Clarify the single class restriction with @JsonView for a response body advice [SPR-12270]

[spring-projects-issues]

Alexey Krylov opened SPR-12270 and commented

Currently only one @JsonView class is used:

JsonViewResponseBodyAdvice.java:

	@Override
	protected void beforeBodyWriteInternal(MappingJacksonValue bodyContainer, MediaType contentType,
			MethodParameter returnType, ServerHttpRequest request, ServerHttpResponse response) {

		JsonView annotation = returnType.getMethodAnnotation(JsonView.class);
		Assert.isTrue(annotation.value().length != 0, "No view class in JsonView annotation on " + returnType);
		bodyContainer.setSerializationView(annotation.value()[0]);
	}

My code:

@JsonView({Category.Default.class, Product.Default.class})
   @RequestMapping("/catalog.json")
   public Collection<Category> getCatalog(@Named("deviceId") @RequestParam(value = "device_id", required = false) Integer deviceId) {
       return retrieveCatalog(deviceId);
   }

In this example only Category.Default.class will be used.
It will be very nice to have full support for @JsonView.

---

Affects: 4.1 GA

Referenced from: commits a3fd00e, ae43b17

[spring-projects-issues]

Sébastien Deleuze commented

Hi Alexey,

@JsonView was originally created to annotate a field with one or multiple views, but like JAX-RS @JsonView support (more details at http://wiki.fasterxml.com/JacksonJsonViews), we are reusing this annotation in Spring MVC for another purpose: enabling a view on a per handler method basis, and in this context Jackson API does not support multiple views.

I am going to add a check in order to actively reject multiple view classes in this context, and update our documentation accordingly.

For your need, you should use a single view interface that will inherit of multiple other ones. Jackson will use the view specified and all the inherited ones to serialize the output.

Please also notice that we are going to change the default configuration in the upcoming 4.1.1 release when using @EnableWebMvc or <mvc:annotation-driven />. By default, SerializationConfig.Feature.DEFAULT_VIEW_INCLUSION will be set to false in order to avoid including non annotated fields/properties in the output when @JsonView is used on a method handler. See #16793 for more details.

Regards,
Sébastien Deleuze

[spring-projects-issues]

Alexey Krylov commented

Hi Sebastien,
Will try this approach with one composite interface.
Thanks.

[spring-projects-issues]

Alexey Krylov commented

Yes, it works!
Thanks!

public interface NativeClient extends Category.WithProductsCount, Product.WithSections, Product.WithoutDescription {
}
...

@JsonView(NativeClient.class)

[spring-projects-issues]

Juergen Hoeller commented

Sébastien Deleuze, I've revised JsonViewResponseBodyAdvice's assertion to insist on exactly 1 class specified there. Let's mark this issue as resolved once we've also documented that as discussed on the team call today.

Juergen