Handle Custom Validations and Exceptions in REST with SpringBoot

Question

I am following this article API Error Handling (also please suggest if there is a better way to do this) to handle exceptions and validations in a generic way in my spring boot rest service. (i am new to spring and rest, so i am going through different articles for my requirement)

Basic idea about the requirement:

(Need to validate the POST request and send the validation errors to the client in a structure way. There could be multiple validation errors)

Whenever i get a POST request from my client, i need to validate the RequestBody. So I added @Valid on the parameter and @NotNull on the properties which i want to validate. Upon receiving the POST request spring is validating the request and throwing MethodArgumentNotValidException which is fine since i have some mandatory field missing. I am handling it in a common place with @ControllerAdvice. After hitting the appropriate method handleMethodArgumentNotValid(...), i am constructing my custom error response APICustomError which i following from the above mentioned article.

When i have multiple validation errors, i am able to loop all the errors and adding it to a list and constructing the ResponseEntity with my custom error. But the returned ResponseEntity does not have my added validation errors.

i understood the article and implemented the same in my project but really didn't get what i am missing.

The below is the output said in the article and what i am expecting is:

{
   "apierror":{
      "status":"BAD_REQUEST",
      "timestamp":"10-07-2019 12:53:24",
      "message":"Validation error",
      "subErrors":[
         {
            "object":"person",
            "field":"id",
            "rejectedValue":null,
            "message":"ID cannot be null"
         },
         {
            "object":"person",
            "field":"name",
            "rejectedValue":null,
            "message":"name cannot be null"
         }
      ]
   }
}

but below is what i am getting. i don't see the subErrors part at all.

{"message":"Validation Error","debugMessage":null,"detail":null,"httpStatus":"BAD_REQUEST","timestamp":"2019-07-10T17:08:00.52"}

Any help is appreciated.

Hello Saravana, Any errors? Also, share the suspected code instead of the whole project — Romil Patel
– Romil Patel, Commented Jul 10, 2019 at 12:29
can you please share on which controller endpoint you are making request — Romil Patel
– Romil Patel, Commented Jul 10, 2019 at 12:35
I am doing in the PersonController. Because of @Valid even before my return it is getting validated in my RestCustomExceptionHandler but the returned response doesn't have the subErrors part. Can you take a look at my code from github — Saravana Kumar M
– Saravana Kumar M, Commented Jul 10, 2019 at 12:41

Emanuel Ramirez · Accepted Answer · 2019-07-10 13:28:01Z

2

You need to add getter and setters in APICustomError for properly serialize your object. Also you need public constructor and getter/setters for inner class APIValidationError. I suggest you use Lombok.

After that you will see the errors, something like this...

{
   "message": "Validation Error",
   "debugMessage": null,
   "subErrors": [
       {
           "object": "personDTO",
           "field": "id",
           "rejectedValue": null,
           "validationErrorMessage": "ID cannot be null."
       }
   ],
   "detail": null,
   "httpStatus": "BAD_REQUEST",
   "timestamp": "2019-07-10T10:25:44.1705441"
}

edited Jul 10, 2019 at 13:28

answered Jul 10, 2019 at 13:01

Emanuel Ramirez

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4 Comments

Saravana Kumar M Over a year ago

The response format is a lot cluttered. The code from this article toptal.com/java/spring-boot-rest-api-error-handling produces the below output which is what i am expecting. {"apierror":{"status":"BAD_REQUEST","timestamp":"10-07-2019 06:41:32","message":"Validation error","subErrors":[{"object":"bird","field":"mass","rejectedValue":1.0E7,"message":"must be less than or equal to 104000"}]}}

Emanuel Ramirez Over a year ago

I missed that you were using an inner class in APICustomError, previous response was not you error handler. Now it is.

Saravana Kumar M Over a year ago

Great! After adding getters and setters. it is working as expected. Thanks a lot. Just a small question? Is this approach, a better of handling validations?

Emanuel Ramirez Over a year ago

As far as i know this is a good approach for proper error handling. In this cas you only use it for formatting, but it is a very common practice. Regards.

deHaar · Accepted Answer · 2019-07-11 07:47:21Z

0

Try this one In your controller advice

protected ResponseEntity<Object> handleMethodArgumentNotValid(
                MethodArgumentNotValidException ex,
                HttpHeaders headers, 
                HttpStatus status, WebRequest request) {
    Response response = new Response();
    List<FieldError> errors = ex.getBindingResult().getFieldErrors();
    List<SubError> errors = new ArrayList<>();

    for (FieldError e : errors) {
        SubError error = new SubError():
        error.setMessage(String.format(MESSAGE_FORMAT, egetCOde));
        errors.add(error);
    }
    response.setSubError(errors);
    return new ResponseEntity(response, HttpStatus.BAD_REQUEST);
}

edited Jul 11, 2019 at 7:47

deHaar

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answered Jul 11, 2019 at 7:44

Rajan Khurana

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