是什么dbcontext.Add和dbcontext.AddObject之间的区别 [英] What is difference between dbcontext.Add and dbcontext.AddObject

问题描述

我是初学者在WPF。我想知道，是什么 dbcontext.Add 和 dbcontext.AddObject 之间的区别。

I am beginner at WPF. I want to know that what is difference between dbcontext.Add and dbcontext.AddObject.

private void AddButton_Click(object sender, RoutedEventArgs e)
{
        Name employee = new Name();
        employee.Name1 = "Test";
        dataContext.Names.AddObject(employee);
}

我想实现这个 dbcontext.AddObject（）。但我得到一个错误：

I want to achieve this dbcontext.AddObject(). But I get an error:

System.Data.Entity.DbSet不包含ADDOBJECT'，没有扩展方法'ADDOBJECT接受第一种类型System.Data.Entity.DbSet'的参数的定义可以找到（是否缺少？using指令或程序集引用）C：\文档\的Visual Studio 2012 \项目\ WpfApplication9 \ WpfApplication9 \ MainWindow.xaml.cs 49 31 WpfApplication9`

'System.Data.Entity.DbSet' does not contain a definition for 'AddObject' and no extension method 'AddObject' accepting a first argument of type 'System.Data.Entity.DbSet' could be found (are you missing a using directive or an assembly reference?) C:\Documents\Visual Studio 2012\Projects\WpfApplication9\WpfApplication9\MainWindow.xaml.cs 49 31 WpfApplication9`

同时建议哪一个更好。谢谢你。

Also suggest which one is better. Thank you.

推荐答案

其实你是在谈论 ADDOBJECT 对象集和其中的方法; TEntity＆GT; 类，它是用旧的ObjectContext 。但由于实体框架4，我们有的DbContext 类（这是一个包装过的老的ObjectContext ）。这个新的类使用 DbSet＆LT; TEntity＆GT; 代替旧对象集＆LT; TEntity＆GT; 。新的组类有方法添加。

Actually you are talking about AddObject method of ObjectSet<TEntity> class which was used by old ObjectContext. But since Entity Framework 4 we have DbContext class (which is a wrapper over old ObjectContext). This new class uses DbSet<TEntity> instead of old ObjectSet<TEntity>. New set class has method Add.

所以，回到差异。旧的实现调用 ADDOBJECT 的方法的ObjectContext ：

So, back to differences. Old implementation invoked AddObject method of ObjectContext:

public void AddObject(TEntity entity)
{
    Context.AddObject(FullyQualifiedEntitySetName, entity);
}

新的实现做同样的事（见行动参数）：

New implementation does same thing (see action parameter):

public virtual void Add(object entity)
{
    ActOnSet(() => ((InternalSet<TEntity>) this).InternalContext.ObjectContext.AddObject(((InternalSet<TEntity>) this).EntitySetName, entity),  
              EntityState.Added, entity, "Add");
}

正如你可以看到同样的 ObjectContext.AddObject 方法在内部调用。是什么改变了 - pviously我们刚才添加$ P $实体背景，但现在如果有表项存在于ObjectStateManager，那么我们就改变进入状态，以添加：

As you can see same ObjectContext.AddObject method is called internally. What was changed - previously we just added entity to context, but now if there is state entry exists in ObjectStateManager, then we just changing state of entry to Added:

if (InternalContext.ObjectContext.ObjectStateManager.TryGetObjectStateEntry(entity, out entry))
{
    entry.ChangeState(newState); // just change state
}
else
{
    action(); // invoke ObjectContext.AddObject
}

新的API主要目标是使的DbContext 更容易使用。

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