EasyUI List<T>转tree数据格式

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;

namespace XHP
{
    /// <summary>
    /// 
    /// </summary>
    public class TreeDataHelper<T> where T:new()
    {
        public class TreeModelBase
        {
            public string id { get; set; }

            public string text { get; set; }

            /// <summary>
            /// closed
            /// </summary>
            public string state { get; set; }

            public List<TreeModelBase> children { get; set; }
        }

        /// <summary>
        /// 
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="list"></param>
        /// <param name="idFieldExp"></param>
        /// <param name="textFieldExp"></param>
        /// <param name="rootValue"></param>
        /// <param name="emptyRootName"></param>
        /// <param name="expendLevel">树默认展开级别-1全不展开，0展开所有，1只展开到1级</param>
        /// <returns></returns>
        public static List<TreeModelBase> GetTreeDataFromList<TProperty1, TProperty2, TProperty3>(List<T> list, Expression<Func<T, TProperty1>> idFieldExp,
            Expression<Func<T, TProperty2>> textFieldExp, Expression<Func<T, TProperty3>> pidFieldExp, string rootValue, string emptyRootName="==全部==",int expendLevel=1) 
        {
            Hashtable tb = new Hashtable();            

            var idProp = typeof(T).GetProperty(((MemberExpression)idFieldExp.Body).Member.Name);
            var textProp = typeof(T).GetProperty(((MemberExpression)textFieldExp.Body).Member.Name);
            var pidProp = typeof(T).GetProperty(((MemberExpression)pidFieldExp.Body).Member.Name);

            T parent = default(T);
            if(!string.IsNullOrWhiteSpace(rootValue))
            {
                parent = list.FirstOrDefault(x => idProp.GetValue(x)?.ToString() == rootValue);
            }

            TreeModelBase rlt = new TreeModelBase();
            if (parent == null)
            {
                rlt.id = rootValue??"";
                rlt.text = emptyRootName;
            }
            else
            {
                rlt.id = idProp.GetValue(parent).ToString();
                rlt.text = textProp.GetValue(parent).ToString();
            }
            rlt.state = expendLevel > -1 ? null : "closed";

            var currentLevel = 1;
            GetTreeDataFromList_SetChild(rlt, list, idProp, textProp, pidProp, expendLevel, currentLevel);

            return new List<TreeModelBase> { rlt } ;
        }
        

        private static void GetTreeDataFromList_SetChild(TreeModelBase parent,List<T> list,PropertyInfo idProp,PropertyInfo textProp, PropertyInfo pidProp, int expendLevel,int currentLevel)
        {
            var childs = list.Where(x => (pidProp.GetValue(x)?.ToString() ?? "") == (parent.id ?? "")  &&!string.IsNullOrWhiteSpace(idProp.GetValue(x)?.ToString()));
            if (childs.Count() == 0)
            {
                parent.state = null;
                return;
            }
            else
            {
                parent.children = new List<TreeModelBase>();
                foreach (var item in childs)
                {
                    var tempChild = new TreeModelBase();

                    tempChild.id = idProp.GetValue(item).ToString();
                    tempChild.text = textProp.GetValue(item).ToString();

                    if (expendLevel == 0)
                        tempChild.state = null;
                    else if (expendLevel == -1)
                        tempChild.state = "closed";
                    else
                    {
                        tempChild.state = currentLevel < expendLevel ? null : "closed";
                    }
                    currentLevel++;

                    GetTreeDataFromList_SetChild(tempChild, list, idProp, textProp, pidProp, expendLevel, currentLevel);

                    parent.children.Add(tempChild);
                }
            }
        }

    }
}