Overloading SpringBoot #PostMapping controller method not working - spring-boot

Question

I have faced some challenge and to describe shortly I created test application. Code you can see and error you can see below.
#RestController
public class TestController {
#PostMapping(value = "/test",params = { "a", "b" })
public String test(#RequestPart MultipartFile a, #RequestPart(required = false) MultipartFile b) {
return "test1";
}
#PostMapping(value = "/test", params = { "b" })
public String test(#RequestPart MultipartFile b) {
return "test2";
}
}
I`m trying to execute this request from postman:
And I`m getting such error in logs:
Resolved [org.springframework.web.bind.UnsatisfiedServletRequestParameterException:
Parameter conditions "a, b" OR "b" not met for actual request parameters: ]
The thing is, if I will put parameters also in postman (not in body, in request url: localhost:8080/test?b=anything) it will work fine, but I don`t need request params in url.
Is there some possible way to make it work?

Answer 1

I am able to override #PostMapping. But the type of the parameter should be different.
#PostMapping(value="/test" )
public String testApi(#ModelAttribute MultipartDTO multipartDTO) {
return "test1";
}
#PostMapping(value="/test" ,params = { "b" })
public String test(#RequestParam String b) {
return "test2";
}
/** DTO **/
#Data
public class MultipartDTO{
private MultipartFile a;
private MultipartFile b;
}

Answer 2

you can not map the same signature twice which contains the same Http methods then below error will occur.
java.lang.IllegalStateException: Ambiguous handler methods
try this one
#RestController
public class TestController {
#PostMapping("/test")
public String test(#RequestParam MultipartFile a, #RequestParam(required = false) MultipartFile b) {
return "test1";
}
#PostMapping("/test2")
public String test(#RequestParam MultipartFile b) {
return "test2";
}
}

Answer 3

You should try something like below.
#RestController
public class TestController {
#PostMapping(value = "/test")
public String test(#RequestParam MultipartFile a, #RequestParam(required = false) MultipartFile b) {
return "test1";
}
#PostMapping(value = "/test")
public String test(#RequestParam MultipartFile b) {
return "test2";
}
}