destroy query if table widget is removed

modules/grids/app/models/grids/widget.rb

@@ -34,5 +34,15 @@ module Grids
 
     belongs_to :grid
     serialize :options, Hash
+
+    after_destroy :execute_after_destroy_strategy
+
+    private
+
+    def execute_after_destroy_strategy
+      proc = Grids::Configuration.widget_strategy(grid, identifier).after_destroy
+
+      instance_exec(&proc)
+    end
   end
 end

modules/grids/lib/grids/configuration.rb

@@ -95,6 +95,10 @@ class Grids::Configuration
       (grid_classes || []).include?(grid)
     end
 
+    def widget_strategy(grid, identifier)
+      grid_register[grid.class.to_s].widget_strategy(identifier)
+    end
+
     def writable?(grid, user)
       grid_register[grid.class.to_s]&.writable?(grid, user)
     end
@@ -120,6 +124,18 @@ class Grids::Configuration
     end
   end
 
+  class WidgetStrategy
+    class << self
+      def after_destroy(proc = nil)
+        if proc
+          @after_destroy = proc
+        end
+
+        @after_destroy ||= -> {}
+      end
+    end
+  end
+
   class Registration
     class << self
       def grid_class(name_string = nil)
@@ -146,6 +162,16 @@ class Grids::Configuration
         @widgets
       end
 
+      def widget_strategy(widget_name, &block)
+        @widget_strategies ||= {}
+
+        if block_given?
+          @widget_strategies[widget_name.to_s] = Class.new(Grids::Configuration::WidgetStrategy, &block)
+        end
+
+        @widget_strategies[widget_name.to_s] ||= Grids::Configuration::WidgetStrategy
+      end
+
       def defaults(hash = nil)
         # This is called during code load, which
         # may not have the table available.

modules/grids/lib/grids/my_page_grid_registration.rb

@@ -13,6 +13,10 @@ module Grids
             'documents',
             'news'
 
+    widget_strategy 'work_packages_table' do
+      after_destroy -> { ::Query.find_by(id: options[:queryId])&.destroy }
+    end
+
     defaults(
       row_count: 7,
       column_count: 4,

modules/grids/spec/models/grids/my_page_spec.rb

@@ -31,18 +31,46 @@ require 'spec_helper'
 require_relative './shared_model'
 
 describe Grids::MyPage, type: :model do
-  let(:instance) { described_class.new }
+  let(:instance) { described_class.new(row_count: 5, column_count: 5) }
   let(:user) { FactoryBot.build_stubbed(:user) }
 
   it_behaves_like 'grid attributes'
 
   context 'attributes' do
-    let(:user) { FactoryBot.build_stubbed :user }
-
     it '#user' do
       instance.user = user
       expect(instance.user)
         .to eql user
     end
   end
+
+  context 'altering widgets' do
+    context 'when removing a work_packages_table widget' do
+      let(:user) { FactoryBot.create(:user) }
+      let(:query) do
+        FactoryBot.create(:query,
+                          user: user,
+                          hidden: true)
+      end
+
+      before do
+        widget = Grids::Widget.new(identifier: 'work_packages_table',
+                                   start_row: 1,
+                                   end_row: 2,
+                                   start_column: 1,
+                                   end_column: 2,
+                                   options: { queryId: query.id })
+
+        instance.widgets = [widget]
+        instance.save!
+      end
+
+      it 'removes the widget\'s query' do
+        instance.widgets = []
+
+        expect(Query.find_by(id: query.id))
+          .to be_nil
+      end
+    end
+  end
 end