支持动态更新管理员密码和下载次数逻辑完善，优化相关错误处理和配置更新流程

internal/service/batch_service.go

@@ -85,8 +85,18 @@ func (s *BatchService) DeleteBatch(ctx context.Context, batchID string) error {
 }
 
 func (s *BatchService) IncrementDownloadCount(batchID string) error {
-	return s.db.Model(&model.FileBatch{}).Where("id = ?", batchID).
-		UpdateColumn("download_count", gorm.Expr("download_count + ?", 1)).Error
+	if batchID == "" {
+		return errors.New("batch id is empty")
+	}
+	result := s.db.Model(&model.FileBatch{}).Where("id = ?", batchID).
+		UpdateColumn("download_count", gorm.Expr("download_count + ?", 1))
+	if result.Error != nil {
+		return result.Error
+	}
+	if result.RowsAffected == 0 {
+		return errors.New("batch not found or already deleted")
+	}
+	return nil
 }
 
 func (s *BatchService) GeneratePickupCode(length int) (string, error) {