重命名多对多关联

Question

我有3种型号: User,Artist和Following

User - Artist协会是多对多的Following.

Following表有user_id和artist_id字段.

如何设置此关联,以便我可以使用:

User.find(123).followed_artists
Artist.find(234).followers

因为我迷失了所有这些参数,class_name,source,foreign_key.

Answer 1

让我们说你有多次设置的磨机运行:

class User
  has_many :followings
  has_many :artists, through: :following
end

class Following
  belongs_to :user
  belongs_to :artist
end

class Artists
  has_many :followings
  has_many :users, through: :following
end

请耐心等待,到目前为止,ActiveRecord可以自行弄清楚在哪里through只需通过演绎来寻找关系的目标.

如果我们想为artists和users关系使用不同的名称,我们只需告诉活动记录使用以下关联:

class User
  has_many :followings
  has_many :followed_artists, through: :following, source: :artist
end

class Following
  belongs_to :user
  belongs_to :artist
end

class Artists
  has_many :followings
  has_many :followers, through: :following, source: :user
end

只要ActiveRecord可以从连接表上的关系名称中推断出它,我们就不必使用class_name或foreign_key选项.

但是,如果不是这种情况,则必须在连接表上指定它.让我们说一些赶时髦的人开始在你的应用程序中捣蛋:

class Following
  belongs_to :user, class_name: 'Persona', foreign_key: 'persona_id'
  belongs_to :artist, class_name: 'Artiste', foreign_key: 'artiste_id'
end

如果连接模型的关系名称不是"常规",则同样适用.

class User
  has_many :artist_followings, class_name: 'Following'
  has_many :followed_artists, through: :artist_followings, 
                              source: :artist
end

class Following
  belongs_to :user
  belongs_to :artist
end