如何获取嵌套级别排序的嵌套行？

Question

我下面的表格与属性：Id，ParentId，Name等 表包含嵌套层次为：Objects包含Elements包含Components）。

Id | Parent | Name 
--------------------------------------- 
1 | NULL | Name (this is object 1)  
2 | 1  | Name (this is element 1) 
3 | 2  | Name (this is component 1) 
4 | 2  | Name (this is component 2) 
5 | 2  | Name (this is component 3) 
6 | 1  | Name (this is element 2) 
7 | 6  | Name (this is component 4) 
8 | 1  | Name (this is element 3) 
9 | NULL | Name (this is object 2) 
10 | 9  | Name (this is element 4) 
11 | 10  | Name (this is component 5) 
12 | 10  | Name (this is component 6) 

我需要一个LINQ查询处理这一结果如出现表。我不想用nested for loops来获取对象，然后为每个对象获取其元素，然后为每个元素获取其组件 - 同样是在表上递归，我不想这样做。

Answer 1

不适用于一个linq语句。使用递归方法：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Data; 


namespace ConsoleApplication7 
{ 
    class Program 
    { 
     static void Main(string[] args) 
     { 
      DataTable dt = new DataTable(); 
      dt.Columns.Add("Id", typeof(int)); 
      dt.Columns.Add("Parent", typeof(int)); 
      dt.Columns.Add("Name", typeof(string)); 

      dt.Rows.Add(new object[] { 1, null, "Name (this is object 1)" }); 
      dt.Rows.Add(new object[] { 2, 1, "Name (this is element 1)" }); 
      dt.Rows.Add(new object[] { 3, 2, "Name (this is component 1)" }); 
      dt.Rows.Add(new object[] { 4, 2, "Name (this is component 2)" }); 
      dt.Rows.Add(new object[] { 5, 2, "Name (this is component 3)" }); 
      dt.Rows.Add(new object[] { 6, 1, "Name (this is element 2)" }); 
      dt.Rows.Add(new object[] { 7, 6, "Name (this is component 4)"}); 
      dt.Rows.Add(new object[] { 8, 1, "Name (this is element 3)" }); 
      dt.Rows.Add(new object[] { 9, null, "Name (this is object 2)" }); 
      dt.Rows.Add(new object[] { 10, 9, "Name (this is element 4)" }); 
      dt.Rows.Add(new object[] { 11, 10, "Name (this is component 5)" }); 
      dt.Rows.Add(new object[] { 12, 10, "Name (this is component 6)" }); 

      Node.RecursiveFill(dt, null, Node.root); 

     } 

    } 
    public class Node 
    { 
     public static Node root = new Node(); 

     public List<Node> children { get; set; } 
     public int id { get; set; } 
     public string name { get; set; } 

     public static void RecursiveFill(DataTable dt, int? parentId, Node parentNode) 
     { 
      foreach (DataRow row in dt.AsEnumerable().Where(x => x.Field<int?>("Parent") == parentId)) 
      { 
       Node newChild = new Node(); 
       if (parentNode.children == null) parentNode.children = new List<Node>(); 
       parentNode.children.Add(newChild); 
       newChild.id = row.Field<int>("Id"); 
       newChild.name = row.Field<string>("Name"); 
       RecursiveFill(dt, newChild.id, newChild); 
      } 
     } 
    } 

}