MapKey vs HasForeignKey差异 - 流利的Api [英] MapKey vs HasForeignKey Difference - Fluent Api

问题描述

实际上有什么区别：

this.HasRequired(a => a.Something)
    .WithMany()
    .Map(a => a.MapKey("SomethingId"));

和

this.HasRequired(a => a.Something)
    .WithMany()
    .HasForeignKey(a => a.SomethingId);

推荐答案

两个映射都将创建完全相同的数据库模式，不可空的外键 SomethingId 和两个相关表之间的参照约束。

Both mappings will create exactly the same database schema with a non-nullable foreign key SomethingId and a referential constraint between the two related tables.

第一个映射为 MapKey 当您不想将外键作为模型类中的属性时使用。在这种情况下，关联的类型称为独立关联 。当外键是模型中的属性时，您将应用第二个映射 HasForeignKey 。这种类型称为外键协会。

The first mapping with MapKey is used when you don't want to have the foreign key as a property in your model class. The type of association in this case is called Independent Association. You would apply the second mapping with HasForeignKey when the foreign key is a property in the model. This type is called Foreign Key Association.

在许多情况下，使用外键协会更容易，但是很多人认为它较少清洁在对象世界中有一个关系人工制品（外键），并且喜欢独立协会。

In many scenarios it is easier to work with Foreign Key Associations, but many people consider it as less clean to have a relational artifact (a foreign key) in the object world and prefer Independent Associations therefore.

这里有一些关于两种类型的关联的参考，缺点：

Here are some references about the two types of associations and their Pros and Cons:

• http://www.ladislavmrnka.com/2011/05/foreign-key-vs-independent-associations-in-ef-4/


• 什么是独立协会和外国关键协会？


• 代码第一：独立为社会与外国关键协会？

• http://www.ladislavmrnka.com/2011/05/foreign-key-vs-independent-associations-in-ef-4/
• What are Independent Associations and Foreign Key Associations?
• Code First: Independent associations vs. Foreign key associations?

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