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我有一个场景，我需要使用 Entity Framework 4.1 Code-First 将一个类的两个属性绑定到另一个类。（作为参考，Upshot.js 正在使用此模型以在使用 Knockout.js 2.1 的单页应用程序中使用）

通常，我会执行以下操作：

    public class Person
    {
        [Key]
        public int PersonId { get; set; }

        public string FirstName { get; set; }
        public string LastName { get; set; }

        public Address HomeAddress { get; set; }
        public Address OfficeAddress { get; set; } 
    }

    public class Address
    {
        [Key]
        public int AddressId { get; set; }

        public string StreetAddress { get; set; }
        public string City { get; set; }
        public string State { get; set; }
        public string ZipCode { get; set; }
    }

这允许 HomeAddress 和 OfficeAddress 都引用 Address 类的实例。

请注意，这不是我的真实数据模型。它仅用于说明目的。在现实生活中，我可能会使用 ICollection。不幸的是，对于这种特殊情况是不可行的，我确实需要维护从一个类到另一个类的多个引用。

In this particular scenario, it is also possible for a person to exist without any addresses defined. It is also possible for addresses to exist without a person. (As mentioned, this data model is just an example.)

While this compiles correctly, and I can even create and save data, upshot complains bitterly when it attempted to use this model.

It gives an (inner) exception like the following:

{"Unable to retrieve association information for association 'KnockoutTest.Models.Person_HomeAddress'. Only models that include foreign key information are supported. See Entity Framework documentation for details on creating models that include foreign key information."}

So... I attempted to set the Foreign Key information on the DbContext class like

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Person>()
    .HasOptional(m => m.HomeAddress);

    modelBuilder.Entity<Person>()
    .HasOptional(m => m.OfficeAddress);
}

No joy! This still gave me the same exception.

I am not sure how to set up the foreign key association so that multiple properties on one class can reference another class--at least not in a way that upshot will be pleased and stop complaining for a while.

What am I doing wrong, and how do I fix it?

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1 回答 1

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您只需在模型类中引入标量外键属性：

public class Person
{
    [Key]
    public int PersonId { get; set; }

    public string FirstName { get; set; }
    public string LastName { get; set; }

    [ForeignKey("HomeAddress")]
    public int? HomeAddressId { get; set; }
    public Address HomeAddress { get; set; }

    [ForeignKey("OfficeAddress")]
    public int? OfficeAddressId { get; set; } 
    public Address OfficeAddress { get; set; } 
}

这些属性必须是可空的 ( int?)，因为您的关系是可选的（人可以在没有地址的情况下存在）。

于 2012-05-19T11:55:38.610 回答