1 files changed, 25 insertions, 4 deletions
diff --git a/lib/api/milestone_responses.rb b/lib/api/milestone_responses.rb
index 8ff885983bc..ec108ea8c83 100644
--- a/lib/api/milestone_responses.rb
+++ b/lib/api/milestone_responses.rb
@@ -31,12 +31,14 @@ module API
         end
 
         def list_milestones_for(parent)
-          milestones = parent.milestones.order_id_desc
-          milestones = Milestone.filter_by_state(milestones, params[:state])
-          milestones = filter_by_iid(milestones, params[:iids]) if params[:iids].present?
-          milestones = filter_by_title(milestones, params[:title]) if params[:title]
+          finder_params = params.merge(milestones_finder_params(parent))
+          milestones = MilestonesFinder.new(finder_params).execute
           milestones = filter_by_search(milestones, params[:search]) if params[:search]
 
+          if params[:iids].present? && !params[:include_parent_milestones]
+            milestones = filter_by_iid(milestones, params[:iids])
+          end
+
           present paginate(milestones), with: Entities::Milestone
         end
 
@@ -96,6 +98,25 @@ module API
             [MergeRequestsFinder, Entities::MergeRequestBasic]
           end
         end
+
+        def milestones_finder_params(parent)
+          if parent.is_a?(Group)
+            { group_ids: parent.id }
+          else
+            {
+              project_ids: parent.id,
+              group_ids: parent_group_ids(parent)
+            }
+          end
+        end
+
+        def parent_group_ids(parent)
+          return unless params[:include_parent_milestones].present?
+
+          parent.group.self_and_ancestors
+                      .public_or_visible_to_user(current_user)
+                      .select(:id)
+        end
       end
     end
   end