The instance of entity type ‘xxx‘ cannot be tracked because another instance with the same key value
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2022-07-15 13:09:21
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asp.net core 3.1 环境:
场景: 一起执行几个方法体, 先在一个地方修改or添加一条记录;接着又在另个地方修改了该条记录,就会报如下错误:
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(entity: gauge).State = EntityState.Detached;
}
}
保存后,修改当前数据的Entry状态为Detached。
若为.netcore 2.2,则写法为:
_dbContext.Entry(gauge).State = EntityState.Detached;