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Binding all college names to a college-dropdownlist based on data selected in another city-dropdownlist , both dropdownlists are placed inside the datalist

Rashmi S 2419 21-Nov-2014
Binding all college names to a college-dropdownlist based on city name selected in another city-dropdownlist , both dropdownlists are placed inside the datalist.
how should i create SelectedIndexChanged event for city-dropdownlist and to to bind college names to college-dropdownlist? please help me out...!

this is my code
<asp:DataList ID="DLpriority" runat="server" BackColor="White" 
                                BorderColor="#CC9966" BorderStyle="None" BorderWidth="1px" CellPadding="4" 
                                GridLines="Both">
                                <FooterStyle BackColor="#FFFFCC" ForeColor="#330099" />
                                <HeaderStyle BackColor="#990000" Font-Bold="True" ForeColor="#FFFFCC" />
                                <HeaderTemplate>
                                    <table style="width:100%;">
                                        <tr>
                                            <td style="width: 103px">
                                                Priority No.</td>
                                            <td style="width: 126px">
                                                City</td>
                                            <td align="center" style="width: 157px">
                                                College
                                            </td>
                                            <td align="center">
                                                Combination</td>
                                        </tr>
                                    </table>
                                </HeaderTemplate>
                                <ItemStyle BackColor="White" ForeColor="#330099" />
                                <ItemTemplate>
                                    <table border="3" style="width:100%;">
                                        <tr>
                                            <td>
                                                <asp:Label ID="lblProirityNo" runat="server" Text='<%# Eval("PriorityNo") %>' 
                                                    Width="100px"></asp:Label>
                                            </td>
                                            <td>
                                                <asp:DropDownList ID="DDLcity" runat="server" Width="200px" AutoPostBack="True" 
                                                    onselectedindexchanged="DDLcity_SelectedIndexChanged">
                                                </asp:DropDownList>
                                            </td>
                                            <td style="width: 202px">
                                                <asp:DropDownList ID="DDLcollege" runat="server" Width="200px">
                                                </asp:DropDownList>
                                            </td>
                                            <td>
                                                <asp:DropDownList ID="DDLcourse" runat="server" Width="150px">
                                                </asp:DropDownList>
                                            </td>
                                        </tr>
                                        <tr>
                                            <td>
                                                &nbsp;</td>
                                            <td>
                                                &nbsp;</td>
                                            <td style="width: 202px">
                                                &nbsp;</td>
                                            <td>
                                                &nbsp;</td>
                                        </tr>
                                        <tr>
                                            <td>
                                                &nbsp;</td>
                                            <td>
                                                &nbsp;</td>
                                            <td style="width: 202px">
                                                &nbsp;</td>
                                            <td>
                                                &nbsp;</td>
                                        </tr>
                                    </table>
                                </ItemTemplate>
                                <SelectedItemStyle BackColor="#FFCC66" Font-Bold="True" ForeColor="#663399" />
                            </asp:DataList>
.netdropdown 
Updated on 22-Nov-2014
Rashmi S

Rashmi S

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2 Answers

Rashmi S

Rashmi S

22-Nov-2014
Hi...
Thank you.. i tried your code is working fine...

This is me code which i tried... It may help others...!

source code :
<asp:Panel ID="Panel1" runat="server">
                <table style="width: 102%;">
                <tr>
                    <td>
                    <table style="width: 90%">
                    <tr bgcolor="#F4CF9D" 
                        style="font-weight: bold; font-style: normal; text-transform: capitalize; color: #990033; font-size: large">
                        <td align="left" style="height: 30px; width: 120px">
                            <strong>Register Number</strong></td>
                        <td align="left" style="height: 30px">
                            <asp:Label ID="lblRegNo" runat="server" ForeColor="Black"></asp:Label>
                        </td>
                        <td align="right" style="height: 30px">
                            <strong>Student Name&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </strong>
                        </td>
                        <td align="left" style="height: 30px">
                            <asp:Label ID="lblName" runat="server" ForeColor="Black"></asp:Label>
                        </td>
                    </tr>
                    <tr>
                        <td style="width: 120px">
                            &nbsp;</td>
                        <td>
                            &nbsp;</td>
                        <td>
                            &nbsp;</td>
                        <td>
                            &nbsp;</td>
                    </tr>
                    <tr>
                        <td style="width: 120px">
                            &nbsp;</td>
                        <td align="right">
                            Total Number of priorities&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </td>
                        <td align="left">
                            <asp:DropDownList ID="DDLcount" runat="server" Width="150px" 
                                AutoPostBack="True" onselectedindexchanged="DDLcount_SelectedIndexChanged">
                            </asp:DropDownList>
                        </td>
                        <td>
                            &nbsp;</td>
                    </tr>
                </table>
                    </td>
                </tr>
                <tr>
                    <td>
                        <hr />
                     </td>
                 </tr>
                    <tr>
                        <td align="left" style="height: 30px">
                            <asp:Panel ID="Panel2" runat="server">
                           
