MarshallingView does not support JAXBElement value by default [SPR-11827]

[spring-projects-issues]

Stephen Medders opened SPR-11827 and commented

The method locateToBeMarshalled in org.springframework.web.servlet.view.xml.MarshallingView checks to see if the object from the model is supported by the marshaller, and throws an exception if it is not:

if (!this.marshaller.supports(obj.getClass())) {
    throw new IllegalStateException("Model object [" + obj + "] retrieved via key [" +
this.modelKey + "] is not supported by the Marshaller");
}

In some circumstances, a service may need to marshal an object that requires wrapping in a JAXBElement before marshalling. In this case, the obj variable will be of class JAXBElement. Calls to marshaller.supports(obj) when obj is a JAXBElement always returns false, at least for the Spring Jaxb2Marshaller. An additional check should be added so that if obj is a JAXBElement, then check if the marshaller supports the class of that elements value:

this.marshaller.supports(jaxbElement.getDeclaredType());

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Affects: 4.0.5

Referenced from: commits e4aabd5

[spring-projects-issues]

Juergen Hoeller commented

Note that MarshallingView has a "supportJaxbElementClass" property which can be switched to "true" in order to generally accept JAXBElement in "supports(Class)" calls - designed exactly for such scenarios as with MarshallingView where we only have a Class to check, not a richer generic Type.

That said, you've got a point that MarshallingView could detect this and use the JAXBElement's declared type instead... at the expense of JAXB-specific code in MarshallingView. Alternatively, we could relax that "supports(Class)" check or let the "supportJaxbElementClass" property default to "true". I'll have a look at what we can do there.

Juergen

[spring-projects-issues]

Juergen Hoeller commented

I eventually opted for adding a JAXBElement-specific check to MarshallingView, since we're depending on JDK 6+ now anyway and therefore have JAXB 2.0's JAXBElement always present in the classpath.

Juergen