NHibernate使用联接表上的数据映射多对多关系 [英] NHibernate Mapping a Many to Many with Data on Join Table

问题描述

我有一个User表和一个Address表.它们通过联接表连接.映射很简单，但是我想在连接表上显示一些数据，这些数据想显示在地址表上.

I have a User table and an Address table. They are connected by a join table. The mapping for that is straight forward, but I have some data on the join table that I would like to show up on the Address table.

也许还有更好的方法进行设置，我愿意征求建议.

There may be a better way to set this up also, which I'm open to suggestions for.

这是表结构.

CREATE TABLE [dbo].[User]
(
    [Id] INT NOT NULL IDENTITY PRIMARY KEY,
    ...
)

CREATE TABLE [dbo].[Address]
(
    [Id] INT NOT NULL IDENTITY PRIMARY KEY,
    ...
)

CREATE TABLE [dbo].[AddressType]
(
    [Id] INT NOT NULL IDENTITY PRIMARY KEY,
    [Name] NVARCHAR( 10 ) NOT NULL, -- Values: 'Shipping', 'Billing'
    ...
)

CREATE TABLE [dbo].[UserAddress]
(
    [UserId] INT NOT NULL FOREIGN KEY REFERENCES [dbo].[User]( [Id] ),
    [AddressId] INT NOT NULL FOREIGN KEY REFERENCES [dbo].[Address]( [Id] ),
    [AddressTypeId] INT NOT NULL FOREIGN KEY REFERENCES [dbo].[AddressType]( [Id] ),
    ...
)

我想要的是在用户对象上具有送货地址和账单地址的列表.我将如何映射?我正在使用Fluent NHibernate进行映射.

What I want is to have a list of shipping and billing addresses on the user object. How would I map that? I'm using Fluent NHibernate for mapping.

我最初是从两个联接表BillingAddress和ShippingAddress开始的，这两个联接表只是User和Address表之间的联接.这可以很好地工作，但是然后有两个表具有完全相同的结构，可以完成相同的操作，而且看起来似乎不正确.

I originally started out with two join tables, BillingAddress and ShippingAddress, that were just joins between the User and Address tables. This would work fine, but then there are 2 tables with the exact same structure that do the same thing, and it just didn't seem right.

推荐答案

如果您的联接表(例如UserAddress)不仅仅是一对外键，并且其中具有元数据(例如AddressType)，则需要映射关联一对多的一对关系，并将关联表示为对象模型中的一个实体.例如:

If your join table (e.g. UserAddress) is more than just a pair of foreign keys and has metadata (e.g. AddressType) in it, you need to map the association as a pair of one-to-many relationships and represent the association as an entity in your object model. For example:

User <has-many> AddressAssociation <references> Address

AddressAssociation将把AddressType作为属性. (基本上，我是将UserAddress重命名为AddressAssociation，以使其听起来更像是域实体.)User to AddressAssociation是User-> AddressAssociation中的一对多对象.引用是AddressAssociation和Address之间的多对一.

AddressAssociation would have the AddressType as a property. (Basically I'm renaming UserAddress to AddressAssociation to make it sound more like a domain entity.) User to AddressAssociation is a one-to-many from User->AddressAssociation. The references is a many-to-one between AddressAssociation and Address.

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