Rails模型和独特的组合 [英] Rails Models and unique combinations

问题描述

我有一个Rails应用程序，其中有一个名为friendrequests的表.看起来像这样:

I have a Rails app which has a table called friendrequests. It looks like this:

user1_id:integer user2_id:integer hasaccepted:boolean

我正在创建一个添加朋友的选项，但是一个Friendrequest只能发送一次.因此，数据库的数据中不能包含这样的内容:

I'm creating an option to add friends, but a friendrequest can only be send once. So you cannot have something like this in the database's data:

user1_id | user2_id | hasaccepted
       1 |        2 |       false
       1 |        2 |       false

或

user1_id | user2_id | hasaccepted
       1 |        2 |       false
       2 |        1 |       false

user1_id/user2_id组合必须是唯一的，而不是列本身，因此这是可能的:

The user1_id/user2_id combination must be unique, not the columns themselves, so this would be possible:

user1_id | user2_id | hasaccepted
       1 |        2 |       false
       1 |        3 |       false

是否可以在模型中定义它?我该怎么办?

Is it possible to define this in a model? How can I do this?

推荐答案

对于第一种情况，在您的FriendRequest模型中，使用validates_uniqueness_of(:user1_id, :scope => :user2_id).您可能还需要相反的操作.对于第二种情况，我将覆盖FriendRequest中的#validate并在那里进行检查(请参见 API文档，详细了解该方法的执行方式.

For the first case, in your FriendRequest model, use validates_uniqueness_of(:user1_id, :scope => :user2_id). You might also need the reverse. For the second case I'd override #validate in FriendRequest and do a check in there (see the API docs for details on how the method should perform).

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