Rails 3，has_many：through和：polymorphic - 我需要這樣做嗎？

Question

好吧，所以在這裏。我不知道我是否過於複雜，或者如果我對Rails還是個新手，我不瞭解基礎知識。我想在須藤代碼是這樣的：

User 
has_many projects as owner through relationship 
has_many projects as contributor through relationship 
has_many projects as follower through relationship 

Project 
has_one user as owner through relationship 
has_many users as followers through relationship 
has_many users as contributors through relationship 

Relationship 
belongs_to user 
belongs_to project 

然後我想有以下神奇的東西：

owner = Project.owner 
followers = Project.followers 
contributors = Project.contributors 

projects = User.projects 
myprojects = User.projects... (now I'm really not sure) 
followedProjects = ... 
contributingProjects = ... 

所以寫下來，我可以看到，是在另一個差距我瞭解這種模式。用戶可以扮演所有者，追隨者或貢獻者的角色，或者三者的任意組合。

在真正的代碼方面，我已經在這裏添加了什麼，我認爲是有關部分：

class User < ActiveRecord::Base 
    has_many :user_project_relationships, :as => :relateable, :class_name => "UserProjectRelationship" 
    has_many :projects, :as => :owner, :through => :relateable, :class_name => "Project", :source_type => :owner 
    has_many :projects, :as => :follower, :through => :relateable, :class_name => "Project", :source_type => :follower 
    has_many :projects, :as => :contributor, :through => :relateable, :class_name => "Project", :source_type => :contributor 
end 

class Project < ActiveRecord::Base 
    has_many :user_project_relationships, :as => :relateable, :class_name => "UserProjectRelationship" 
    has_one :user, :as => :owner, :through => :relateable, :class_name => "User" 
    has_many :users, :as => :followers, :through => :relateable, :source_type => :follower, :class_name => "User" 
    has_many :users, :as => :contributors, :through => :relateable, :source_type => :contributor, :class_name => "User" 
end 

class UserProjectRelationship < ActiveRecord::Base 
    belongs_to :user 
    belongs_to :project, :polymorphic => true 
end 

了關係模型的遷移：

class CreateUserProjectRelationships < ActiveRecord::Migration 
    def self.up 
    create_table :user_project_relationships do |t| 
     t.integer :relateable_id 
     t.string :relateable_type 
     t.integer :project_id 
     t.timestamps 
    end 
    add_index :user_project_relationships, [:relateable_id, :relateable_type], :name => :relateable 
    add_index :user_project_relationships, :project_id 
    end 

    def self.down 
    drop_table :user_project_relationships 
    end 
end 

目前我得到的像project.users的錯誤ActiveRecord::HasManyThroughAssociationNotFoundError: Could not find the association :relateable in model Project

我覺得我在這裏的荒野中真正得到我想要的東西，也許依靠神奇的導軌做比它更多的事情。任何關於最佳路徑的指導將不勝感激。

在此先感謝

史蒂夫

Answer 1

Rails可以做了很多，但我覺得不是你想使關係模型做太多。每個人都是不同的關係，所以我想盡量讓他們保持這種關係。

拆分成單獨的連接模式：

class User < ActiveRecord::Base 

    has_many :owned_projects, :class_name => "Project", :foreign_key => :owner_id 

    has_many :projects_followers 
    has_many :followed_projects, :class_name => "Project", :through => :projects_followers 

    has_many :projects_contributors 
    has_many :contributed_projects, :class_name => "Project", :through => :projects_contributors 

end 

class Project < ActiveRecord::Base 
    belongs_to :owner 

    has_many :projects_followers 
    has_many :followers, :class_name => "User", :through => :projects_followers 


    has_many :projects_contributors, :foreign_key => :contributor_id 
    has_many :contributors, :class_name => "User", :through => :projects_contributors 

end 

class ProjectsFollowers < ActiveRecord::Base 
    belongs_to :user 
    belongs_to :project 
end 

class ProjectsContributors < ActiveRecord::Base 
    belongs_to :user 
    belongs_to :project 
end 

應該是更接近你想要的東西很多。然後，您可以做確實

project.owner 
project.followers 
project.contributors 

和

user.owned_projects 
user.followed_projects 
user.contributed_projects 

應該要麼工作，或讓你八九不離十。

我認爲你的混淆來自於嘗試創造一種多態關係，我認爲這不是我們想要的。 AFAI grok，多態關係的用例是當你想讓1個模型與的任何數量的其他模型相關時。情況並非如此，因爲您有兩種模型，它們之間有三種不同類型的關係。