在Rails中命名多對多關係

Question

如何在Rails 3.2中創建以下模型？項目可以有1個以上的所有者和1個以上的用戶。他們都是Person類的實例。我想過has_and_belongs_to_many，但我不知道如何爲每個項目處理兩個單獨的人員集合。

Answer 1

你需要一個連接模型來表示每個has-and-belongs-to-many關係，你所描述的here訪問使用has-many-through：

class ProjectOwnerLink < ActiveRecord::Base 
    belongs_to :project 
    belongs_to :owner, class_name: 'Person' 
end 

class ProjectUserLink < ActiveRecord::Base 
    belongs_to :project 
    belongs_to :user, class_name: 'Person' 
end 

class Project < ActiveRecord::Base 
    has_many :project_owner_links 
    has_many :owners, :through => :project_owner_links 
    has_many :project_user_links 
    has_many :users, :through => :project_user_links 
end 

class Person < ActiveRecord::Base 
    has_many :project_owner_links 
    has_many :owned_projects, :through => :project_owner_links, :source => :project 
    has_many :project_user_links 
    has_many :used_projects, :through => :project_user_links, :source => :project 
end 

Answer 2

您可以定義的關係成立的種類另一種模型Participation，即用戶的角色。 （未測試的）代碼：

class Project < ActiveRecord::Base 
    has_many :participations 
    has_many :users, :through => :participations 

    def with_role(role) 
    includes(:participations).where('participation.role = ?', role) 
    end 

    def owners 
    users.with_role('owner') 
    end 

    def participants 
    users.with_role('participant') 
    end 
end 

class User < ActiveRecord::Base 
    has_many :participations 
    has_many :projects, :through => :participations 

    def with_role(role) 
    includes(:participations).where('participation.role = ?', role) 
    end 

    def projects_owned 
    projects.with_role('owner') 
    end 

    def projects_participating_in 
    projects.with_role('participant') 
    end 
end 

class Participation < ActiveRecord::Base 
    # has an attribute 'role' 

    belongs_to :project 
    belongs_to :user 
end 

Answer 3

下面是演示應用程序。

https://github.com/diatmpravin/habtm-demo.git

請看看，讓我知道，如果你有任何問題嗎？