什么也部分的.WithRequired在EF流利的API玩？ [英] What part does the .WithRequired play in an EF Fluent API?

问题描述

如果我有以下对象：

public class Application 
{
    public int ApplicationId { get; set; }
    public string Name { get; set; }
    public virtual ICollection<TestAccount> TestAccounts { get; set; }
}

public class TestAccount
{
    public int TestAccountId { get; set; }
    public int ApplicationId { get; set; }
    public string Name { get; set; }
    public virtual Application Application { get; set; }
}

EF映射是这样的：

EF Mapping looks like this:

modelBuilder.Entity<Application>()
    .HasMany(a => a.TestAccounts)
    .WithRequired(t => t.Application)
    .WillCascadeOnDelete(false);

这两者之间的关系是，我可以申请零或多个TestAccounts。

The relationship between these two is that I can have applications with zero or many TestAccounts.

我想说明两个表之间的FK关系。有人可以解释什么是.WithRequired一样。我不明白为什么这是必要的。

I am trying to describe a fk relationship between the two tables. Can someone explain what the ".WithRequired" does. I don't understand why this is needed.

推荐答案

这意味着，每个 TestAccount 实体必须有一个应用程序实体想一个办法把它是这样的：

It means that each TestAccount entity MUST have an Application entity associated with it.I suppose one way to put it is like this:

如果你的数据库，你有一个外键到另一个表和外键不为空，然后使用 WithRequired ，否则，如果它可以为NULL，然后用 WithOptional

If in your DB, you have a foreign key to another table and that foreign key is NOT NULL, then use WithRequired, else if it can be NULL, then use WithOptional

下面是一些文档值得看的：

Here is some documentation worth looking at:

<一个href="http://msdn.microsoft.com/en-us/data/jj591620.aspx">http://msdn.microsoft.com/en-us/data/jj591620.aspx

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