C#-CheckboxList选择清除链接按钮单击(尽管回发检查)

清除复选框属性之前如何检索它们？

单击“开始！”后,我想计算复选框的数量.相反,单击后,将清除这些框(甚至是默认为选中的框),并且计数为零.

我是否需要另一种保护值免受回发的方法？

 
→

* .aspx

<%@ Page Language="C#" Inherits="LunaIntraDB.sandbox" MasterPageFile="~/SiteMaster.master" %>
<%@ MasterType VirtualPath="~/SiteMaster.master" %>
<asp:Content ContentPlaceHolderID="HeadContent" ID="HeadContentContent" runat="server">
</asp:Content>
<asp:Content ContentPlaceHolderID="MainContent" ID="MainContentContent" runat="server">

<asp:CheckBoxList ID="aCheckBoxList" runat="server" >
  <asp:ListItem Value="DontCheck" runat="server">1</asp:ListItem>
  <asp:ListItem Value="blah" Selected="True" runat="server">2</asp:ListItem>
</asp:CheckBoxList>

 <asp:LinkButton ID="goButton" runat="server" Text="Go!" onclick="Clicked" />

</asp:Content>

* .cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using MySql.Data.MySqlClient;
using System.Data;
using System.Collections;

namespace LunaIntraDB
{

    public partial class sandbox : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack) {
                debugPrint("Load,beforeAdd");
                aCheckBoxList.Items.Add("Added 1");
                aCheckBoxList.Items.Add("Added 2");
                aCheckBoxList.Items.Add("Added 3");
                aCheckBoxList.Items[4].Selected = true;
                debugPrint("Load,addedItems");

            } else {
                debugPrint("PostBack");
            }
        }

        protected void Clicked(object sender, EventArgs e)
        {
            debugPrint("Button push");
        }

        /* Print Selected index and a count of selected checkboxes */
        protected void debugPrint(String where) {
            String count = aCheckBoxList.Items.Cast<ListItem>().Where(n => n.Selected).ToList().Count.ToString();
            System.Diagnostics.Debug.WriteLine(where +": "+ aCheckBoxList.SelectedIndex.ToString() + " =>" + count + "/"+ aCheckBoxList.Items.Count.ToString()  );
        }
    }
}

控制台输出

[0:] Load,beforeAdd: 1 =>1/2

[0:] Load,addedItems: 1 =>2/5

// check a bunch and click “Go!”

[0:] PostBack: -1 =>0/5

[0:] Button push: -1 =>0/5

单声道版本

Mono JIT compiler version 3.2.3 (tarball Sun Sep 22 20:38:43 UTC 2013) Copyright (C) 2002-2012 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
        TLS:           __thread
        SIGSEGV:       altstack
        Notifications: epoll
        Architecture:  amd64
        Disabled:      none
        Misc:          softdebug 
        LLVM:          supported, not enabled.
        GC:            sgen

解决方法:

尽管@Will的答案是正确的,但这并不是整个问题的结论.

例如,当CheckBoxList位于Repeater控件内部时,ClientID具有不同的格式以指示CheckBoxList在Repeater中的位置.

可以肯定地说,我们并不是真的希望每次使用CheckBoxList都处理此问题,因此我创建了一个自定义控件,该控件扩展了CheckBoxList.OnLoad事件以解决上述问题.

namespace YOURNAMESPACE.Controls
{
    using System.Text.RegularExpressions;
    using System;
    using System.Web;
    using WebControls = System.Web.UI.WebControls;

    public class CheckBoxList : WebControls.CheckBoxList
    {
        protected override void onl oad(EventArgs e)
        {
            base.OnLoad(e);

            if (HttpContext.Current.Request.HttpMethod == "POST" && Type.GetType("Mono.Runtime") != null) {

                string cblFormID = Regex.Replace(ClientID, @"_\d+$", String.Empty).Replace("_", "$");

                int i = 0;
                foreach (WebControls.ListItem item in Items)
                    item.Selected = HttpContext.Current.Request.Form[cblFormID + "$" + i++] == item.Value;
            }
        }
    }
}

标签：checkboxlist,mono,asp-net,c
来源： https://codeday.me/bug/20191122/2058627.html