可选实体框架复杂类型的必需属性 [英] Required Properties on optional Entity Framework Complex Types

问题描述

我想在实体框架的复杂类型中定义 [必需] 属性。例如，我有一个 Customer 实体和一个可选的 Address 。地址实体具有必需的 PostCode 属性。

I want to define [Required] attributes on a Complex Type in Entity Framework. For example, I have a Customer entity with an optional Address. The Address entity has a required PostCode property.

[ComplexType]
public class Address {
    public string Address1 { get; set; }
    [Required]
    public string PostCode { get; set; }
}

public class Customer {
    public int CustomerId {get;set;}
    public Address Address {get;set;}
}

我不想将我的Complex类型存储为单独的实体（我实际上并没有使用Address，这只是问题的简单说明）。我不能将Customer.Address保留为空，因为这样会产生错误：

I do NOT want to store my Complex type as a separate entity (I'm not actually using Address, this just an easy illustration of the problem). I cannot leave Customer.Address null, because this gives the error:

不可空成员的空值。成员：地址。

Null value for non-nullable member. Member: 'Address'.

如果我提供了一个空的Address实体，则由于Required属性而使PostCode字段的验证失败。

If I supply an empty Address entity, the validation fails on the PostCode field because of the Required attribute.

有什么方法可以实现？我正在使用EF5 / NET4.5。

Is there any way to achieve this? I'm using EF5/NET4.5.

推荐答案

使用复杂类型是不可能的。如果希望它可以为空，则需要创建一个地址实体。

It's not possible with a complex type. You'll need to create an Address entity if you want it to be nullable.

EF对复杂类型所做的操作是将属性映射到同一张表-

What EF will do with a complex type is map the properties to the same table - which it sounds like you've intended.

因此，您的示例架构如下所示：

Because of that - your schema for your example would look like this:

带有非-nullable列的Address_PostCode，因为它在数据库中无效，因此没有对象没有地址和邮政编码的情况下，EF无法创建行。

With a non-nullable column for Address_PostCode, since it's not valid in the database there's not a way for EF to create the row, without your object having an address, and a postcode.

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