EF代码优先：一对一的单向关系 [英] EF Code First: One-to-One One-way Relationship

问题描述

我通常具有以下结构：

MyClass
public virtual ICollection<Version> Versions { get; set; }
public virtual Version CurrentVersion { get; set; }

也就是说，有一个东西列表，有些类都指向该列表，并且该列表中的一个特定项目-许多版本的当前版本，事件列表中的下一个即将发生的事件，等等。

That is, there is a list of stuff, and some class both points to that list, and one specific item in that list - either the current version of many versions, the next upcoming event in a list of events, etc.

在我的模式中，我想要最后是一个从Version指向MyClass的外键-可以正常工作。但是然后我想要一个外键，从MyClass指向代表CurrentVersion属性的Version，而没有外键指向后方-我不希望多余的存储空间或麻烦告诉Version的MyClass是CurrentVersion的版本（如果有）。换句话说，我希望第二种关系是从MyClass到Version的单向关系，即使它是一对一的。

In my schema what I'd like to end up with is a Foreign Key pointing from Version to MyClass - that much works out properly. But then I'd like a Foreign Key pointing from MyClass to Version representing the CurrentVersion property, with no Foreign Key pointing back - I don't want the extra storage or bother of telling a Version what MyClass it's the CurrentVersion for, if any. Put another way, I'd like this second relationship to be one-way from MyClass to Version, even though it's one-to-one.

EF Code First提供的功能相反，我是第一个属性上的正常一对多，从版本到MyClass的FK，但是第二个属性上是完整的一对一关系，而FK指向两个方向-因此，版本以MyClass_Id和MyClass_Id1结尾。

What EF Code First gives me instead is the normal one-to-many on the first property, with the FK from Version to MyClass, but then a full one-to-one relationship on the second property with an FK pointing in both directions - so the underlying schema for Version ends up with MyClass_Id and MyClass_Id1.

因此，有没有办法在不借助Fluent API的情况下在EF Code First中获得单向关系？看起来好像是System.ComponentModel.DataAnnotations.Schema.InverseProperty，但它似乎没有提供说不生成一个的方法。

So, is there a way to get a one-way relationship in EF Code First without resorting to the Fluent API? It looked like maybe System.ComponentModel.DataAnnotations.Schema.InverseProperty had a shot at it, but it didn't seem to offer a way to say "Don't generate one."

推荐答案

关键是在指向该属性的属性上指定InverseProperty，以便EF意识到这是多对多的，而不是一对多的。

The key is to specify the InverseProperty on the property that points back, so that EF realizes it's to the Many-to-Many, not to the One-to-One.

public class MyClass
{
    public int Id { get; set; }

    public Version CurrentVersion { get; set; }

    public ICollection<Version> Versions { get; set; }
}

public class Version
{
    public int Id { get; set; }

    [InverseProperty("Versions")]
    public Versioned Versioned { get; set; }
}

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