                            <asp:DataList ID="DLpriority" runat="server" BackColor="White" 
                                BorderColor="#CC9966" BorderStyle="None" BorderWidth="1px" CellPadding="4" 
                                GridLines="Both">
                                <FooterStyle BackColor="#FFFFCC" ForeColor="#330099" />
                                <HeaderStyle BackColor="#990000" Font-Bold="True" ForeColor="#FFFFCC" />
                                <HeaderTemplate>
                                    <table style="width:100%;">
                                        <tr>
                                            <td style="width: 103px">
                                                Priority No.</td>
                                            <td style="width: 126px">
                                                City</td>
                                            <td align="center" style="width: 157px">
                                                College
                                            </td>
                                            <td align="center">
                                                Combination</td>
                                        </tr>
                                    </table>
                                </HeaderTemplate>
                                <ItemStyle BackColor="White" ForeColor="#330099" />
                                <ItemTemplate>
                                    <table border="3" style="width:100%;">
                                        <tr>
                                            <td>
                                                <asp:Label ID="lblProirityNo" runat="server" Text='<%# Eval("PriorityNo") %>' 
                                                    Width="100px"></asp:Label>
                                            </td>
                                            <td>
                                                <asp:DropDownList ID="DDLcity" runat="server" Width="200px" AutoPostBack="True" 
                                                    onselectedindexchanged="DDLcity_SelectedIndexChanged">
                                                </asp:DropDownList>
                                            </td>
                                            <td style="width: 202px">
                                                <asp:DropDownList ID="DDLcollege" runat="server" Width="200px" 
                                                    AutoPostBack="True" onselectedindexchanged="DDLcollege_SelectedIndexChanged">
                                                </asp:DropDownList>
                                            </td>
                                            <td>
                                                <asp:DropDownList ID="DDLcourse" runat="server" Width="150px">
                                                </asp:DropDownList>
                                            </td>
                                        </tr>
                                    </table>
                                    &nbsp;
                                </ItemTemplate>
                                <SelectedItemStyle BackColor="#FFCC66" Font-Bold="True" ForeColor="#663399" />
                            </asp:DataList>
                            <br />
                            <br />
                            <asp:Button ID="btnSet" runat="server" BackColor="#D28215" Font-Bold="True" 
                                ForeColor="White" onclick="btnSet_Click" Text=" &gt;&gt; Set Priority" />
                             </asp:Panel>
                        </td>
                    </tr>
                    <tr>
                        <td>
                            &nbsp;</td>
                    </tr>
                </table>
                </asp:Panel>
 
Code behind(.aspx.cs ) :
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
namespace PUseatAllot.Student
{
    public partial class OptionEntry2  : System.Web.UI.Page
    {
        static int StudId;
        BL b = new BL();
        static int flg_editOption;
        static DataTable t_P_Details;
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!this.IsPostBack)
            {
                Panel1.Visible = false;
                Panel2.Visible = false;
                Panel3.Visible = false;
                StudId = int.Parse(Session["StudentID"].ToString());
                DataTable t_stud = b.Student_Get_StudId(StudId);
                if (t_stud.Rows.Count > 0)
                {
                    lblName.Text = t_stud.Rows[0]["StudentName"].ToString();
                    lblRegNo.Text = t_stud.Rows[0]["RegNo"].ToString();
                }
                //***********************************************************************************
                
