Spring Validator annotation is not working

Question

In my request body I am passing parameter in different way to validate.

{ 
  "name":[]
}

Here the operation is executing which I want to restrict with my custom error message.

Here I am getting 400 bad request so how to handle this with proper error message.

In my controller I had

if (myRequestResult.getName() == null || myRequestResult.getName().isEmpty()) {
    throw new Exception();
 } else {
    myService.setName(myRequestResult.getName());
 }

Which is working fine but Now I remove that and Using validator annotation.

@Data 
public class MyResultRequest {
  
  @NotEmpty(message = "List of name must not be empty")
  @Size(min = 1, message = "List of name must have at least one element")
  private List<String> name;

}

This is my restcontroller

@Log4j2
@RestController(value = "apiMyController")
@RequestMapping(path = "/api/v1/someRandomeURL")
@RequiredArgsConstructor(onConstructor = @__({@Autowired}))
public class ExecutionResultsController {
  
  @RequestMapping(method = RequestMethod.POST)
  public ExecutionResultDTO create(@RequestBody  MyRequestResult myRequestResult) throws Exception {
     myService.setName(myRequestResult.getName());
  }
}  

Can anybody tell me how to fix that as I am following this from here Doc

Answer 1

@seenukarthi is actually correct. You have to use @Valid on the endpoint to valid the request body.

Note: The validation errors are not visible in the error response.

The error will appear in the console log. Example:

2023-11-20T13:12:13.057+05:30  WARN 85261 --- [nio-8081-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.bind.MethodArgumentNotValidException: Validation failed for argument [0] in public org.springframework.http.ResponseEntity<java.lang.Object> com.example.TestController.create(com.example.MyRequestResult) with 2 errors: [Field error in object 'myRequestResult' on field 'name': rejected value [[]]; codes [NotEmpty.model.name,NotEmpty.name,NotEmpty.java.util.List,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [model.name,name]; arguments []; default message [name]]; default message [List of name must not be empty]] [Field error in object 'model' on field 'name': rejected value [[]]; codes [Size.model.name,Size.name,Size.java.util.List,Size]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [model.name,name]; arguments []; default message [name],2147483647,1]; default message [List of name must have at least one element]] ]

Please look into the logs properly. It will be there.

---

Now, if you want to capture validation errors happened on request body and to include it to response, then you have to use org.springframework.validation.BindingResult.

Let me show with an example:

Update ExecutionResultDTO to have errors list also if possible :

@Data
public class ExecutionResultDTO {

    private List<String> name;

    private List<String> errors;

}

Updated controller that I have used for testing:

import jakarta.validation.Valid;
import org.springframework.context.support.DefaultMessageSourceResolvable;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.*;

@RestController
public class TestController {

    @PostMapping("create")
    public ResponseEntity<ExecutionResultDTO> create(@Valid @RequestBody MyRequestResult myRequestResult, BindingResult bindingResult) {
        ExecutionResultDTO dto = new ExecutionResultDTO();
        dto.setName(myRequestResult.getName());
        if (bindingResult.hasErrors()) {
            dto.setErrors(bindingResult.getFieldErrors().stream()
                    .map(DefaultMessageSourceResolvable::getDefaultMessage).collect(Collectors.toList()));
            return new ResponseEntity<>(dto, HttpStatus.BAD_REQUEST);
        }
        return new ResponseEntity<>(dto, HttpStatus.CREATED);
    }
}

Postman :

For Incorrect Data:

For Correct Data:

Change the logic accordingly. This is just an example.