如何在不访问对象上下文的情况下删除Entity Framework中的关联对象 [英] How to delete an associated object in Entity Framework without having access to the object context

问题描述

具有两个模型，即站点和链接，其中一个站点具有许多链接，如何从不能访问对象上下文的Site方法中删除一个链接？

Having two models, Site and Link, where a site has many links, how do I delete a link from inside a method of Site, which doesn't have access to the object context?

我尝试过类似的操作：

public void DeleteFirstLink() {
    var link = LinkSet.First();
    LinkSet.Remove(link);
}

似乎并不是真正删除链接，而是破坏了关联。由于存在数据库约束，因此会引发此错误：

but it seems that is not really deleting the link, but breaking the association. Since there's a database constraints it throws this error:

正在从AssociationSet'Sites_have_Links'中添加或删除关系。受基数约束，还必须添加或删除相应的链接。

A relationship is being added or deleted from an AssociationSet 'Sites_have_Links'. With cardinality constraints, a corresponding 'Links' must also be added or deleted.

实际上如何从数据库中删除链接？

How do I actually delete the link from the database?

推荐答案

假定在调用DeleteFirstLink（）方法时ObjectContext不活跃，则可以通过旋转一个方法中的上下文，附加Site实体，然后删除链接：

Assuming that your ObjectContext is not alive when you call the DeleteFirstLink() method, you can make it work by spinning up a context inside the method, attaching the Site entity, and then deleting the link:

public void DeleteFirstLink()
{
  using (ProjectEntities db = new ProjectEntities())
  {
    db.AttachTo("[your site EntitySet name - SiteSet?]", this);
    var link = LinkSet.First();
    db.DeleteObject(link);
    LinkSet.Remove(link);
    db.SaveChanges();
  }
}

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