Question

I have read through the majority of posts on StackOverflow concerning this issue, and have tried numerous fixes, with nothing ultimately solving my problem. Spring throws an HttpMediaTypeNotSupportedException: Content type 'application/json' not supported

I have a controller that is defined like so:

 @RequestMapping(method = RequestMethod.POST, value = "/update")
 public @ResponseBody JSONDomainResponse update(@RequestBody Model inModel)

Where the model looks like so:

public class Model implements Serializable {

private static final long serialVersionUID = 2738522159847487651L;
private String id;
private BigDecimal offset;

@JsonCreator
public Model(@JsonProperty("id") String id, @JsonProperty("offset") BigDecimal offset) {
  this.id = id;
  this.offset = offset;
}

public String getID() {
  return id;
}

public BigDecimal getOffset() {
  return offset;
}

public void setID(String id) {
  this.id = id;
}

public void setOffset(BigDecimal offset) {
  this.offset = offset;
}
}

The AJAX call I am attempting to use looks like this:

$.ajax({
  type : 'POST',
  url : '/update',
  contentType : "application/json",
  data : JSON.stringify({"id":"test", "offset":300})
 });

I have the <mvc:annotation-driven/> configuration in my context.xml file, and I have verified that MappingJacksonHttpMessageConverter‘s canRead() method returns true for my model and the JSON Media Type.

I do also have the Jackson core and mapper jars specified in my classpath.

I have noticed that removing the Model parameter from the controller signature makes it so I actually reach the controller with my post, which leads me to believe there is some problem with my Model. Since there is minimal information logged, however, I can’t really tell what the problem can be.

Thanks in advance.

Answer 1

I finally found the solution to the problem, which was trivial but entirely non-obvious.

It turns out the Model object I was attempting to deserialize was in an improperly named package, and when Spring was unable to locate the Model, it simply swallows the generated exception and returns false. I discovered this through debugging deep in Spring-MVC land, particularly the StdDeserializerProvider class.

For others out there receiving this error, I would highly recommend writing some code to verify what is happening in this class, for example:

@Test
public void testThatCanConvertUpdateModel() {
  MappingJacksonHttpMessageConverter conv = new MappingJacksonHttpMessageConverter();
  assertTrue(conv.canRead(YourModel.class, MediaType.APPLICATION_JSON));
}