在我的应用程序中,用户可以关注许多用户,并且可以跟随许多用户.
我尝试使用has_and_belongs_to_many关联对此进行建模
我尝试使用has_and_belongs_to_many关联对此进行建模
class User < ActiveRecord::Base has_and_belongs_to_many :followers,class_name: "User",foreign_key: "followee_id",join_table: "followees_followers" has_and_belongs_to_many :followees,foreign_key: "follower_id",join_table: "followees_followers" end
另外,我为连接表创建了一个迁移,如下所示：
class FolloweesFollowers < ActiveRecord::Migration
def up
create_table 'followees_followers',:id => false do |t|
t.column :followee_id,:integer
t.column :follower_id,:integer
end
end
def down
drop_table 'followees_followers'
end
end
当我尝试访问用户的关注者(User.first.followers)时,它会抛出一个错误：
sqlException: no such column: followees_followers.user_id: SELECT "users".* FROM "users" INNER JOIN "followees_followers" ON "users"."id" = "followees_followers"."user_id" WHERE "followees_followers"."followee_id" = 1
我不明白为什么要访问followees_followers.user_id.我错过了什么吗？
解决方法
设置多对多自联接时,：foreign_key和
:association_foreign_key选项很有用.
class User < ActiveRecord::Base has_and_belongs_to_many :followers,join_table: "followees_followers",association_foreign_key: "follower_id" has_and_belongs_to_many :followees,association_foreign_key: "followee_id" end