[英]Modeling Favorites
我想在我的User
和Link
模型中添加一個Favorite
模型。
商業邏輯
我對如何建模這種關聯感到困惑,一旦模型到位,我將如何創建用戶喜好?
class User < ActiveRecord::Base
has_many :links
has_many :favorites
end
class Link < ActiveRecord::Base
belongs_to :user
#can be favorited by multiple users
end
class Favorite < ActiveRecord::Base
belongs_to :user
belongs_to :link
end
以下數據模型如何:
class User < ActiveRecord::Base
has_many :links
has_many :favorites, :dependent => :destroy
has_many :favorite_links, :through => :favorites, :source => :link
end
class Link < ActiveRecord::Base
belongs_to :user
has_many :favorites, :dependent => :destroy
has_many :favorited, :through => :favorites, :source => :user
end
class Favorite < ActiveRecord::Base
belongs_to :user
belongs_to :link
end
由於User
已經有一個名為links
的關聯,而Link
已經有一個名為users
,因此我們不能對has_many :through
關聯使用相同的名稱(例如, User has_many :links, :through => :favorites
不起作用)。 因此,我們發明了一個新的關聯名稱,並幫助Rails知道通過source
屬性從中間關聯加載的關聯。
這是使用此關聯的一些偽代碼:
# Some users
user1 = User.create :name => "User1"
user2 = User.create :name => "User2"
# They create some links
link1_1 = user1.links.create :url => "http://link1_1"
link1_2 = user1.links.create :url => "http://link1_2"
link2_1 = user2.links.create :url => "http://link2_1"
link2_2 = user2.links.create :url => "http://link2_2"
# User1 favorites User2's first link
user1.favorites.create :link => link2_1
# User2 favorites both of User1's links
user2.favorites.create :link => link1_1
user2.favorites.create :link => link1_2
user1.links => [link1_1, link1_2]
user1.favorite_links => [link2_1]
user2.links => [link2_1, link2_2]
user2.favorite_links => [link1_1, link1_2]
link1_1.favorited => [user2]
link2_1.destroy
user1.favorite_links => []
user2.links => [link2_2]
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