[转] EF cannot be tracked because another instance of this type with the same key is already being tracked
cannot be tracked because another instance of this type with the same key is already being tracked
If you load the entity from the context you cannot attach an entity with the same key again.
The first entity is still kept in internal context cache and context can hold only one instance with given key value per type (it is called identity map and I described it here in other situation).
You can solve it by detaching former instance but you don't have to. If you only need to save new values you can use this:
- ObjectContext API:
context.YourEntitySet.ApplyCurrentValues(newEntity); - DbContext API:
context.Entry(oldEntity).CurrentValues.SetValues(newEntity);
[转] EF cannot be tracked because another instance of this type with the same key is already being tracked的更多相关文章
- The instance of entity type 'Menu' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked.
这里记录一个在使用.net core中ef core执行数据库操作时遇到的问题: 我在代码中使用DbContext下的Update方法准备将更改后的数据像这样步到数据库: _context.Menus ...
- The instance of entity type 'xxxx' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked.
一.问题描述 问题:The instance of entity type 'xxxx' cannot be tracked because another instance with the sam ...
- type parameters of <T>T cannot be determined; no unique maximal instance exists for type variable T with upper bounds int,java.lang.Object
今天在进行代码检查的时候出现下面的异常: type parameters of <T>T cannot be determined; no unique maximal instance ...
- EF 更新实体 The instance of entity type 'BabyEvent' cannot be tracked because another instance
加上AsNoTracking. 人不能两次踏入同一条河. 我 就踏入了.o(╥﹏╥)o
- The instance of entity type 'manager' 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 ent
最近在用ASP.NET CORE时遇到一些问题,现记录下: 出现上述错误,即在更新实体数据时出现的错误 services.AddDbContext<StoreContext>(c => ...
- EF关于报错Self referencing loop detected with type的原因以及解决办法
1)具体报错 { "Message": "出现错误.", "ExceptionMessage": "“ObjectContent` ...
- EF 6.0 The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value. c#中的时间
在SQL server 中,有两种日期时间类型: 1.DateTime 它的范围是 1753-1-1 至 9999-12-31 2.DateTime2 它的满园是 0001-01-01 至 9999- ...
- 使用Ef查询出现的问题The cast to value type 'System.Boolean' failed because the materialized value is null.的解决方法
把值类型的系统.布尔的失败是因为物化值是null.结果类型的泛型参数或查询必须使用可空类型. 解决方法: 请确保你查询中的字段值不为空或者做为空判断
- EF 5 最佳实践白皮书
Performance Considerations for Entity Framework 5 By David Obando, Eric Dettinger and others Publish ...
随机推荐
- ubuntu没有权限（不能）创建文件夹（目录）
可以在终端直接运行 sudo nautilus,弹出来的nautilus可以直接GUI操作,中途别关终端.如果遇到需要输入root密码,则输入root密码就可以启动这个图形界面了.
- 钩子(hook)编程
一.钩子介绍 1.1钩子的实现机制 钩子英文名叫Hook,是一种截获windows系统中某应用程序或者所有进程的消息的一种技术.下图是windows应用程序传递消息的过程: 如在键盘中按下一键,操作系 ...
- Effective Java笔记
chapter 1 java支持四种类型:interface,class,array,primitive(基本类型) chapter 2 创建对象方式: ①构造器 ②静态工厂方法代替构造器:名称可以按 ...
- day08.2-ssh远程连接服务
在Linux环境中,部署一个服务的一般步骤: a). 准备环境,包括 关闭防火墙:service iptables stop(或chkconfig iptables off) 关闭se ...
- 20165219 2017-2018-2 《Java程序设计》第9周学习总结
20165219 2017-2018-2 <Java程序设计>第9周学习总结 课本知识总结 URL类 URL类是java.net包中的一个重要的类,使用URL创建对象的应用程序称为客户端程 ...
- oracle查询分区表中的数据
select * from TABLE_NAME partition(分区名) T WHERE T.COL_NAME= 'XX';
- 【转】asp.net中设置弹出谈话框的几种方式详解
源地址:https://blog.csdn.net/zou15093087438/article/details/79637114 注:可用winform的MessageBox的方法,只需引用Syst ...
- MySQL 学习笔记（三）：完整性和触发器设计
(一)完整性设计 方法一.在设计表时定义约束 删除数据库school,建立新数据库school1 drop database school; create database school; use s ...
- zabbix 3.0 快速安装文档
下载地址:http://www.zabbix.com/download.php 官方文档:https://www.zabbix.com/documentation/3.0/manual/install ...
- php文件下载方法收藏（附js下载技巧）
function down($url){ header('Content-Description: File Transfer'); header('Content-Type: application ...