LASAPlatform/OpenAuth.App/BaseApp/Base/Tree/TreeExtensions.cs

using OpenAuth.Repository.Core;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace OpenAuth.App.Base.Tree
{
    public static class TreeExtensions
    {
        public static IEnumerable<TreeItemLong> BuildTree(this List<TreeItemLong> nodes, long? parentId = null)
        {
            var rootNodes = nodes
                .Where(n => n.ParentId == parentId || (parentId == null && (n.ParentId == null || !nodes.Any(child => child.Id == n.ParentId))));

            foreach (var rootNode in rootNodes)
            {
                yield return new TreeItemLong
                {
                    Id = rootNode.Id,
                    Name = rootNode.Name,
                    ParentId = rootNode.ParentId,
                    Level = rootNode.Level,
                    Children = nodes.BuildTree(rootNode.Id).ToList()
                };
            }
        }




        public static List<TreeItemLong> BuildTree1(this List<TreeItemLong> nodes, long? parentId = null)
        {
            var result = new List<TreeItemLong>();

            foreach (var node in nodes.Where(n => n.ParentId == parentId))
            {
                var newNode = new TreeItemLong
                {
                    Id = node.Id,
                    Name = node.Name,
                    ParentId = node.ParentId,
                    Children = nodes.BuildTree1(node.Id)
                };

                result.Add(newNode);
            }

            return result;
        }
    }
}