Cascading Dropdown List in ASP.Net Using Entity Framework

Dorababu Meka

ASP.NET Entity FrameworkCascading Dropdown ListASP.Net using Entity Framework

6 Comments

Join the conversation! Your thoughts help the community grow.

Elena Mitevska9y ago
Great article. I would like to know how can i choose more then one options from dropdown?
Upendra Pratap Shahi10y ago
nice..
vishnu vardhan12y ago
no i am using if condition on page load event i.e if(!Page.IsPostBack){}
Dorababu Meka12y ago
Hi as per your post I may see that you are nor binding the dropdown in page_load event with if(!ispostback){//BindCombo}
vishnu vardhan12y ago
i already posted on questions but i didn't get any thing there pls .. give me some solution
vishnu vardhan12y ago
Hello Dorababu, I am working on some project there i have 2 drop down lists and one Textbox in Update panel1. here i am binding the Names of PG from database to dropdownlist1(DDPGNames) and binding the PG rooms to dropdownlist2(DDRoomNumber) based first dropdownlist (it's like Country and state thing) now if i select any Room number in 2nd Dropdownlist the room rent has to dispaly automatically in textbox. for this i am writing this code on DDRoomNumber SelectIndexChanged Event. but my problem is DDRoomNumber is not taking selected room Number (It is taking Only First Value) if i select any other room in dropdown list it's going first one only. see here my code: protected void DDRoomNumber_SelectedIndexChanged(object sender, EventArgs e) { txtRent.Enabled = true; MySqlConnection Con = new MySqlConnection(MyConString); MySqlCommand Cmd = Con.CreateCommand(); string S = "SELECT*FROM pg_room_list WHERE Room_Num ='" DDRoomNumber.SelectedItem.Text "' AND Room_PG_ID ='" DDPGNames.SelectedValue "';"; Cmd = new MySqlCommand(S, Con); MySqlDataReader Dr; Con.Open(); Dr = Cmd.ExecuteReader(); while (Dr.Read()) { string SRoom_Rent = Dr.GetString("Room_Rent"); txtRent.Text = SRoom_Rent; } Con.Close(); } Pls give me some solution. Thanks

This article shows how to work with a cascading dropdown list for country/state/city in ASP.Net using Entity Framework.

Create three tables as needed, as in:

CREATE TABLE country
(
countryID INT NOT NULL,
countryName varchar(50) NOT NULL,
PRIMARY KEY (countryID ),
);
CREATE TABLE state
(
stateID INT NOT NULL,
countryID INT NOTNULL,
stateName varchar(50) NOT NULL,
PRIMARY KEY (stateID ),
FOREIGN KEY (countryID ) REFERENCES country (countryID));
CREATE TABLE city
(
cityID INT NOT NULL,
stateID INT NOTNULL,
cityName varchar(50) NOT NULL,
PRIMARY KEY (cityID),
FOREIGN KEY (stateID) REFERENCES state (stateID));

First create an empty web application, as in:

Add a model as we did earlier and do the necessary

Add a web page to the solution and copy and paste this into the .aspx page:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="cascading.aspx.cs" Inherits="counrtybasedropdown.cascading" %>
<!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 id="Head1" runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<center>
<h3>
Cascading DropDownList for Country/State/City in ASP.Net</h3>
<table>
<tr>
<td>
Select a Country :
</td>
<td>
<asp:DropDownList ID="ddlCountry" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlCountry_SelectedIndexChanged">
</asp:DropDownList>
</td>
</tr>
<tr>
<td>
Select a State :
</td>
<td>
<asp:DropDownList ID="ddlState" runat="server" Enabled="false" AutoPostBack="true" OnSelectedIndexChanged="ddlState_SelectedIndexChanged">
</asp:DropDownList>
</td>
</tr>
<tr>
<td>
Select a City :
</td>
<td>
<asp:DropDownList ID="ddlCity" runat="server" Enabled="false">
</asp:DropDownList>
</td>
</tr>
</table>
</center>
</div>
</form>
</body>
</html>

Your .aspx.cs should be as follows:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace counrtybasedropdown
{
public partial class cascading : System.Web.UI.Page
{
Database1Entities dbEntity = new Database1Entities();
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
var country = from c in dbEntity.countries select new { c.countryID, c.countryName };
ddlCountry.DataSource = country.ToList();
ddlCountry.DataValueField = "countryID";
ddlCountry.DataTextField = "countryName";
ddlCountry.DataBind();
ddlCountry.Items.Insert(0, "--Select--");
}
}
protected void ddlCountry_SelectedIndexChanged(object sender, EventArgs e)
{
int countyID = Convert.ToInt16(ddlCountry.SelectedValue.ToString());
var state = from s in dbEntity.states where s.countryID.Equals(countyID) select new { s.stateID, s.stateName };
ddlState.DataSource = state.ToList();
ddlState.Enabled = true;
ddlState.DataValueField = "stateID";
ddlState.DataTextField = "stateName";
ddlState.DataBind();
ddlState.Items.Insert(0, "--Select--");
}
protected void ddlState_SelectedIndexChanged(object sender, EventArgs e)
{
int stateID = Convert.ToInt16(ddlState.SelectedValue.ToString());
var city = from c in dbEntity.cities where c.stateID.Equals(stateID) select new { c.cityID, c.cityName };
ddlCity.DataSource = city.ToList();
ddlCity.Enabled = true;
ddlCity.DataValueField = "cityID";
ddlCity.DataTextField = "cityName";
ddlCity.DataBind();
ddlCity.Items.Insert(0, "--Select--");
}
}
}

Happy coding.