在Rails 3上所有者过滤的模型对象 [英] Owner-filtered model objects on Rails 3

问题描述

我需要对ActiveRecord模型进行一些过滤，我想按owner_id过滤所有模型对象.我需要的基本上是ActiveRecord的default_scope.

I need to do some filtering on my ActiveRecord models, I want to filter all my model objects by owner_id. The thing I need is basically the default_scope for ActiveRecord.

但是我需要通过一个会话变量进行过滤，该变量无法从模型中访问.我已经阅读了一些解决方案，但是没有一个可行的方法，基本上任何一个都说你声明default_scope时可以使用会话.

But I need to filter by a session variable, which is not accessible from the model. I've read some solutions, but none works, basically any of them says that you can use session when declaring default_scope.

这是我对范围的声明:

class MyModel < ActiveRecord::Base
    default_scope { where(:owner_id => session[:user_id]) }
    ...
end

简单，对吧?但是它不能说方法会话不存在.

Simple, right?. But it fails saying that method session does not exists.

希望可以为您提供帮助

推荐答案

模型中的会话对象被认为是不好的做法，相反，您应该向User类中添加一个类属性，该属性是在around_filter中设置的您的ApplicationController，基于current_user

Session objects in the Model are considered bad practice, instead you should add a class attribute to the User class, which you set in an around_filter in your ApplicationController, based on the current_user

class User < ActiveRecord::Base

    #same as below, but not thread safe
    cattr_accessible :current_id

    #OR

    #this is thread safe
    def self.current_id=(id)
      Thread.current[:client_id] = id
    end

    def self.current_id
      Thread.current[:client_id]
    end  

end

，然后在您的ApplicationController中执行:

class ApplicationController < ActionController::Base
    around_filter :scope_current_user  

    def :scope_current_user
        User.current_id = current_user.id
    yield
    ensure
        #avoids issues when an exception is raised, to clear the current_id
        User.current_id = nil       
    end
end

现在，在您的MyModel中，您可以执行以下操作:

And now in your MyModel you can do the following:

default_scope where( owner_id: User.current_id ) #notice you access the current_id as a class attribute

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