Question

I’m using Jersey’s integrated Jackson processing to transform incoming JSON to a POJO, e.g.:

@POST
@Consumes(MediaType.APPLICATION_JSON)
public Response newCustomer( CustomerRepresentation customer)
{
...
}

If a client sends JSON with invalid fields Jersey currently returns a 500 Internal Server Error. Instead, I’d like to return a 400 Bad Request, preferably with some meaningful detail indicating which fields are in error.

Any insight into how this could be accomplished? (At least returning a generic 400 instead of the completely inappropriate 500?)

Update:
Here’s the exception being generated server-side, before my handler is invoked:

javax.servlet.ServletException: org.codehaus.jackson.map.exc.UnrecognizedPropertyException: 
Unrecognized field "this_isnt_a_known"_field" (Class com.redacted....), not marked as ignorable

Answer 1

I was finally able to work around this problem by implementing an ExceptionMapper to catch the UnrecognizedPropertyException thrown by Jackson and map it to a 400 Bad Request response:

@Provider
public class UnrecognizedPropertyExceptionMapper implements ExceptionMapper<UnrecognizedPropertyException>
{

    @Override
    public Response toResponse(UnrecognizedPropertyException exception)
    {
        return Response
                .status(Response.Status.BAD_REQUEST)
                .entity( "'" + exception.getUnrecognizedPropertyName() + "' is an unrecognized field.")
                .type( MediaType.TEXT_PLAIN)
                .build();
    }

}