Fixes #4095 - Trigger autocomplete when clicking the "Tags" field also without a search term.

.overcommit.yml

@@ -15,10 +15,15 @@ PreCommit:
     on_warn: fail
   CoffeeLint:
     # .coffeelint/rules/* not supported in YAML, specify all rules separately.
-    flags: ['--reporter=csv', '--rules', './.coffeelint/rules/detect_translatable_string.coffee']
+    flags:
+      [
+        '--reporter=csv',
+        '--rules',
+        './.coffeelint/rules/detect_translatable_string.coffee',
+      ]
     enabled: true
     on_warn: fail
-    exclude: public/assets/chat/**/*
+    exclude: 'public/assets/chat/**/*'
   CustomScript:
     enabled: true
     description: 'Check if translation catalog is up-to-date'

app/assets/javascripts/app/controllers/widget/tag.coffee

@@ -57,7 +57,7 @@ class App.WidgetTag extends App.Controller
     source = "#{App.Config.get('api_path')}/tag_search"
     @$('.js-newTagInput').autocomplete(
       source: source
-      minLength: 1
+      minLength: 0
       response: (e, ui) =>
         return if !ui
         return if !ui.content

app/controllers/tags_controller.rb

@@ -6,7 +6,8 @@ class TagsController < ApplicationController
 
   # GET /api/v1/tag_search?term=abc
   def search
-    list = Tag::Item.where('name_downcase LIKE ?', "%#{params[:term].strip.downcase}%").order(name: :asc).limit(params[:limit] || 10)
+    list = get_tag_list(params[:term], params[:limit] || 10)
+
     results = []
     list.each do |item|
       result = {
@@ -95,4 +96,13 @@ class TagsController < ApplicationController
     render json: {}
   end
 
+  private
+
+  def get_tag_list(term, limit)
+    if term.blank?
+      return Tag::Item.left_outer_joins(:tags).group(:id).order('COUNT(tags.tag_item_id) DESC, name ASC').limit(limit)
+    end
+
+    Tag::Item.where('name_downcase LIKE ?', "%#{term.strip.downcase}%").order(name: :asc).limit(limit)
+  end
 end

app/models/tag/item.rb

@@ -4,6 +4,10 @@ class Tag::Item < ApplicationModel
   validates   :name, presence: true
   before_save :fill_namedowncase
 
+  has_many :tags, foreign_key: 'tag_item_id',
+                  inverse_of:  :tag_item,
+                  dependent:   :destroy
+
 =begin
 
 lookup by name and create tag item

spec/requests/tag_spec.rb

@@ -100,6 +100,18 @@ RSpec.describe Tag, type: :request do
         include_examples 'no tag found using', search_term: '1foobar'
         include_examples 'no tag found using', search_term: 'foobar2'
       end
+
+      context 'without search term' do
+        before do
+          create_list(:tag, 2, tag_item: tags.last)
+          create_list(:tag, 1, tag_item: tags.first)
+        end
+
+        it 'most used is on first place without search term' do
+          get '/api/v1/tag_search', params: { term: '' }
+          expect(json_response.first['value']).to eq(tags.last.name)
+        end
+      end
     end
   end
 end