使用EF code第一种方式时MVC净级联删除 [英] MVC .Net Cascade Deleting when using EF Code First Approach

问题描述

我是pretty的新MVC和我遇到的麻烦与级联删除。对于我的模型我以下2类：

I'm pretty new to MVC and i'm having troubles with cascade deleting. For my model I the following 2 classes:

    public class Blog
    {
        [Key]
        public int Id { get; set; }
        [Required]
        public string Name { get; set; }
        [DisplayFormat()]
        public virtual ICollection<BlogEntry> BlogEntries { get; set; }
        public DateTime CreationDateTime { get; set; }
        public string UserName { get; set; }
    }

    public class BlogEntry
    {
        [Key]
        public int Id { get; set; }
        [Required]
        public string Title { get; set; }
        [Required]
        public string Summary { get; set; }
        [Required]
        public string Body { get; set; }
        public List<Comment> Comments { get; set; }
        public List<Tag> Tags { get; set; }
        public DateTime CreationDateTime { get; set; }
        public DateTime UpdateDateTime { get; set; }
        public virtual Blog ParentBlog { get; set; }

    }

和我的控制器我把他删除后的下背部：

And for my controller I set he following on delete post back:

[HttpPost, ActionName("Delete")]
public ActionResult DeleteConfirmed(int id)
{
    Blag blog = db.Blogs.Find(id);

    foreach (var blogentry in blog.BlogEntries)
    {
        //blogentry = db.BlogEntries.Find(id);
        db.BlogEntries.Remove(blogentry);
    }
    db.Blogs.Remove(blog);
    db.SaveChanges();
    return RedirectToAction("Index");
}

问题是，它不会工作，不管是什么; <一href="http://stackoverflow.com/questions/5825799/cascade-delete-rule-in-ef-4-1-$c$c-first-when-using-shared-primary-key-associati">I阅读这篇文章但我似乎只工作模式，其中的关系是一一对应的，所以我在这里失去了，我有搜索无处不在，找不到这个问题的解决方案，如果有的可以点什么我失踪那将是非常好的:)，在此先感谢，并再次，原谅我nooobness我刚开始起步，但要解决的一个大项目，以便能够学到很多东西。

Problem is it wont work no matter what; I read this post but i seem to only work for models where the relation is one to one, so i'm lost here, i have search everywhere, and can't find the solution for this problem, if some could point out what i'm missing it would be really nice :), thanks in advance, and again, pardon my nooobness i'm just getting started, but wanted to tackle a big project to be able to learn a lot.

推荐答案

这是因为EF在默认情况下不强制执行级联删除可选的关系。在模型中的关系推断为可选。

That is because EF by default does not enforce cascade deletes for optional relationships. The relationship in your model is inferred as optional.

您可以添加一个不为空的标量属性（BlogId <$ C C $>）的FK的

You can add a non nullable scalar property(BlogId) of the FK

public class BlogEntry
{
    [Key]
    public int Id { get; set; }
    [Required]
    public string Title { get; set; }
    [Required]
    public string Summary { get; set; }
    [Required]
    public string Body { get; set; }
    public List<Comment> Comments { get; set; }
    public List<Tag> Tags { get; set; }
    public DateTime CreationDateTime { get; set; }
    public DateTime UpdateDateTime { get; set; }

    public int ParentBlogId { get; set; }

    public virtual Blog ParentBlog { get; set; }
}

或配置此用流利的API

Or configure this using fluent API

   modelBuilder.Entity<BlogEntry>()
            .HasRequired(b => b.ParentBlog)
            .WithMany(b => b.BlogEntries)
            .WillCascadeOnDelete(true);

这篇关于使用EF code第一种方式时MVC净级联删除的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！