package cn.home1.oss.lib.errorhandle.internal.resolver;
   
   import static com.google.common.collect.Lists.newLinkedList;
   
   import cn.home1.oss.lib.errorhandle.api.AbstractConcreteExceptionResolver;
   import cn.home1.oss.lib.errorhandle.api.ValidationError;
   
   import org.springframework.validation.BindingResult;
   import org.springframework.validation.FieldError;
  import org.springframework.validation.ObjectError;
  import org.springframework.web.bind.MethodArgumentNotValidException;
  
  import java.util.List;
  import java.util.Optional;
  
  public class MethodArgumentNotValidExceptionResolver //
    extends AbstractConcreteExceptionResolver<MethodArgumentNotValidException> {
  
    @Override
    public Optional<List<ValidationError>> validationErrors(final MethodArgumentNotValidException exception) {
      final List<ValidationError> validationErrors = newLinkedList();
  
      final BindingResult bindingResult = exception.getBindingResult();
      for (final ObjectError err : bindingResult.getGlobalErrors()) {
        validationErrors.add(ValidationError.validationErrorBuilder() //
          .message(err.getDefaultMessage()) //
          .build() //
        );
      }
      for (final FieldError err : bindingResult.getFieldErrors()) {
        final Object rejectedValue = err.getRejectedValue();
        final String rejected = rejectedValue != null ? rejectedValue.toString() : null;
        validationErrors.add(ValidationError.validationErrorBuilder() //
          .field(err.getField()) //
          .rejected(rejected) //
          .message(err.getDefaultMessage()) //
          .build() //
        );
      }
  
      return Optional.of(validationErrors);
    }
  }