1：在实际开发中，我们会经常使用到无限递归的情况，如菜单，父子级等的情况

2：Code

 1 using System;
 2 using System.Collections.Generic;
 3 using ConsoleApp1.Models;
 4 using System.Linq;
 5 using Newtonsoft.Json;
 6 namespace ConsoleApp1
 7 {
 8     class Program
 9     {
10         static void Main(string[] args)
11         {
12             var allData = GetListData();
13             var parentNode = allData.Where(p => p.PParentId == 0).ToList();
14             List<PersonModel> tree = new List<PersonModel>();
15             foreach (var item in parentNode)
16             {
17                 PersonModel p1 = new PersonModel { Children = new List<PersonModel> { } };
18                 int _id = item.ID;
19                 p1.ID = _id;
20                 p1.Pname = item.Pname;
21                 p1.Age = item.Age;
22                 p1.PParentId = item.PParentId;
23                 GetNewNodes(allData, p1);
24                 tree.Add(p1);
25             }
26             string jsonTree = JsonConvert.SerializeObject(tree, Formatting.Indented);
27             Console.WriteLine(jsonTree);
28             Console.ReadKey();
29         }
30 
31         static void GetNewNodes(List<PersonModel> all, PersonModel curItem)
32         {
33             var subItems = all.Where(c => c.PParentId == curItem.ID).ToList();
34             curItem.Children = new List<PersonModel>();
35             curItem.Children.AddRange(subItems);
36             foreach (var subItem in subItems)
37             {
38                 GetNewNodes(all, subItem);
39             }
40         }
41         static List<PersonModel> GetListData()
42         {
43             return new List<PersonModel> {
44                     new PersonModel{ID=1001,Age=68,Pname="QQ1",PParentId=0 },
45                     new PersonModel{ID=1002,Age=78,Pname="ww",PParentId=0 },
46                     new PersonModel{ID=1003,Age=67,Pname="dd",PParentId=0 },
47                     new PersonModel{ID=1004,Age=88,Pname="ff",PParentId=0 },
48 
49                     new PersonModel{ID=1005,Age=18,Pname="gg",PParentId=1001},
50                     new PersonModel{ID=1006,Age=16,Pname="cc",PParentId=1003},
51                     new PersonModel{ID=1007,Age=17,Pname="aa",PParentId=1006},
52                     new PersonModel{ID=1008,Age=19,Pname="tt",PParentId=1007},
53                     new PersonModel{ID=1009,Age=20,Pname="ii",PParentId=1004},
54                      new PersonModel{ID=1010,Age=22,Pname="ggf",PParentId=1003}
55             };
56         }
57     }
58 }

3:测试ok截图