change error handling

model/errors.go

@@ -29,4 +29,6 @@ var (
 	ErrInvalidTx = errors.New("invalid tx")
 	// ErrDeadlineExceeded deadline exceeded
 	ErrDeadlineExceeded = errors.New("deadline exceeded")
+	// ErrDuplicatedAnswered
+	ErrDuplicatedAnswered = errors.New("duplicated answered is not allowed")
 )

model/respondents_impl.go

@@ -98,17 +98,15 @@ func (*Respondent) InsertRespondent(ctx context.Context, userID string, question
 		}
 	}
 
-	if !questionnaire.IsDuplicateAnswerAllowed && submittedAt.Valid {
-		// delete old answers
+	if !questionnaire.IsDuplicateAnswerAllowed {
 		err = db.
 			Where("questionnaire_id = ? AND user_traqid = ?", questionnaireID, userID).
-			Delete(&Respondents{}).Error
-		// 既存の回答がなかった場合はそのまま進む
-		if errors.Is(err, ErrNoRecordDeleted) {
-			err = nil
+			First(&Respondents{}).Error
+		if err == nil {
+			return 0, ErrDuplicatedAnswered
 		}
-		if err != nil {
-			return 0, fmt.Errorf("failed to delete old answers: %w", err)
+		if !errors.Is(err, gorm.ErrRecordNotFound) {
+			return 0, fmt.Errorf("failed to check duplicate answer: %w", err)
 		}
 
 	}

router/responses.go

@@ -166,6 +166,9 @@ func (r *Response) PostResponse(c echo.Context) error {
 	}
 
 	responseID, err := r.InsertRespondent(c.Request().Context(), userID, req.ID, null.NewTime(submittedAt, !req.Temporarily))
+	if errors.Is(err, model.ErrDuplicatedAnswered) {
+		return echo.NewHTTPError(http.StatusConflict, err)
+	}
 	if err != nil {
 		c.Logger().Errorf("failed to insert respondent: %+v", err)
 		return echo.NewHTTPError(http.StatusInternalServerError, err)