Sort projects by last activity for project switcher in header

app/assets/javascripts/api.js.coffee

@@ -47,7 +47,7 @@
       callback(namespaces)
 
   # Return projects list. Filtered by query
-  projects: (query, callback) ->
+  projects: (query, order, callback) ->
     url = Api.buildUrl(Api.projects_path)
 
     $.ajax(
@@ -55,6 +55,7 @@
       data:
         private_token: gon.api_token
         search: query
+        order_by: order
         per_page: 20
       dataType: "json"
     ).done (projects) ->

app/assets/javascripts/project_select.js.coffee

@@ -3,6 +3,7 @@ class @ProjectSelect
     $('.ajax-project-select').each (i, select) ->
       @groupId = $(select).data('group-id')
       @includeGroups = $(select).data('include-groups')
+      @orderBy = $(select).data('order-by') || 'id'
 
       placeholder = "Search for project"
       placeholder += " or group" if @includeGroups
@@ -28,7 +29,7 @@ class @ProjectSelect
           if @groupId
             Api.groupProjects @groupId, query.term, projectsCallback
           else
-            Api.projects query.term, projectsCallback
+            Api.projects query.term, @orderBy, projectsCallback
 
         id: (project) ->
           project.web_url

app/helpers/projects_helper.rb

@@ -57,7 +57,10 @@ module ProjectsHelper
       link_output = simple_sanitize(project.name)
       link_output += content_tag :span, nil, { class: "fa fa-chevron-down dropdown-toggle-caret" } if current_user
 
-      link_output += project_select_tag :project_path, class: "project-item-select js-projects-dropdown", data: { include_groups: false } if current_user
+      if current_user
+        link_output += project_select_tag :project_path, class: "project-item-select js-projects-dropdown",
+          data: { include_groups: false, order_by: 'last_activity_at' }
+      end
 
       link_output
     end