Umbraco-CMS/src/Umbraco.Web.BackOffice/Trees/LanguageTreeController.cs

using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Umbraco.Cms.Core;
using Umbraco.Cms.Core.Events;
using Umbraco.Cms.Core.Services;
using Umbraco.Cms.Core.Trees;
using Umbraco.Cms.Web.Common.Attributes;
using Umbraco.Cms.Web.Common.Authorization;
using Constants = Umbraco.Cms.Core.Constants;

namespace Umbraco.Cms.Web.BackOffice.Trees
{
    [Authorize(Policy = AuthorizationPolicies.TreeAccessLanguages)]
    [Tree(Constants.Applications.Settings, Constants.Trees.Languages, SortOrder = 11, TreeGroup = Constants.Trees.Groups.Settings)]
    [PluginController(Constants.Web.Mvc.BackOfficeTreeArea)]
    [CoreTree]
    public class LanguageTreeController : TreeController
    {

        public LanguageTreeController(
            ILocalizedTextService textService,
            UmbracoApiControllerTypeCollection umbracoApiControllerTypeCollection,
            IEventAggregator eventAggregator)
            : base(textService, umbracoApiControllerTypeCollection, eventAggregator)
        {
        }
        protected override ActionResult<TreeNodeCollection> GetTreeNodes(string id, FormCollection queryStrings)
        {
            //We don't have any child nodes & only use the root node to load a custom UI
            return new TreeNodeCollection();
        }

        protected override ActionResult<MenuItemCollection> GetMenuForNode(string id, FormCollection queryStrings)
        {
            //We don't have any menu item options (such as create/delete/reload) & only use the root node to load a custom UI
            return null;
        }

        /// <summary>
        /// Helper method to create a root model for a tree
        /// </summary>
        /// <returns></returns>
        protected override ActionResult<TreeNode> CreateRootNode(FormCollection queryStrings)
        {
            var rootResult = base.CreateRootNode(queryStrings);
            if (!(rootResult.Result is null))
            {
                return rootResult;
            }
            var root = rootResult.Value;

            //this will load in a custom UI instead of the dashboard for the root node
            root.RoutePath = $"{Constants.Applications.Settings}/{Constants.Trees.Languages}/overview";
            root.Icon = Constants.Icons.Language;
            root.HasChildren = false;
            root.MenuUrl = null;

            return root;
        }


    }
}