Response error format with manual validation in Spring Data Rest - spring

Question

When using Spring Data REST and JSR 303 Bean Validation I get a response like the following when there's a constraint violation:
{
"errors": [
{
"entity": "Empresa",
"property": "observacao",
"invalidValue": "",
"message": "O tamanho do campo deve ser entre 1 e 255"
}
]
}
But I'm trying to validate an object manually, and I would like to return the validation errors in the same format used by Spring Data Rest.
#DeleteMapping("/departamento/{id}")
public #ResponseBody
ResponseEntity<?> filtro(#PathVariable Long id){
Optional<Departamento> departamentoOpt = this.departamentoRepository.findById(id);
if (!departamentoOpt.isPresent()) {
return ResponseEntity.notFound().build();
}
Departamento departamento = departamentoOpt.get();
BindingResult errors = new BeanPropertyBindingResult(
departamento, "departamento");
this.validator.validate(departamento, errors, PreDeleteValidation.class);
if (errors.hasErrors()) {
// How to return a response in the same format used by SDR here?
}
return ResponseEntity.ok().build();
}
How can this be accomplished?

Answer 1

You can throw and Exception on validation failure and register a Spring MVC Controller Advice to catch this and transform it to something that meets your needs.
if (errors.hasErrors()) {
throw new org.springframework.web.bind.MethodArgumentNotValidException(
departamento, bindingResult)
}
The advice could look something like the below:
#ControllerAdvice
public class ErrorHandlingAdvice
{
#ExceptionHandler(MethodArgumentNotValidException.class)
#ResponseStatus(HttpStatus.BAD_REQUEST)
#ResponseBody
public ValidationError processValidationError(MethodArgumentNotValidException ex)
{
ValidationError error = new ValidationError();
BindingResult result = ex.getBindingResult();
List<FieldError> fieldErrors = result.getFieldErrors();
for (FieldError fieldError : fieldErrors)
{
error.addError(fieldError.getField(), fieldError.getDefaultMessage());
}
return error;
}
}
ValidationError is just a simple bean:
public class ValidationError
{
private final Map<String, List<String>> errors;
public ValidationError()
{
errors = new TreeMap<>();
}
public void addError(String field, String error)
{
if (!errors.containsKey(field))
{
errors.put(field, new ArrayList<String>());
}
errors.get(field).add(error);
}
public Map<String, List<String>> getErrors()
{
return errors;
}
}