Loads move issue dropdown async

Closes #16563

app/assets/javascripts/issuable_form.js.coffee

@@ -19,6 +19,7 @@ class @IssuableForm
     @form.on "click", ".btn-cancel", @resetAutosave
 
     @initWip()
+    @initMoveDropdown()
 
   initAutosave: ->
     new Autosave @titleField, [
@@ -80,3 +81,19 @@ class @IssuableForm
 
   addWip: ->
     @titleField.val "WIP: #{@titleField.val()}"
+
+  initMoveDropdown: ->
+    $moveDropdown = $('.js-move-dropdown')
+
+    if $moveDropdown.length
+      $('.js-move-dropdown').select2
+        ajax:
+          url: $moveDropdown.data('projects-url')
+          results: (data) ->
+            return {
+              results: data
+            }
+        formatResult: (project) ->
+          project.name_with_namespace
+        formatSelection: (project) ->
+          project.name_with_namespace

app/controllers/autocomplete_controller.rb

@@ -31,6 +31,21 @@ class AutocompleteController < ApplicationController
     render json: @user, only: [:name, :username, :id], methods: [:avatar_url]
   end
 
+  def projects
+    project = Project.find_by_id(params[:project_id])
+
+    projects = current_user.authorized_projects
+    projects = projects.select do |project|
+      current_user.can?(:admin_issue, project)
+    end
+
+    no_project = OpenStruct.new(id: 0, name_with_namespace: 'No project')
+    projects.unshift(no_project.marshal_dump)
+    projects.delete(project)
+
+    render json: projects.to_json(only: [:id, :name_with_namespace], methods: :name_with_namespace)
+  end
+
   private
 
   def find_users

app/views/shared/issuable/_form.html.haml

@@ -90,9 +90,7 @@
     = label_tag :move_to_project_id, 'Move', class: 'control-label'
     .col-sm-10
       .issuable-form-select-holder
-        - projects = project_options(issuable, current_user, ability: :admin_issue)
-        = select_tag(:move_to_project_id, projects, include_blank: true,
-                     class: 'select2', data: { placeholder: 'Select project' })
+        = hidden_field_tag :move_to_project_id, nil, class: 'js-move-dropdown', data: { placeholder: 'Select project', projects_url: autocomplete_projects_path(project_id: '1') }
        
       %span{ data: { toggle: 'tooltip', placement: 'auto top' }, style: 'cursor: default',
       title: 'Moving an issue will copy the discussion to a different project and close it here. All participants will be notified of the new location.' }

config/routes.rb

@@ -56,6 +56,7 @@ Rails.application.routes.draw do
   # Autocomplete
   get '/autocomplete/users' => 'autocomplete#users'
   get '/autocomplete/users/:id' => 'autocomplete#user'
+  get '/autocomplete/projects' => 'autocomplete#projects'
 
   # Emojis
   resources :emojis, only: :index