Question

有模型：member（id，project_id，user_id），project（id），user（id），somemodel（id，project_id，user_id）。

成员belongs_to：project，belongs_to：user
somemodel belongs_to：project，belongs_to：user

我希望删除成员时删除somemodel（其中project_id和user_id与该成员相同）也会被删除。怎么做？

为此，我希望将/** * Run the migrations. * * @return void */ public function up() { /** * Drop column type in products table */ Schema::table('products', function (Blueprint $table) { $table->dropColumn('type'); }); /** * Create column product_type in products table */ Schema::table('products', function (Blueprint $table) { $table->integer('product_type_id')->unsigned()->after('price'); $table->foreign('product_type_id')->references('id')->on('product_types')->onDelete('cascade'); }); } /** * Reverse the migrations. * * @return void */ public function down() { /** * Drop column product_type_id in products table */ Schema::table('products', function (Blueprint $table) { $table->dropForeign('product_type_id'); $table->dropColumn('product_type_id'); }); /** * Re-create column type in products table */ Schema::table('products', function (Blueprint $table) { $table->string('type')->after('price'); }); }添加到成员中，但我不知道在成员类中提供has_many :somemodels, dependent: :destroy的正确参数。仅has_many :somemodels单独尝试通过member_id搜索somemodel时没有工作，而some_odels表中不存在，因此发生has_many :somemodels, dependent: :destroy错误。

将no column添加到会员中的权利是什么？

Answer 1

另一种方法是为此特定关系创建:through关联，然后将其设置为dependent: :destroy。我认为它的结构如下：

class Member < ActiveRecord::Base

  belongs_to :user
  belongs_to :project

  has_many :some_models, ->(member) { where(user_id: member.user_id) },
                         through: :project,
                         dependent: :destroy
end

我还没有对它进行过测试，但就我所见，这似乎是正确的。

Answer 2

我认为你应该向Member模型添加一个after_destroy回调：

# In member model
class Member < ApplicationRecord
    after_destroy :also_destroy_somemodel
    ...

   def also_destroy_somemodel
       # Fast, use in case somemodel dont have any callbacks
       Somemodel.where(project_id: project_id, user_id: user_id).delete_all

       # Or
       # Slow, use in case somemodel has callback(s)
       # Somemodel.where(project_id: project_id, user_id: user_id).each &:destroy
   end
end

希望它有所帮助。

如何用has_many摧毁......

2 个答案: