用户表中的数据示例
rails控制台中的预期结果， grandfather.grandchildren 及 grandmother.grandchildren 应返回相同的对象组：
grandfather = User.first
grandfather.grandchildren
=> #<ActiveRecord::Associations::CollectionProxy [#<User id: 5, name: "father's son", father_id: 3, mother_id: nil>, #<User id: 6, name: "uncle's son", father_id: 4, mother_id: nil>]>
grandmother = User.find(2)
grandmother.grandchildren
=> #<ActiveRecord::Associations::CollectionProxy [#<User id: 5, name: "father's son", father_id: 3, mother_id: nil>, #<User id: 6, name: "uncle's son", father_id: 4, mother_id: nil>]>这是我现在在user.rb模型中的关联。
has_many :children, ->(user) { unscope(:where).where("father_id = :id OR mother_id = :id", id: user.id) }, class_name: "User"
has_many :grandchildren, through: :children, source: :children
belongs_to :mother, class_name: "User", optional: true
belongs_to :father, class_name: "User", optional: true现在在rails控制台中输出：
irb(main):001:0> grandfather = User.first
(0.3ms) SELECT sqlite_version(*)
User Load (0.2ms) SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT ? [["LIMIT", 1]]
=> #<User id: 1, name: "grandfather", mother_id: nil, father_id: nil>
irb(main):002:0> grandfather.grandchildren
User Load (0.3ms) SELECT "users".* FROM "users" INNER JOIN "users" "children_grandchildren" ON "users"."user_id" = "children_grandchildren"."id" WHERE (father_id = 1 OR mother_id = 1) /* loading for inspect */ LIMIT ? [["LIMIT", 11]]
Traceback (most recent call last):
ActiveRecord::StatementInvalid (SQLite3::SQLException: ambiguous column name: father_id)
1条答案
按热度按时间snz8szmq1#
您无法通过祖父母的子女从祖父母那里获得孙辈，因为这意味着他们的父亲/母亲ID与祖父母相同，而不是通过孙辈父母：
您可以向孙辈关系添加可调用的，类似于
children，但这次提取祖父母子女ID，并使用in子句筛选与这些ID匹配的用户行及其父亲/母亲ID：