EF4.1代码首先：如何禁用级联删除在相关的实体没有导航财产有关系 [英] EF4.1 Code First : How to disable delete cascade for a relationship without navigation property in dependant entity

问题描述

下面是我的问题。
比方说，我有这两个非常基本的实体：

Here is my problem. Let's say I have these two very basic entities :

public class ParentEntity
{
   public int Id;
   public virtual ICollection<ChildEntity> Childrens;
}

public class ChildEntity
{
   public int Id;
   public int ParentEntityId; // Foreign Key
   public virtual ParentEntity parent; // [NOTWANTED]
}

对于一些原因，我不希望ChildEntity持有参考回到他的父母。我只是希望它保持ParentEntity ID，但仅此而已。
到现在为止，没有问题，我只是删除[NOTWANTED]行，一切都按预期工作。

For some reasons, I don't want the ChildEntity to hold a reference back to his parent. I just want it to keep the ParentEntity id but nothing more. Up until now, no problem, I just delete the [NOTWANTED] line, and everything works as expected.

在这里我的问题是：如何禁用？级联在特定的情况下删除

My problem here is : how to disable the cascade delete in that specific case ?

如果我仍然有父导航属性这将是一样容易：

If I still had the parent navigation property it would be as easy as :

modelBuilder.Entity<ChildEntity>()
    .HasRequired(c => c.parent)
    .WithMany(p => p.Childrens)
    .WillCascadeOndelete(false)

但没有导航属性我不知道我怎样才能实现要禁用删除级联（不包括全球禁用它，当然，也不是每个表中，但只是为关系）。

However without the navigation property I have no idea how I can achieve to disable the cascade on delete (without disabling it globally of course, nor per table, but just for the relation).

什么我现在做的是设置外键作为一个可空INT，以禁用删除级联，但是这并不漂亮：

What I have done right now is to set the foreign key as a nullable int, in order to disable the cascade on delete, but that's not pretty :

public int? ParentEntityId; // Foreign Key - nullable just to disable cascade on delete

任何想法我如何能得到它的工作用流利的API？认为应该是可能的...

Any idea how I can get it to work with fluent API ? Think it should be possible ...

谢谢！

推荐答案

你必须从联想的另一面配置：

You must configure it from the other side of the association:

modelBuilder.Entity<ParentEntity>()
    .HasMany(p => p.Children)
    .WithRequired()
    .HasForeignKey(c => c.ParentEntityId)
    .WillCascadeOnDelete(false);

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