Consider ids parameter

app/controllers/api/v2/planning_elements_controller.rb

@@ -39,7 +39,8 @@ module Api
 
       before_filter :find_project_by_project_id,
                     :authorize, :except => [:index]
-      before_filter :parse_changed_since, only: [:index]
+      before_filter :parse_changed_since,
+                    :parse_work_package_ids, only: [:index]
       before_filter :assign_planning_elements, :except => [:index, :update, :create]
 
       # Attention: find_all_projects_by_project_id needs to mimic all of the above
@@ -261,6 +262,8 @@ module Api
                                    .changed_since(@since)
                                    .includes(:status, :project, :type, :custom_values)
 
+        work_packages = work_packages.where(id: @wp_ids) if @wp_ids
+
         if params[:f]
           #we need a project to make project-specific custom fields work
           project = timeline_to_project(params[:timeline])
@@ -343,6 +346,10 @@ module Api
       def parse_changed_since
         @since = Time.at(Float(params[:changed_since] || 0).to_i) rescue render_400
       end
+
+      def parse_work_package_ids
+        @wp_ids = params[:ids] ? params[:ids].split(',') : nil
+      end
     end
   end
 end