EF4.1代码优先：如何禁用在依赖实体中没有导航属性的关系的删除级联 [英] EF4.1 Code First : How to disable delete cascade for a relationship without navigation property in dependent entity

问题描述

  public class ParentEntity 
 {
 public int Id; 
公共虚拟ICollection< ChildEntity>儿童; 
} 
 
 public class ChildEntity 
 {
 public int Id; 
 public int ParentEntityId; //外键
 public virtual ParentEntity parent; // [NOTWANTED] 
} 
  

由于某些原因，我不希望ChildEntity把参考资料留给他的父母。我只是希望它保持ParentEntity ID，但没有更多。
到目前为止，没有问题，我只是删除[NOTWANTED]行，一切正常。

这里的问题是：如何禁用在这种情况下级联删除？

如果我仍然有父导航属性，它会很容易：

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

但是，如果没有导航属性，我不知道如何实现在关闭的时候禁用级联（当然，不是每个表都禁用它，而只是关系）。

我现在所做的是设置外键作为一个可为空的int，为了禁用级联删除，但这并不漂亮：

  public int？ ParentEntityId; //外键 - 可以为空可以删除级联删除
  

如何使用流利API？认为它应该是可能的。

解决方案

你必须从关联的另一端配置它：

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

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]
}

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.

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

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)

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).

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

How can I get it to work with fluent API? Think it should be possible.

解决方案

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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