我需要一个类变量还是一个实例变量？

Question

我目前有一个名为owner_id的ActiveRecord模型“团队”。

owner_id数据只是临时的，一旦after_create被调用，它将是多余的。

我想删除'owner_id'列并整理它，但保持功能正常。我怎样才能做到这一点？

有关背景：

class Team < ActiveRecord::Base 
    attr_accessible :name, :owner_id, :team_id 
    has_many :team_memberships, :dependent => :destroy 
    has_many :users, through: :team_memberships 
    accepts_nested_attributes_for :team_memberships 

    after_create :create_team_membership 

    private 

    def create_team_membership 
    TeamMembership.create(
     :user_id => self.owner_id, 
     :team_id => self.id, 
     :roles => "site_admin") 
    end 
end 

Answer 1

您应该能够添加attr_accessor，继续没有数据库列例如分配owner_id属性Team.new(:owner_id => 7)

class Team < ActiveRecord::Base 
    attr_accessor :owner_id 
end 

您还可以避免明确地分配team_id，如果你想：

class Team < ActiveRecord::Base 
    def create_team_membership 
    team_memberships.create(:user_id => owner_id, :roles => "site_admin") 
    end 
end