issuable#labels_array explicitly load the labels

This will be useful when you want to ask for the 
number of items and later iterate over them, without 
needing to ask if the association is load or not.

So you avoid extra database queries

4 files changed, 24 insertions, 5 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 6a87e091940..84e755e4ead 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -30,6 +30,7 @@ v 8.9.0 (unreleased)
   - Add Application Setting to configure Container Registry token expire delay (default 5min)
   - Cache assigned issue and merge request counts in sidebar nav
   - Cache project build count in sidebar nav
+  - Reduce number of queries needed to render issue labels in the sidebar
 
 v 8.8.3
   - Fix incorrect links on pipeline page when merge request created from fork
diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index 50f5b749e38..e86d5236abb 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -213,6 +213,10 @@ module Issuable
     hook_data
   end
 
+  def labels_array
+    labels.to_a
+  end
+
   def label_names
     labels.order('title ASC').pluck(:title)
   end
diff --git a/app/views/shared/issuable/_sidebar.html.haml b/app/views/shared/issuable/_sidebar.html.haml
index c1eec450193..d6552ae7f18 100644
--- a/app/views/shared/issuable/_sidebar.html.haml
+++ b/app/views/shared/issuable/_sidebar.html.haml
@@ -114,20 +114,20 @@
           .sidebar-collapsed-icon
             = icon('tags')
             %span
-              = issuable.labels.count
+              = issuable.labels_array.size
           .title.hide-collapsed
             Labels
             = icon('spinner spin', class: 'block-loading')
             - if can_edit_issuable
               = link_to 'Edit', '#', class: 'edit-link pull-right'
-          .value.bold.issuable-show-labels.hide-collapsed{ class: ("has-labels" if issuable.labels.any?) }
-            - if issuable.labels.any?
-              - issuable.labels.each do |label|
+          .value.bold.issuable-show-labels.hide-collapsed{ class: ("has-labels" if issuable.labels_array.any?) }
+            - if issuable.labels_array.any?
+              - issuable.labels_array.each do |label|
                 = link_to_label(label, type: issuable.to_ability_name)
             - else
               .light None
           .selectbox.hide-collapsed
-            - issuable.labels.each do |label|
+            - issuable.labels_array.each do |label|
               = hidden_field_tag "#{issuable.to_ability_name}[label_names][]", label.id, id: nil
             .dropdown
               %button.dropdown-menu-toggle.js-label-select.js-multiselect{type: "button", data: {toggle: "dropdown", field_name: "#{issuable.to_ability_name}[label_names][]", ability_name: issuable.to_ability_name, show_no: "true", show_any: "true", project_id: (@project.id if @project), issue_update: issuable_json_path(issuable), labels: (namespace_project_labels_path(@project.namespace, @project, :json) if @project)}}
diff --git a/spec/models/concerns/issuable_spec.rb b/spec/models/concerns/issuable_spec.rb
index fb20578d8d3..e9f827e9f50 100644
--- a/spec/models/concerns/issuable_spec.rb
+++ b/spec/models/concerns/issuable_spec.rb
@@ -227,6 +227,20 @@ describe Issue, "Issuable" do
     end
   end
 
+  describe '#labels_array' do
+    let(:project) { create(:project) }
+    let(:bug) { create(:label, project: project, title: 'bug') }
+    let(:issue) { create(:issue, project: project) }
+
+    before(:each) do
+      issue.labels << bug
+    end
+
+    it 'loads the association and returns it as an array' do
+      expect(issue.reload.labels_array).to eq([bug])
+    end
+  end
+
   describe "votes" do
     let(:project) { issue.project }