如何通过嵌套级别获取嵌套行？

I have the following table with attributes: Id, ParentId, Name etc. The table contains a nesting level as: Objects contain Elements that contain Components).

我有下表的属性：Id，ParentId，Name等。该表包含嵌套级别：对象包含包含组件的元素。

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)

I need a single LINQ query that handles this result as in the presented table.

我需要一个LINQ查询来处理这个结果，就像在表格中一样。

I would not like to use nested for loops to get the objects, then for each object to get its elements, then for each element to get its components - the same is for recursion on the table and I do not want this.

我不想使用嵌套for循环来获取对象，然后为每个对象获取其元素，然后为每个元素获取其组件 - 同样是对表的递归而我不希望这样。

1 个解决方案

#1

Not appropriate for one linq statement. Use a recursive method :

不适合一个linq声明。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);
            }
        }
    }

}