argos/dmp-backend/web/src/main/java/eu/eudat/controllers/controllerhandler/ControllerValidatorErrorHandler.java

package eu.eudat.controllers.controllerhandler;

import eu.eudat.models.data.errormodels.ValidationErrorContext;
import eu.eudat.models.data.helpers.responses.ResponseItem;
import eu.eudat.types.ApiMessageCode;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.context.i18n.LocaleContextHolder;
import org.springframework.http.HttpStatus;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.ResponseStatus;

import java.util.List;
import java.util.Locale;


@ControllerAdvice
public class ControllerValidatorErrorHandler {

    private MessageSource messageSource;

    @Autowired
    public ControllerValidatorErrorHandler(MessageSource messageSource) {
        this.messageSource = messageSource;
    }

    @ExceptionHandler(MethodArgumentNotValidException.class)
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ResponseBody
    public ResponseItem<ValidationErrorContext> processValidationError(MethodArgumentNotValidException ex) {
        BindingResult result = ex.getBindingResult();
        List<FieldError> fieldErrors = result.getFieldErrors();

        return processFieldErrors(fieldErrors);
    }

    private ResponseItem<ValidationErrorContext> processFieldErrors(List<FieldError> fieldErrors) {
        ValidationErrorContext dto = new ValidationErrorContext();

        for (FieldError fieldError : fieldErrors) {
            String localizedErrorMessage = resolveLocalizedErrorMessage(fieldError);
            dto.addFieldError(fieldError.getField(), localizedErrorMessage);
        }

        return new ResponseItem<ValidationErrorContext>().status(ApiMessageCode.VALIDATION_MESSAGE).payload(dto);
    }

    private String resolveLocalizedErrorMessage(FieldError fieldError) {
        Locale currentLocale = LocaleContextHolder.getLocale();
        String localizedErrorMessage = messageSource.getMessage(fieldError, currentLocale);

        if (localizedErrorMessage.equals(fieldError.getDefaultMessage())) {
            String[] fieldErrorCodes = fieldError.getCodes();
            localizedErrorMessage = fieldErrorCodes[0];
        }

        return localizedErrorMessage;
    }
}