如何获得实体框架初始化集合在我的新创建的实体？ [英] How do I get the Entity Framework to initialise collections on my newly-created entities?

问题描述

我试图用带有一些测试数据 IDatabaseIntialiser 这样的种子我的数据库：

I'm trying to seed my database with some test data with an IDatabaseIntialiser like this:

protected override void Seed(BlogDataContext context)
{
    // <snip>
    var post = context.Posts.Create();
    post.Title = "My Life On Twitter";
    // <snip properties>

    // Set tags
    post.Tags.Add(aspnetTag); // NullRefException
    post.Tags.Add(razorTag);

邮政实体看起来是这样的：

Post entity looks like this:

public class Post
{
    // ...
    public virtual ICollection<Tag> Tags { get; set; }

完全在实体到位桶：<一href="https://bitbucket.org/DanTup/dantup-blog/src/03cfceba726b/DanTup%20Blog/Models/Post.cs">Post和<一href="https://bitbucket.org/DanTup/dantup-blog/src/03cfceba726b/DanTup%20Blog/Models/Tag.cs">Tag.所有code是在 HTTP：//$c$c.dantup.com/blog

Full entities at Bitbucket: Post and Tag. All code is at http://code.dantup.com/blog

不过， post.Tags 为空，所以这是行不通的。本来我是创造岗位作为新邮（），但是因为我打电话的EF提供的创建方法为什么是集不会被初始化？

However, post.Tags is null, so this doesn't work. Originally I was creating post as new Post(), however since I'm calling the Create method provided by the EF, why is the collection not initialised?

感觉笨拙在此实例我自己的收藏，如果我这样做，在构造函数中，presumably每次我打开从EF的实体，它会在构造函数中创建的集合，然后有一个覆盖它从数据库中包含实际数据？

It feels clumsy to instantiate my own collection here, and if I do it in the constructor, presumably every time I load an entity from EF, it'll create the collection in the constructor and then overwrite it with one containing the actual data from the DB?

是否有某种方式来告诉EF创建我的实体，包括集合/代理我的 ICollections （假设的ICollection 是正确的选择）？

Is there some way to tell EF to create me an entity, including collections/proxies for my ICollections (assuming ICollection is the right choice)?

修改： context.Configuration.ProxyCreationEnabled 设置为true（默认），<一个href="http://msdn.microsoft.com/en-us/library/system.data.entity.infrastructure.dbcontextconfiguration.proxycreationenabled%28v=vs.103%29.aspx">which似乎存在这个原因？

Edit: context.Configuration.ProxyCreationEnabled is set to true (by default), which seems to exist for this reason?

推荐答案

使用POCO实体和EF，我一般初始化集合中的构造。而且，我preFER的ISet过的ICollection; - ）

With POCO entities and EF, I generally initialize collection in the constructor. And, I prefer ISet over ICollection ;-)

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