调用的EntityFramework的SaveChanges时重复进行 [英] Entityframework duplicating when calling savechanges

问题描述

我使用的EntityFramework 5代码首先，我有一个这样的模式。

I am using entityframework 5 code first, I have a model like this.

class Product {
    public Product() {
        Fabrics = new BindingList<FabricLineItem>();
    }
    ...
    public virtual ICollection<FabricLineItem> Fabrics { get;set; }
}

class FabricLineItem {
    [ForeignKey("Fabric")]
    public int FabricId { get; set; }  
    public virtual Product Product { get;set; }
    public virtual Fabric Fabric { get;set; }  
}

class Fabric {
    ...
}

我已经在我的数据库面料。我创建了一个新的产品对象和一些fabriclineitems添加到集合。当我尝试保存产品发生的事情是它复制了织物在数据库中并调用后

I already have fabrics in my database. I create a new product object and add some fabriclineitems to the collection. When I try to save product what happens is it duplicates the fabric in the database and reference it to the new one after calling

 DataContext.SaveChanges(); 

调用的SaveChanges在调试器的值是否正确调用在更改以后过吗？任何想法，为什么我收到这种奇怪的行为？

Before the call to savechanges the values in the debugger are correct by after calling they are changed ? Any idea why I am getting this strange behavior ?

推荐答案

我怀疑是上下文不知道该面料是不是新项目 - 所以它增加了/将它们插入

I suspect that the context does not know that the Fabrics are not new items - so it adds/inserts them.

如果您将面料到DataContext（以不变/ NotModified） - 或从数据库中选择它们，然后当调用SaveChanges（）被称为上下文知道现有架构对象，然后可以只为新FabricLineItem导航关系，而无需创建一个新的Fabric

If you attach the fabrics to the DataContext (as Unchanged/NotModified) - or select them from the database, then when SaveChanges() is called the context knows about existing Fabric objects and can then just create a navigation relationship for the new FabricLineItem without creating a new Fabric

EF是很多笨比看起来 - 你真的需要告诉它几乎一切

EF is a lot 'dumber' than it looks - you really need to tell it almost everything.

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