentally write a response with the publisher itself, rather than its contents:

      Flux<String> flux = ...
      return ServerResponse.ok().body(flux); // Whoops, should have been body(flux, String.class);

      Of course, we cannot automatically call the correct method, because of the lacking Class argument. There are, however, a couple of other ways we can resolve this.

      1. Give the method a different name, such as bodyFromObject. If we go this route, we should be consistent and also rename the existing Publisher-based body method to bodyFromPublisher. As such, it has serious consequences for the brevity and UX of the API.
      2. Perform a runtime-check to see whether the Object passed to body is a Publisher, and throw an exception if so, warning the user of the error of their ways.
      3. Do not add the method. Since this a Reactive web framework, the case can be made that returning non-reactive types as a response is not a main design goal. Returning a String makes for a great demo, but might not be as necessary for real-life reactive scenarios.


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              arjen.poutsma Arjen Poutsma
              arjen.poutsma Arjen Poutsma
              Last updater:
              Spring Issues Spring Issues
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