                DataTable t_details = new DataTable();
                DataTable tab1 = b.test_Get_CCid(StudId);
                if (tab1.Rows.Count > 0)
                {
                    Panel3.Visible = true;
                    //-----------------------------------------------------------------
                    DataTable t_proirNo = new DataTable();
                    t_proirNo.Columns.Add("PriorityNo", typeof(int));
                    for (int i = 1; i <= tab1.Rows.Count; i++)
                    {
                        DataRow dt = t_proirNo.NewRow();
                        dt["PriorityNo"] = i.ToString();
                        t_proirNo.Rows.Add(dt);
                    }
                    DLpriority.DataSource = t_proirNo;
                    DLpriority.DataBind();
                    foreach (DataListItem item in DLpriority.Items)
                    {
                        DropDownList ddlCity = (DropDownList)item.FindControl("DDLcity");
                        ddlCity.DataSource = b.Cities_GetAll();
                        ddlCity.DataTextField = "CityName";
                        ddlCity.DataValueField = "CityId";
                        ddlCity.DataBind();
                        ddlCity.Items.Insert(0, "Select");
                        //DropDownList ddlClg = (DropDownList)item.FindControl("DDLcollege");
                        //ddlClg.Items.Insert(0, "Select");
                        //DropDownList ddlCou = (DropDownList)item.FindControl("DDLcourse");
                        //ddlCou.Items.Insert(0, "Select");
                    }
                    //--------------------------------------------------------------------
                    string ccid = null;
                    for (int i = 0; i < tab1.Rows.Count; i++)
                    {
                        ccid = ccid + "'" + tab1.Rows[i]["CCid"].ToString() + "'" + ",";
                    }
                    ccid = ccid.Substring(0, (ccid.Length - 1));
                    DataTable tab2 = b.test_GetClgCouId_CCid(ccid);
                    if (tab2.Rows.Count > 0)
                    {
                        
                        t_details.Columns.Add("PriorityNo", typeof(int));
                        t_details.Columns.Add("CollegeName", typeof(string));
                        t_details.Columns.Add("CourseName", typeof(string));
                        for (int j = 0; j < tab2.Rows.Count; j++)
                        {
                            int clgid = int.Parse(tab2.Rows[j]["CollegeId"].ToString());
                            int couid = int.Parse(tab2.Rows[j]["CourseId"].ToString());
                            DataRow dt = t_details.NewRow();
                            DataTable tab3 = b.test_GetClgCouName_ClgCouId(clgid, couid);
                            if (tab3.Rows.Count > 0)
                            {
                                dt["PriorityNo"] = j + 1;
                                dt["CollegeName"] = tab3.Rows[0]["CollegeName"].ToString();
                                dt["CourseName"] = tab3.Rows[0]["CourseName"].ToString();
                                t_details.Rows.Add(dt);
                            }
                        }
                    }
                    else
                    {
                        //if any error msg
                    }
                }
                else
                {
                    Panel1.Visible = true;
                }

