Better exception message for missing @RequestBody method parameter [SPR-12888]

[spring-projects-issues]

Martin Meyer opened SPR-12888 and commented

When I use @RequestBody on one of my controllers for a required parameter, I need some useful way of saying which parameter was missing if it's not there. The exception message I see currently looks like this:

Required request body content is missing: org.springframework.web.method.HandlerMethod$HandlerMethodParameter@a8b8886e
	at org.springframework.test.util.MatcherAssertionErrors.assertThat(MatcherAssertionErrors.java:80)
	at org.springframework.test.util.JsonPathExpectationsHelper.assertValue(JsonPathExpectationsHelper.java:92)
	at org.springframework.test.web.servlet.result.JsonPathResultMatchers$1.match(JsonPathResultMatchers.java:56)
	at org.springframework.test.web.servlet.MockMvc$1.andExpect(MockMvc.java:152)
...

It would be nice if when that exception could have a reference to the parameter name that was missing, or if the message itself included it instead of the MethodParameter#toString(). I'll eventually want to internationalize the message I produce, so the parameter name is preferable.

---

Affects: 4.1.3

Referenced from: commits 13403d5

[spring-projects-issues]

Rossen Stoyanchev commented

The HttpMessageNotReadableException can be raised from many places where a method parameter does not apply so adding a new field to the exception isn't ideal. I considered sub-classing the exception but what I've done instead is to print the full method signature to improve the error message. Also we now support injecting the selected HandlerMethod into an @ExceptionHandler method so you can obtain the full information on the @RequestMapping method we were trying to call.

[spring-projects-issues]

Rossen Stoyanchev commented

Resolving for now but feel free to comment further.