定义两个外键在实体框架的主键 [英] Defining two foreign keys as primary key in Entity Framework

问题描述

在实体框架，我想用两个外键的另一个实体类型的主键。

In Entity Framework, I'd like to use two foreign keys as primary key of another entity type.

public class CustomerExtensionValue {

    // Values for extended attributes of a customer
    [Key]
    [Column(Order = 0)]
    public Customer Customer { get; set; }

    [Key]
    [Column(Order = 1)]
    public CustomerExtension Extension { get; set; }

    [Required]
    public string Value { get; set; }
}

然而，这给了我一把钥匙将丢失的错误。 \\ tSystem.Data.Entity.Edm.EdmEntityType：的EntityType'CustomerExtensionValue没有定义键。定义此的EntityType关键。

我知道我可以定义两个拿着引用的实体类型的主键属性。是Visual Studio中没有足够的智慧用​​在自己的主键？

I'm know I could define two more attributes holding the primary keys of the referenced entity types. Is Visual Studio not smart enough to use their primary keys on his own?

推荐答案

主键始终必须通过实体类标量属性进行定义。你不能单靠导航属性指的PK。在你的模型像这样的定义是必需的：

Primary keys always must be defined by scalar properties in the entity class. You cannot refer to the PKs by navigation properties alone. In your model a definition like this is required:

public class CustomerExtensionValue {

    [Key, ForeignKey("Customer"), Column(Order = 0)]
    public int CustomerId { get; set; }

    [Key, ForeignKey("Extension"), Column(Order = 1)]
    public int ExtensionId { get; set; }

    public Customer Customer { get; set; }
    public CustomerExtension Extension { get; set; }

    [Required]
    public string Value { get; set; }
}

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