                //************************************************************************************
                if (t_details.Rows.Count > 0)
                {
                    GVpriority.DataSource = t_details;
                    GVpriority.DataBind();
                }
                else
                {
                    // add option entry
                    for (int i = 1; i <= 20; i++)
                    {
                        ListItem L = new ListItem(i.ToString());
                        DDLcount.Items.Add(L);
                    }
                    DDLcount.Items.Insert(0, "-- Select --");
                    Panel1.Visible = true;
                }
            }
        }
        protected void DDLcount_SelectedIndexChanged(object sender, EventArgs e)
        {
            Panel2.Visible = true;
            int priorCount = int.Parse(DDLcount.SelectedItem.Text);
            DataTable t_proirNo = new DataTable();
            t_proirNo.Columns.Add("PriorityNo", typeof(int));
            for (int i = 1; i <= priorCount; i++)
            {
                DataRow dt = t_proirNo.NewRow();
                dt["PriorityNo"] = i.ToString();
                t_proirNo.Rows.Add(dt);
            }
            DLpriority.DataSource = t_proirNo;
            DLpriority.DataBind();
            foreach (DataListItem item in DLpriority.Items)
            {
                DropDownList ddlCity = (DropDownList)item.FindControl("DDLcity");
                ddlCity.DataSource = b.Cities_GetAll();
                ddlCity.DataTextField = "CityName";
                ddlCity.DataValueField = "CityId";
                ddlCity.DataBind();
                ddlCity.Items.Insert(0, "Select");
                DropDownList ddlClg = (DropDownList)item.FindControl("DDLcollege");
                //ddlClg.DataSource = b.College_GetAll();
                //ddlClg.DataTextField = "CollegeName";
                //ddlClg.DataValueField = "CollegeId";
                //ddlClg.DataBind();
                ddlClg.Items.Insert(0, "Select");
                DropDownList ddlCou = (DropDownList)item.FindControl("DDLcourse");
                //ddlCou.DataSource = b.Course_GetAll();
                //ddlCou.DataTextField = "CourseName";
                //ddlCou.DataValueField = "CourseId";
                //ddlCou.DataBind();
                ddlCou.Items.Insert(0, "Select");
            }
        }
        protected void DDLcity_SelectedIndexChanged(object sender, EventArgs e)
        {
            DropDownList ddlCity = (DropDownList)sender;
            if (ddlCity.SelectedIndex != 0)
            {
                int cityid = int.Parse(ddlCity.SelectedItem.Value);
                var row = (DataListItem)ddlCity.NamingContainer;
                DropDownList ddlCollege = (DropDownList)row.FindControl("DDLcollege");
                ddlCollege.DataSource = b.College_GetAll_CityId(cityid);
                ddlCollege.DataTextField = "CollegeName";
                ddlCollege.DataValueField = "CollegeId";
                ddlCollege.DataBind();
                ddlCollege.Items.Insert(0, "select");
            }
            else
            {
                var row = (DataListItem)ddlCity.NamingContainer;
                DropDownList ddlCollege = (DropDownList)row.FindControl("DDLcollege");
                ddlCity.SelectedIndex = 0;
                Response.Write("<script>alert('Please Select City')</script>");
                ddlCollege.Items.Clear();
                ddlCollege.Items.Insert(0, "Select");
            }
        }
        protected void DDLcollege_SelectedIndexChanged(object sender, EventArgs e)
        {
            DropDownList ddlCollege = (DropDownList)sender;
            if (ddlCollege.SelectedIndex != 0)
            {
                int clgid = int.Parse(ddlCollege.SelectedItem.Value);
                var row = (DataListItem)ddlCollege.NamingContainer;
                DropDownList ddlCourse = (DropDownList)row.FindControl("DDLcourse");
                ddlCourse.DataSource = b.ClgCourse_GetAll_ClgId(clgid);
                ddlCourse.DataTextField = "CourseName";
                ddlCourse.DataValueField = "CourseId";
                ddlCourse.DataBind();
                ddlCourse.Items.Insert(0, "select");
            }
            else
            {
                var row = (DataListItem)ddlCollege.NamingContainer;
                DropDownList ddlCourse = (DropDownList)row.FindControl("DDLcourse");
                ddlCollege.SelectedIndex = 0;
                Response.Write("<script>alert('Please Select College')</script>");
                ddlCourse.Items.Clear();
                ddlCourse.Items.Insert(0, "Select");
            }
        }
Sumit Kesarwani

Sumit Kesarwani

21-Nov-2014
Hi Rashmi, 
I think you try to create the cascading dropdownlist, you can try the following code:

UI Code:
<div>
     <div>
           <label>City : </label>
                <asp:DropDownList  ID="DDLCity"runat="server"AutoPostBack="True"OnSelectedIndexChanged="DDLCity_SelectedIndexChanged"  ></asp:DropDownList>
            </div>
            <br/>
            <div>
                <label>College : </label>
                <asp:DropDownList  ID="DDLCollege"  runat="server"AutoPostBack="True"></asp:DropDownList>
            </div>
        </div>

Class:

publicclassCity
    {
        publicint Id { get; set; }
        publicstring CityName { get; set; }
        publicstring College { get; set; }
    }

Code Behind:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
 
namespace CascadingDropdownAspNet
{
    publicpartialclassDefault : System.Web.UI.Page
    {
        publicList<City> Cities = newList<City>();
 
        protectedvoid Page_Load(object sender, EventArgs e)
        {
            Cities.Add(newCity { Id = 1, CityName = "New York", College = "New York College 1" });
            Cities.Add(newCity { Id = 2, CityName = "New York", College = "New York College 2" });
            Cities.Add(newCity { Id = 3, CityName = "Boston", College = "Boston College 1" });
            Cities.Add(newCity { Id = 4, CityName = "Boston", College = "Boston College 2" });
 
            if (!IsPostBack)
            {
                DDLCity.Items.AddRange(Cities.Select(x => newListItem(x.CityName)).Distinct().ToArray());
 
            }
        }
 
        protectedvoid DDLCity_SelectedIndexChanged(object sender, EventArgs e)
        {
            DDLCollege.Items.Clear();
            var selectedItem = DDLCity.SelectedItem.ToString();
 
            DDLCollege.Items.AddRange(Cities.Where(x => x.CityName == selectedItem).Select(x => newListItem(x.College)).ToArray());
        }
    }
}



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