具有相同关系的多个实例的Rails关联

您可以显式地这样做 class_name 在…上 belongs_to 和 has_many 和 foreign_key 在…上 你有很多

class Approval < ApplicationModel
  belongs_to :manager, class_name: 'Employee'
  belongs_to :subordinate, class_name: 'Employee'
end

class Employee < ApplicationModel
  has_many :manager_approvals, foreign_key: :manager_id, class_name: 'Approval'
  has_many :subordinate_approvals, foreign_key: :subordinate_id, class_name: 'Approval'
end

• has many
• belongs to

1=>添加迁移添加 manager_id Employee

rails g migration add_manager_id_to_employee manager_id:integer

class Employee < ApplicationRecord
  belongs_to :manager, optional: true
  has_many : subordinates, :class_name => "Employee", :foreign_key => "manager_id"
end

3=>

class Approval < ApplicationRecord
  belongs_to :employee
  has_one :manager, { where("employees.manager_id= nil ") }
  has_one :subordinate, { where("employees.manager_id= self.employee_id") }
end