1 files changed, 34 insertions, 0 deletions
diff --git a/app/models/preloaders/labels_preloader.rb b/app/models/preloaders/labels_preloader.rb
new file mode 100644
index 00000000000..427f2869aac
--- /dev/null
+++ b/app/models/preloaders/labels_preloader.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module Preloaders
+  # This class preloads the `project`, `group`, and subscription associations for the given
+  # labels, user, and project (if provided). A Label can be of type ProjectLabel or GroupLabel
+  # and the preloader supports both.
+  #
+  # Usage:
+  #   labels = Label.where(...)
+  #   Preloaders::LabelsPreloader.new(labels, current_user, @project).preload_all
+  #   labels.first.project # won't fire any query
+  class LabelsPreloader
+    attr_reader :labels, :user, :project
+
+    def initialize(labels, user, project = nil)
+      @labels = labels
+      @user = user
+      @project = project
+    end
+
+    def preload_all
+      preloader = ActiveRecord::Associations::Preloader.new
+
+      preloader.preload(labels.select {|l| l.is_a? ProjectLabel }, { project: [:project_feature, namespace: :route] })
+      preloader.preload(labels.select {|l| l.is_a? GroupLabel }, { group: :route })
+      labels.each do |label|
+        label.lazy_subscription(user)
+        label.lazy_subscription(user, project) if project.present?
+      end
+    end
+  end
+end
+
+Preloaders::LabelsPreloader.prepend_if_ee('EE::Preloaders::LabelsPreloader')