DropDownList并在SelectedIndexChanged事件之后捕获值

本文介绍了DropDownList并在SelectedIndexChanged事件之后捕获值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

需要帮助请，我有两个DropDownLists(嵌套).我使用SelectedIndexChanged事件填充第二个DropDownList.

因此，问题在于我需要将DropDownLists的两个值都保存到数据库中，我可以轻松完成第一个DropDownList的操作，但是如何捕获第二个值(DropDownList2.SelectedItem.Value)?

这是我的代码的一部分..
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Need help please, i have two DropDownLists (nested). I use SelectedIndexChanged event to populate the second DropDownList.

So, the problem is that i need to save the both values of DropDownLists to a database, i can do easily for the first DropDownList , but how to capture the second value ( DropDownList2.SelectedItem.Value)?

this is a part of my code ..
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.
.

protected void Page_Load(object sender, EventArgs e)
{
	if (Page.IsPostBack == false)
	{
		// create SqlConnection object
		string ConnectionString = ConfigurationManager.ConnectionStrings["SqlConnectionString"].ConnectionString;
		SqlConnection myConnection = new SqlConnection(ConnectionString);
		// create SqlCommand object
		SqlCommand myCommand = new SqlCommand();
		myCommand.Connection = myConnection;
		try
		{
			myConnection.Open();
			myCommand.CommandText = "SELECT category_id, name FROM categories order by 2";
			// run query
			SqlDataReader myReader = myCommand.ExecuteReader();
			// set up the list
			DropDownList1.DataSource = myReader;
			DropDownList1.DataBind();
			// close the reader
			myReader.Close();
		}
		finally
		{
			// open the database connection
			myConnection.Close();
		}
	   
	}
}

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
	 // create SqlConnection object
	string ConnectionString = ConfigurationManager.ConnectionStrings["SqlConnectionString"].ConnectionString;
	SqlConnection myConnection = new SqlConnection(ConnectionString);
	// create SqlCommand object
	string CommandText = "SELECT sub_cat_id, name, category_id FROM sub_category WHERE category_id = " + DropDownList1.SelectedItem.Value;
	SqlCommand myCommand = new SqlCommand(CommandText, myConnection);

	try
	{
		// open the database connection
		myConnection.Open();
		// run query
		SqlDataReader myReader = myCommand.ExecuteReader();
		// setup the GridView
		DropDownList2.DataSource = myReader;
		DropDownList2.DataBind();
		// close the reader
		myReader.Close();
	}
	finally
	{
		// open the database connection
		myConnection.Close();

	}		
}

推荐答案

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="test.aspx.cs" Inherits="SampleWebApp.test" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList ID="dd1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="dd1_Changed"></asp:DropDownList>
        <br />
        <asp:DropDownList ID="dd2" runat="server" AutoPostBack="true" OnSelectedIndexChanged="dd2_Changed"></asp:DropDownList>
        <br />
        <asp:Label ID="lbl1" runat="server" Text=""></asp:Label>
    </div>
    </form>
</body>
</html>

C#代码隐藏:

C# code-behind:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace SampleWebApp
{
    public partial class test : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                dd1.DataSource = Data.GetSource(5);
                dd1.DataTextField = "Text";
                dd1.DataValueField = "Value";
                dd1.DataBind();
            }
        }

        protected void dd1_Changed(object sender, EventArgs e)
        {
            dd2.DataSource = Data.GetSource(int.Parse(dd1.SelectedValue));
            dd2.DataTextField = "Text";
            dd2.DataValueField = "Value";
            dd2.DataBind();
        }

        protected void dd2_Changed(object sender, EventArgs e)
        {
            lbl1.Text = dd1.SelectedValue.ToString() + " - " + dd2.SelectedValue.ToString();
        }
    }

    public class Data
    {
        public string Text { get; set; }
        public int Value { get; set; }

        public static List<Data> GetSource(int n)
        {
            List<Data> d = new List<Data>();
            Enumerable.Range(1, n).ToList().ForEach(delegate(int i)
            {
                Data dd = new Data { Text = i.ToString(), Value = i };
                d.Add(dd);
            });
            return d;
        }
    }
}

希望这可以帮助！让我(我们)知道您是否有任何疑问！

Hope this helps! Do let me (us) know if you have any questions!

protected void DropDownList2_PreRender(object sender, EventArgs e)
{ 
    Label1.Text = DropDownList2.SelectedValue.ToString(); 
}

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