When a @RequestMapping Returns a Sublclass of ResponseEntity It Is Returning Header and StatusCode Along with the Body [SPR-10046]

[spring-projects-issues]

Julian Builes opened SPR-10046 and commented

When subclassing ResponseEntity that returns a JSON response, the body in the resulting response is also including 'headers' and 'statusCode fields.

        class MyClass {      
            public String field;            
            public MyClass(String field1) {
                this.field = field1;
            }
        }
        
        class MyClassResponse extends ResponseEntity<MyClass> {
            public MyClassResponse(MyClass body, HttpHeaders headers, HttpStatus statusCode) {
                super(body, headers, statusCode);
            }
        }
        
        @RequestMapping(value = "aaa", method = RequestMethod.POST, consumes = MediaType.APPLICATION_JSON_VALUE)
        @ResponseBody
        public ResponseEntity<MyClass> dummy() {

            HttpHeaders headers = new HttpHeaders();
            headers.add("some-header", "some header value");
            headers.add("another-header", "another header value");

            return new MyClassResponse(new MyClass("this is the response body"), headers, HttpStatus.CREATED);
        }

Is returning:

{
"headers": {
"some-header": [(1)
"some header value"
],-
"another-header": [(1)
"another header value"
]-
},-
"body": {
"field": "this is the response body"
},-
"statusCode": "CREATED"
}

Considerations:

• This appears to be a regression introduced between 3.1.2 and 3.1.3.
• We are using Jackson to convert the JSON

---

Affects: 3.1.3

1 votes, 4 watchers

[spring-projects-issues]

Rossen Stoyanchev commented

You don't need @ResponseBody when returning ResponseEntity. Just remove the annotation and it should work.

[spring-projects-issues]

Julian Builes commented

Rosen, I am not sure if I am missing something trivial here, but if I remove the @ResponseBody, I receive the following exception:

javax.servlet.ServletException: Could not resolve view with name '<some path>' in servlet with name '<servlet name>'.

[spring-projects-issues]

Rossen Stoyanchev commented

@ResponseBody instructs Spring MVC to write the returned value to the response. ResponseEntity is a special return value that provides Spring MVC with all the information it needs to prepare the response -- body, headers, status. When you put @ResponseBody on a method that returns ResponseEntity, the former takes precedence and leads to unwanted results. What may have changed in 3.1.3 is the order in which these two are looked at. Regardless, it was never intended to have both at the same time. Here are some examples from the spring-mvc-showcase.

[spring-projects-issues]

Shelley J. Baker commented

This doesn't work for ResponseEntity subclasses, though. In particular, the HttpEntityMethodProcessor's supportsReturnType method explicitly looks for ResponseEntity/HttpEntity classes, not whether they are assignable from those classes:

public boolean supportsReturnType(MethodParameter returnType) {
	Class<?> parameterType = returnType.getParameterType();
	return HttpEntity.class.equals(parameterType) || ResponseEntity.class.equals(parameterType);
}

Changing this method to the following seems to do the trick:

public boolean supportsReturnType(MethodParameter returnType) {
    Class<?> parameterType = returnType.getParameterType();
    return HttpEntity.class.isAssignableFrom(parameterType);
}

(Or as a temporary workround, you can add a custom HandlerMethodReturnValueHandler which overrides this method.)

[spring-projects-issues]

Rossen Stoyanchev commented

I think it'd be best to open a new issue. The original description here mixes @ResponseBody with ResponseEntity, which is not a valid combination. Your last comment is a legitimate issue. Thanks!

[spring-projects-issues]

Shelley J. Baker commented

#14840 has been logged for this issue.