如果第一个组合框值是在C＃中安排的，则启用第二个组合框

Question

Greetings for the Day!!

I am a newbie to DOT NET. Developing a tool, building UI.

I am stuck in generating combo box values on selection of other combo box.

Question is : There are 2 Combo box : DropDownList1 and DropDownList2 DropDownList1 values: 0-All 1-Not Scheduled 2-Rejected 3-Selected DropDownList2 values: 0-Select ALL 1-Poor Communication 3-Failed in test 4-Poor Typing skill

Values are populating in the combobox.

// for DropDownList1

            SqlConnection con = new SqlConnection("Data Source=.;Initial                   Catalog=Test_DB;User ID=sa");
        con.Open();

        //Interview Status
        string Sql = "select Id,Status from dbo.InterviewStatus";

        SqlCommand cmd = new SqlCommand(Sql, con);
        cmd.CommandType = CommandType.Text;
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        if (ds.Tables[0].Rows.Count > 0)
        {
           DropDownList1.DataSource = ds.Tables[0];
           DropDownList1.DataTextField = "Status";
           DropDownList1.DataValueField = "Id";
           DropDownList1.DataBind();
           DropDownList1.Items.Insert(0, new ListItem("All", "0"));
        }

Now, DropDownList2 should be enabled only when DropDownList1 is Rejected. for other DropDownList1 values, DropDownList2 should be disabled.

Kindly help me in resolving this.

Thanks in advance :)

Answer 1

If I understood you correctly, you can use the SelectedIndexChanged event and check the values in your cboStatus

private void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (DropDownList1.SelectedItem.ToString() == "2")
    {
        DropDownList2.Enabled = true;
    }
}

EDIT:

Since the index seems to coincide with your Status values you actually need only the index, unless it is an important information for the user. To populate you ComboBox just get the values from you database as a List and use the AddRange method

DropDownList1.Items.AddRange(listOfValues.ToArray());

Answer 2

You can do the cascading style drop down lists by following the below given approach, also you can populate the cboComments DropDownList during the intialization process itself as the data is small and as it is an aspx control you will typically do it in the Page_Load event you can see this thread for more information.

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="CascadingDDL._Default" %>

<asp:Content ID="BodyContent" ContentPlaceHolderID="MainContent" runat="server">

    <div class="jumbotron">
        <h1>Cascading Drop Down List</h1>
    </div>

    <div class="row">
        <div class="col-md-12">
            <asp:DropDownList ID="cboStatus" runat="server" AutoPostBack="true" OnSelectedIndexChanged="cboStatus_SelectedIndexChanged">
                <asp:ListItem Value="0" Text="All"></asp:ListItem>
                <asp:ListItem Value="1" Text="Not Scheduled"></asp:ListItem>
                <asp:ListItem Value="2" Text="Rejected"></asp:ListItem>
                <asp:ListItem Value="3" Text="Selected"></asp:ListItem>
            </asp:DropDownList>

            <asp:DropDownList ID="cboComments" runat="server">
                <asp:ListItem Value="0" Text="Select All"></asp:ListItem>
                <asp:ListItem Value="1" Text="Poor Communication"></asp:ListItem>
                <asp:ListItem Value="3" Text="Failed in Test"></asp:ListItem>
                <asp:ListItem Value="4" Text="Poor Typing skill"></asp:ListItem>
            </asp:DropDownList>
        </div>
    </div>

</asp:Content>

The Code-Behind

namespace CascadingDDL
{
    using System;
    using System.Web.UI;

    public partial class _Default : Page
    {
        public const int StatusRejected = 2;

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!this.IsPostBack)
            {
                this.cboComments.Enabled = false;
            }
        }

        protected void cboStatus_SelectedIndexChanged(object sender, EventArgs e)
        {
            var status = int.Parse(this.cboStatus.SelectedValue);
            if (status == StatusRejected)
            {
                this.cboComments.Enabled = true;
            }
            else
            {
                this.cboComments.Enabled = false;
            }
        }
    }
}