如何使用依赖::在rails中销毁？

Question

我有2个型号,如下所述.

class EmpGroup < ActiveRecord::Base
  belongs_to :user
  has_many :emp_group_members, dependent: :destroy
end

和

class EmpGroupMember < ActiveRecord::Base
  belongs_to :emp_group
  belongs_to :user
end

现在问题是每当我试图销毁一个组然后我收到如下错误.

PG::ForeignKeyViolation: ERROR:  update or delete on table "emp_groups" violates foreign key constraint "fk_rails_bd68440021" on table "emp_group_members"
DETAIL:  Key (id)=(1) is still referenced from table "emp_group_members".

我错过了什么？

Answer 1

将级联删除添加到您的EmpGroup模型:

class EmpGroup < ActiveRecord::Base
   has_many :emp_group_members, :dependent => :delete_all
end

要么

你在打电话delete吗？你应该打个电话destroy.使用.destroy

Answer 2

:dependent是belongs_to关联中可用的选项之一

If you set the :dependent option to:

:destroy, when the object is destroyed, destroy will be called on its associated objects.
:delete, when the object is destroyed, all its associated objects will be deleted directly from the database without calling their destroy method.

Additionally, objects will be destroyed if they're associated with dependent: :destroy, and deleted if they're associated with dependent: :删除所有.

在has_many关联中:

:destroy causes all the associated objects to also be destroyed
:delete_all causes all the associated objects to be deleted directly from the database (so callbacks will not execute)

你可以试试

 emp_member_1= @emp_group.emp_group_members.first
 ##delete associated record
 @emp_group.emp_group_members.delete(emp_member_1)

Answer 3

新语法：

class EmpGroup < ActiveRecord::Base
   has_many :emp_group_members, dependent: :destroy
end