The instance of entity type 'xxx' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked.
具体详细错误信息:The instance of entity type 'xxx' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached. Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging' to see the conflicting key values.
代码片段:
foreach (var item in list) { var func = this.GetCodeCheckFunction(item); var gauge = UnitWork.FindSingle(func); if (gauge == null) { //新增 UnitWork.Add(item); } else { //修改 gauge.GaugeType = item.GaugeType; gauge.ModifiedBy = _auth.GetCurrentUser().User.Id; gauge.ModifiedTime = DateTime.Now; UnitWork.Update(gauge); } UnitWork.Save(); }
介绍下业务场景:导入时excel中存在重复数据。更新数据用的UnitWork。
上面的报错信息很明显了,它告诉我们一条数据已经被trace了,不能重复trace,只要我们把这条被trace的数据取消就行了。
下面是修改后的代码:
foreach (var item in list) { var func = this.GetCodeCheckFunction(item); var gauge = _dbContext.MesInfoGauges.FirstOrDefault(func); if (gauge == null) { //新增 _dbContext.MesInfoGauges.Add(item); _dbContext.SaveChanges(); _dbContext.Entry(item).State = EntityState.Detached; } else { //修改 gauge.GaugeType = item.GaugeType; gauge.ModifiedBy = user.Id; gauge.ModifiedTime = DateTime.Now; _dbContext.MesInfoGauges.Update(gauge); _dbContext.SaveChanges(); _dbContext.Entry(gauge).State = EntityState.Detached; } }
保存后,修改当前数据的Entry状态为Detached。