Fix MilestonesFinder to pass relations to scope

Instead of querying relations into ids we just pass them to the model
scope because the scope supports it now.

Also changes other calls to `Milestone.for_projects_and_groups`

Author: engwan

app/controllers/projects/milestones_controller.rb

@@ -144,7 +144,7 @@ def milestone_params
 
   def search_params
     if request.format.json? && project_group && can?(current_user, :read_group, project_group)
-      groups = project_group.self_and_ancestors_ids
+      groups = project_group.self_and_ancestors.select(:id)
     end
 
     params.permit(:state).merge(project_ids: @project.id, group_ids: groups)

app/finders/milestones_finder.rb

@@ -3,26 +3,22 @@
 # Search for milestones
 #
 # params - Hash
-#   project_ids: Array of project ids or single project id.
-#   group_ids: Array of group ids or single group id.
+#   project_ids: Array of project ids or single project id or ActiveRecord relation.
+#   group_ids: Array of group ids or single group id or ActiveRecord relation.
 #   order - Orders by field default due date asc.
 #   title - filter by title.
 #   state - filters by state.
 
 class MilestonesFinder
   include FinderMethods
 
-  attr_reader :params, :project_ids, :group_ids
+  attr_reader :params
 
   def initialize(params = {})
-    @project_ids = Array(params[:project_ids])
-    @group_ids = Array(params[:group_ids])
     @params = params
   end
 
   def execute
-    return Milestone.none if project_ids.empty? && group_ids.empty?
-
     items = Milestone.all
     items = by_groups_and_projects(items)
     items = by_title(items)
@@ -34,7 +30,7 @@ def execute
   private
 
   def by_groups_and_projects(items)
-    items.for_projects_and_groups(project_ids, group_ids)
+    items.for_projects_and_groups(params[:project_ids], params[:group_ids])
   end
 
   # rubocop: disable CodeReuse/ActiveRecord

app/models/milestone.rb

@@ -45,7 +45,7 @@ class Milestone < ActiveRecord::Base
     groups = groups.compact if groups.is_a? Array
     groups = [] if groups.nil?
 
-    where(project: projects).or(where(group: groups))
+    where(project_id: projects).or(where(group_id: groups))
   end
 
   scope :order_by_name_asc, -> { order(Arel::Nodes::Ascending.new(arel_table[:title].lower)) }
@@ -191,7 +191,7 @@ def self.states_count(projects, groups = nil)
     return STATE_COUNT_HASH unless projects || groups
 
     counts = Milestone
-               .for_projects_and_groups(projects&.map(&:id), groups&.map(&:id))
+               .for_projects_and_groups(projects, groups)
                .reorder(nil)
                .group(:state)
                .count
@@ -275,8 +275,7 @@ def uniqueness_of_title
     if project
       relation = Milestone.for_projects_and_groups([project_id], [project.group&.id])
     elsif group
-      project_ids = group.projects.map(&:id)
-      relation = Milestone.for_projects_and_groups(project_ids, [group.id])
+      relation = Milestone.for_projects_and_groups(group.projects.select(:id), [group.id])
     end
 
     title_exists = relation.find_by_title(title)

app/services/issuable_base_service.rb

@@ -61,10 +61,10 @@ def filter_milestone
     return unless milestone_id
 
     params[:milestone_id] = '' if milestone_id == IssuableFinder::NONE
-    group_ids = project.group&.self_and_ancestors&.pluck(:id)
+    groups = project.group&.self_and_ancestors&.select(:id)
 
     milestone =
-      Milestone.for_projects_and_groups([project.id], group_ids).find_by_id(milestone_id)
+      Milestone.for_projects_and_groups([project.id], groups).find_by_id(milestone_id)
 
     params[:milestone_id] = '' unless milestone
   end

app/services/milestones/promote_service.rb

@@ -82,11 +82,9 @@ def destroy_old_milestones(milestone)
     end
     # rubocop: enable CodeReuse/ActiveRecord
 
-    # rubocop: disable CodeReuse/ActiveRecord
     def group_project_ids
-      @group_project_ids ||= group.projects.pluck(:id)
+      group.projects.select(:id)
     end
-    # rubocop: enable CodeReuse/ActiveRecord
 
     def raise_error(message)
       raise PromoteMilestoneError, "Promotion failed - #{message}"

app/services/projects/autocomplete_service.rb

@@ -14,7 +14,7 @@ def milestones
         order: { due_date: :asc, title: :asc }
       }
 
-      finder_params[:group_ids] = @project.group.self_and_ancestors_ids if @project.group
+      finder_params[:group_ids] = @project.group.self_and_ancestors.select(:id) if @project.group
 
       MilestonesFinder.new(finder_params).execute.select([:iid, :title])
     end

changelogs/unreleased/47988-improve-milestone-queries-with-subqueries.yml

@@ -0,0 +1,5 @@
+---
+title: Improve milestone queries using subqueries instead of separate queries for ids
+merge_request: 24325
+author:
+type: performance

lib/banzai/filter/milestone_reference_filter.rb

@@ -101,9 +101,9 @@ def milestone_finder_params(parent, find_by_iid)
 
       def self_and_ancestors_ids(parent)
         if group_context?(parent)
-          parent.self_and_ancestors_ids
+          parent.self_and_ancestors.select(:id)
         elsif project_context?(parent)
-          parent.group&.self_and_ancestors_ids
+          parent.group&.self_and_ancestors&.select(:id)
         end
       end
 

spec/models/milestone_spec.rb

@@ -286,8 +286,8 @@
     end
 
     context 'relations as params' do
-      let(:projects) { Project.where(id: project.id) }
-      let(:groups) { Group.where(id: group.id) }
+      let(:projects) { Project.where(id: project.id).select(:id) }
+      let(:groups) { Group.where(id: group.id).select(:id) }
 
       it_behaves_like 'filters by projects and groups'
     end