检查是否有对ListBox控件选择

在前网页前端处，我们放置ListBox控件，在数据提交前，检查用户是否有对此控件进行选择？ Insus.NET的方法是使用Javascript与CustomValidator自定义验证控件来检查。

可以看到最终结果：

 

你也想参此例子，可以参考下面数据与准备方法，写一个对象，它将用来产生十个天干。

HeavenlyStem.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;



/// <summary>

/// Summary description for HeavenlyStem

/// </summary>

public class HeavenlyStem

{

    private int _ID;

    private string _Name;



    public int ID

    {

        get { return _ID; }

        set { _ID = value; }

    }



    public string Name

    {

        get { return _Name; }

        set { _Name = value; }

    }



    public HeavenlyStem()

    {

        //

        // TODO: Add constructor logic here

        //

    }



     public HeavenlyStem(int id, string name)

        {

            this.ID = id;

            this._Name = name;

        }

}

产生与用泛型来存储它们：

View Code

 private List<HeavenlyStem> GetHeavenStem()

    {

        List<HeavenlyStem> ListHS = new List<HeavenlyStem>();

        HeavenlyStem hs = new HeavenlyStem();

        hs.ID = 1;

        hs.Name = "甲";

        ListHS.Add(hs);



        hs = new HeavenlyStem();

        hs.ID = 2;

        hs.Name = "乙";

        ListHS.Add(hs);



        hs = new HeavenlyStem();

        hs.ID = 3;

        hs.Name = "丙";

        ListHS.Add(hs);



        hs = new HeavenlyStem();

        hs.ID = 4;

        hs.Name = "丁";

        ListHS.Add(hs);



        hs = new HeavenlyStem();

        hs.ID = 5;

        hs.Name = "戊";

        ListHS.Add(hs);



        hs = new HeavenlyStem();

        hs.ID = 6;

        hs.Name = "己";

        ListHS.Add(hs);



        hs = new HeavenlyStem();

        hs.ID = 7;

        hs.Name = "庚";

        ListHS.Add(hs);



        hs = new HeavenlyStem();

        hs.ID = 8;

        hs.Name = "辛";

        ListHS.Add(hs);



        hs = new HeavenlyStem();

        hs.ID = 9;

        hs.Name = "壬";

        ListHS.Add(hs);



        hs = new HeavenlyStem();

        hs.ID = 10;

        hs.Name = "癸";

        ListHS.Add(hs);



        return ListHS;

    }

Html标记：

View Code

<asp:ListBox ID="ListBoxHeavenlyStem" runat="server" Width="60" Height="160" SelectionMode="Multiple"></asp:ListBox>

            <asp:CustomValidator ID="CustomValidator1" runat="server" Display="None" ErrorMessage="必须选择选项" ClientValidationFunction="ValidateListBox"></asp:CustomValidator>



            <asp:ValidationSummary ID="ValidationSummary1" runat="server" EnableClientScript="true"

                ShowMessageBox="true" ShowSummary="false" />

            <asp:Button ID="Button1" runat="server" Text="Submit" />

接下来，你需要在.aspx.cs为ListBox控件绑定数据，数据源即是刚才产生的List<HeavenlyStem>：

View Code

using System.Collections.Generic;

using System.Data;

using System.Data.OleDb;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using Insus.NET;



public partial class _Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

        if (!IsPostBack)

            Data_Binding();

    }



    private void Data_Binding()

    {

        this.ListBoxHeavenlyStem.DataSource = GetHeavenStem();

        this.ListBoxHeavenlyStem.DataTextField = "Name";

        this.ListBoxHeavenlyStem.DataValueField = "ID";

        this.ListBoxHeavenlyStem.DataBind();

    }   

}

最后是写Javascript脚本：

View Code

function ValidateListBox(sender, args) {

            var lb = document.getElementById("<%=ListBoxHeavenlyStem.ClientID%>")

            var options = lb.options;



            args.IsValid = false;



            for (var i = 0; i < options.length; i++) {

                if (options[i].selected == true) {

                    args.IsValid = true;

                    return;

                }

            }

        }