修改 has_many 的行为还是使用范围? [英] Modify the behavior of has_many or use scope?

问题描述

我有一个看起来像这样的类:

I have a class that looks something like this:

class User < ActiveRecord:Base
  has_many :users_companies
  has_many :companies, :through => :users_companies
end

对于普通用户，我希望 user.companies 引用标准关联方法，但是当用户是管理员时，我希望 User.all (即，管理员可以访问所有公司).我能想到的最简单的实现方法(以及我过去一直在做的事情)是在 Company 类上使用范围，例如:

For plain users, I'd like user.companies to refer to the standard association method, but when a user is an admin, I want User.all (i.e., admins have access to all companies). The simplest way I can think of to implement this (and what I've always done in the past) is use a scope on the Company class, such as:

scope :accessible_by, lambda { |user| ... }

唯一的问题是这感觉不对.而不是编写包含以下内容的控制器操作:

The only problem is that this just doesn't feel right. Instead of writing a controller action that includes:

  @companies = Company.accessible_by(current_user)

我觉得写起来更舒服

  @companies = current_user.companies

是否有一种好方法可以覆盖 User#companies 方法以适应这种行为?或者，我应该对在公司上使用范围感到满意吗?

Is there a good way to override the User#companies method to accommodate this kind of behavior? Or, should I be happy with using a scope on Company?

推荐答案

我正在努力解决一个类似的问题.我可以设计的唯一可接受的解决方案是 关联扩展，它覆盖管理员用户的查询和通过普通用户的查询，不受干扰.

I'm wrestling with a similar problem. The only acceptable solution I can devise is an association extension, which overrides the query for admin users and passes normal users' queries, unmolested.

# this works for me in rails 3.1
class User < ActiveRecord:Base
  has_many :users_companies
  has_many :companies, :through => :users_companies do
    def visible
      if proxy_association.owner.admin?
        UsersCompany.scoped
      else
        self
      end
    end
  end
end

User.where(:admin => true).first.companies.visible == UsersCompany.all

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