Rails 3:如何根据 Controller 的方法创建命名范围? [英] Rails 3: How to create a named scope based on Controller's method?

问题描述

在我的 ApplicationController 中，我有 demo_mode? 方法(当当前登录的用户类型为demo"时返回 true).

In my ApplicationController I have the demo_mode? method (which returns true when the currently logged in user type is "demo").

Post 模型有 publisher_id 字段，它指的是 Users 表.

Post model has the publisher_id field, which refers to Users table.

User 具有 user_type 字段，其可能的值之一是demo".

User has the user_type field, one of the possible values of which is "demo".

底线:帖子 p 是由演示"用户发布的，当且仅当:

Bottom line: post p was published by a "demo" user if and only if:

User.find(p.publisher_id).user_type == "demo"

我想创建一个命名范围 Post.relevant 它将返回:

I would like to create a named scope Post.relevant that will return:

• 演示"用户发布的所有帖子，如果 demo_mode?== 真
• 非演示"用户发布的所有帖子，如果 demo_mode?== 假

您将如何创建这样的命名范围?我应该将 demo_mode? 移到其他地方吗?

How would you create such a named scope ? Should I move demo_mode? to other place ?

推荐答案

使用 lambda 来创建动态范围，并将会话信息保留在模型之外:

Use a lambda to make a dynamic scope, and keep the session info out of the model:

在您的模型中:

class Post < ActiveRecord::Base
  scope :relevant, lambda {|demo_mode|
     joins(:publisher).
     where("publishers.user_type #{demo_mode ? '' : 'NOT'} LIKE 'demo'")
  }
end

然后在控制器中:

posts = Post.relevant(demo_mode?)

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