Rails 自身的many to many关系 self has_many
程序员文章站
2022-05-19 23:23:42
...
简单点的
稍微不同的一个版本
自身referential而且,还有两个名字,例如tiwtter你的follower, 叫friend
Spec测试部分
Model设置
#注意外键在person上people: id; name; whatever-you-need friendships: id; person_id; friend_id class Person < ActiveRecord::Base has_many :friendships, :foreign_key => "person_id", :class_name => "Friendship" has_many :friends, :through => :friendships end class Friendship < ActiveRecord::Base belongs_to :person, :foreign_key => "person_id", :class_name => "Person" belongs_to :friend, :foreign_key => "friend_id", :class_name => "Person" end
稍微不同的一个版本
ActiveRecord::Schema.define(:version => 20100410040453) do create_table "people", :force => true do |t| t.string "name" t.string "sex" t.integer "father_id" t.integer "mother_id" t.datetime "created_at" t.datetime "updated_at" end end
#这里就要看source的应用,是用来关联belongs_to的 class Person < ActiveRecord::Base self.inheritance_column = "sex" belongs_to :father, :class_name => "Person" belongs_to :mother, :class_name => "Person" end class Male < Person has_many :children, :class_name => "Person", :foreign_key => :father_id has_many :babymommas, :through => :children, :source => :mother, :uniq => true end class Female < Person has_many :children, :class_name => "Person", :foreign_key => :mother_id has_many :babydaddies, :through => :children, :source => :father, :uniq => true end
自身referential而且,还有两个名字,例如tiwtter你的follower, 叫friend
create_table :users do |t| t.column :login, :string, :null => false end create_table :relationships, :id => false do |t| t.column "user_id", :integer, :null => false t.column "buddy_id", :integer, :null => false end
Spec测试部分
describe User do before :each do %w(u v w).each do |x| eval "@#{x} = User.new; @#{x}.login = '#{x}'; @#{x}.save" end end it "can be linked with another user" do @u.linked_to << @v @u.linked_to.should include(@v) u2 = User.find_by_id @u.id u2.linked_to.should include(@v) end it "can find users that linked to it" do @u.linked_to << @v @v.linked_from.should include(@u) end it "can see friends of its friends" do @u.linked_to << @v @v.linked_to << @w @u.linked_to[0].linked_to.should include(@w) @w.linked_from[0].linked_from.should include(@u) end it "has a list of all users linked to and from it" do @u.linked_to << @v @v.linked_to << @w @v.linked.should include(@u) @v.linked.should include(@w) end end
Model设置
class Relationship < ActiveRecord::Base belongs_to :user, :class_name => 'User', :foreign_key => 'user_id' belongs_to :buddy, :class_name => 'User', :foreign_key => 'buddy_id' end class User < ActiveRecord::Base has_many :relations_to, :foreign_key => 'user_id', :class_name => 'Relationship' has_many :relations_from, :foreign_key => 'buddy_id', :class_name => 'Relationship' has_many :linked_to, :through => :relations_to, :source => :buddy has_many :linked_from, :through => :relations_from, :source => :user end
select user_id, buddy_id from relationships union select buddy_id, user_id from relationships def linked User.find_by_sql " select * from users where id in ( select buddy_id from buddies where user_id = #{id})" end