在ObjectStateManager中找不到具有与提供对象的键匹配的键的对象 [英] An object with a key that matches the key of the supplied object could not be found in the ObjectStateManager

问题描述

我想从 FormView 中更新 ObjectDataSource 的记录，并且失去了解决此错误的一天。

I want to update record from FormView with ObjectDataSource and lose my day to solve this error.

具有与提供对象的键匹配的键的对象可以在ObjectStateManager中找到
。验证提供的对象的
的键值是否与必须应用
更改的对象的键值相匹配。

An object with a key that matches the key of the supplied object could not be found in the ObjectStateManager. Verify that the key values of the supplied object match the key values of the object to which changes must be applied.

我的代码在

private static Entities1 _db = null;

public static Entities1 CreateDataContext()
{
    if (_db == null)
    {
        _db = new Entities1(System.Configuration.ConfigurationManager.ConnectionStrings["Entities1"].ConnectionString);
        _db.games.MergeOption = MergeOption.NoTracking;
        _db.my_aspnet_users.MergeOption = MergeOption.NoTracking;
        _db.platforms.MergeOption = MergeOption.NoTracking;
    }
    return _db;
}

public void Update(game item)
{
    Entities1 DB = CreateDataContext();
    item.modified = DateTime.Now;
    var obj = (from u in DB.games
               where u.idgames == item.idgames
               select u).First();
    DB.games.ApplyCurrentValues(item);//Error Here
    DB.SaveChanges();         
}

推荐答案

在您的方法中：

In your method:

public void Update(game item)
{
    Entities1 DB = CreateDataContext();
    item.modified = DateTime.Now;
    var obj = (from u in DB.games
               where u.idgames == item.idgames
               select u).First();
    DB.games.ApplyCurrentValues(item);//Error Here
    DB.SaveChanges();         
}

项目不是附加，所以它不能更新。这几乎是错误信息告诉你的。

item is not attached so it can't be updated. That's pretty much what the error message is telling you, too.

看起来你想使用 obj 从您的上下文检索。然后将 obj 的值设置为项目中的值，然后使用 obj 进行更新。

It looks like you'd want to use obj which is retrieved from your context. Then set the values of obj to those in item, and use obj to make the updates.

编辑样本 ...

如果您只想设置修改的日期和时间，您可以执行此操作：

If you just want to set the modified date and time you'd do this:

public void Update(game item) {
    Entities1 DB = CreateDataContext();

    var obj = (from u in DB.games
               where u.idgames == item.idgames
               select u).SingleOrDefault();
    if (obj == null) {
      // handle the case where obj isn't found
      // probably by throwing an exception
    }

    obj.modified = DateTime.Now;
    DB.games.ApplyCurrentValues(obj);
    DB.SaveChanges(); 
}

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