两次参考模型编写迁移 [英] Write a migration with reference to a model twice

问题描述

我有一个消息模型(Message)，这个模型作为一个 userTo 和 userFrom，所以有两个对 User 的引用.我该如何编写迁移?我的用户模型是 User.

I have a message model (Message) and this models as a userTo and userFrom, so two references to User. How can i write the migration? My user model is User.

谢谢

推荐答案

在迁移中，为每种用户创建两个不同的列.例如:

In the migration, create two different columns for each kind of user. For example:

add_column :messages, :sender_id, :integer
add_column :messages, :receiver_id, :integer

然后在模型中，这就是将每一列映射到 User 类的逻辑发生的地方:

Then in the model, that's where the logic to map each column to the User class happens:

belongs_to :sender, :class_name => 'User'
belongs_to :receiver, :class_name => 'User'

当然，sender 和 receiver 使用你自己的话，但是 Rails 会自动将 sender 关联到 sender_id 列(和 receiver 的逻辑相同)

Of course, use your own words for sender and receiver, but Rails will automatically associate sender to the sender_id column (and the same logic for receiver)

然后您将能够与用户 user.sender 和 user.receiver 进行交互.

You will then be able to interact with both user user.sender and user.receiver.

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