Question

我在数据库中有一个菜单列表，如下所示。如何在C＃中为下面显示的数据创建一个类似于结构的对象树。

Id  MenuLabel ParentMenuId
1   Home           0         // Main Menu
2   MyAccounts     0         // Main Menu
3   MyProfile      2         // Sub Menu, parent menu is MyAccounts
4   Trade          0         // Main Menu
5   Stock          4         // Sub Menu, parent menu is Trade
6   Bonds          4         // Sub Menu, parent menu is Trade

理想情况下，我需要C＃中的对象结构。是否有任何最佳实践或模式？

Home
MyAccounts
----MyProfile
Trade
----Stock
----Bonds

Answer 1

使用字典。 parentDict创建您正在寻找的结构。

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("Id", typeof(int));
            dt.Columns.Add("MenuLabel", typeof(string));
            dt.Columns.Add("ParentMenuId", typeof(int));

            dt.Rows.Add(new object[] {1, "Home",0});         // Main Menu
            dt.Rows.Add(new object[] {2, "MyAccounts",0});   // Main Menu
            dt.Rows.Add(new object[] {3, "MyProfile",2});    // Sub Menu, parent menu is MyAccounts
            dt.Rows.Add(new object[] {4, "Trade", 0});       // Main Menu
            dt.Rows.Add(new object[] {5, "Stock", 4});       // Sub Menu, parent menu is Trade
            dt.Rows.Add(new object[] {6, "Bonds", 4 });     // Sub Menu, parent menu is Trade

            Dictionary<int, List<DataRow>> parentDict = dt.AsEnumerable()
                .GroupBy(x => x.Field<int>("ParentMenuId"), y => y)
                .ToDictionary(x => x.Key, y => y.ToList());


            Dictionary<int, DataRow> dict = dt.AsEnumerable()
                .GroupBy(x => x.Field<int>("Id"), y => y)
                .ToDictionary(x => x.Key, y => y.FirstOrDefault());

            int menu = 3;
            List<DataRow> parents = new List<DataRow>();
            for (int row = menu; (int)dict[row]["ParentMenuId"] != 0; row = (int)dict[row]["ParentMenuId"])
            {
                parents.Add(dict[(int)dict[row]["ParentMenuId"]]);
            }


        }

    }

}

从对象列表中递归创建对象树结构

1 个答案: