Add ability to filter labels by title or description

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/controllers/projects/labels_controller.rb

@@ -160,7 +160,10 @@ class Projects::LabelsController < Projects::ApplicationController
 
   def find_labels
     @available_labels ||=
-      LabelsFinder.new(current_user, project_id: @project.id, include_ancestor_groups: params[:include_ancestor_groups]).execute
+      LabelsFinder.new(current_user,
+                       project_id: @project.id,
+                       include_ancestor_groups: params[:include_ancestor_groups],
+                       search: params[:search]).execute
   end
 
   def authorize_admin_labels!

app/finders/labels_finder.rb

@@ -14,6 +14,7 @@ class LabelsFinder < UnionFinder
     @skip_authorization = skip_authorization
     items = find_union(label_ids, Label) || Label.none
     items = with_title(items)
+    items = by_search(items)
     sort(items)
   end
 
@@ -63,6 +64,12 @@ class LabelsFinder < UnionFinder
     items.where(title: title)
   end
 
+  def by_search(labels)
+    return labels unless params[:search].present?
+
+    labels.search(params[:search])
+  end
+
   # Gets redacted array of group ids
   # which can include the ancestors and descendants of the requested group.
   def group_ids_for(group)

app/models/label.rb

@@ -2,6 +2,7 @@ class Label < ActiveRecord::Base
   include CacheMarkdownField
   include Referable
   include Subscribable
+  include Gitlab::SQL::Pattern
 
   # Represents a "No Label" state used for filtering Issues and Merge
   # Requests that have no label assigned.
@@ -103,6 +104,17 @@ class Label < ActiveRecord::Base
     nil
   end
 
+  # Searches for labels with a matching title or description.
+  #
+  # This method uses ILIKE on PostgreSQL and LIKE on MySQL.
+  #
+  # query - The search query as a String.
+  #
+  # Returns an ActiveRecord::Relation.
+  def self.search(query)
+    fuzzy_search(query, [:title, :description])
+  end
+
   def open_issues_count(user = nil)
     issues_count(user, state: 'opened')
   end