Ajax Cascading DropDownList With Database Example in GridView

Ajax Cascading DropDownList With Database Example in GridView

several cases when we have two or three dropdowns in gridview and want second one (and third one) to be populated based on selection of first and second dropdownlist.

In this example i've implemented Ajax cascading drop down list in EditItemTemaplete of GridView for updation of records in grid by fetching data from database to populate dropdowns

First pur Put AjaxControlToolkit.dll in bin folder of your application.
Then After Set EventValidation  to false in page directive of your aspx page

use this web method or web service

[code]
[WebMethod]
public CascadingDropDownNameValue[] GetColorsForModel(
string knownCategoryValues,
string category)
[/code]



used name space

[code]
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using AjaxControlToolkit;
using System.Collections.Specialized;

[/code]

First of all add a new webservice and name it CascadingDropDown.asmx
In code behind of this asmx file write following code

[code]
/// <summary>
/// Summary description for CascadingDropDown
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService()]
public class CascadingDropDown : System.Web.Services.WebService
{
//Create global Connection string
string strConnection = ConfigurationManager.ConnectionStrings
["dbConnectionString"].ConnectionString;

public CascadingDropDown () {

//Uncomment the following line if using designed components
//InitializeComponent();
}
/// <summary>
/// WebMethod to populate country Dropdown
/// </summary>
/// <param name="knownCategoryValues"></param>
/// <param name="category"></param>
/// <returns>countrynames</returns>
[WebMethod]
public CascadingDropDownNameValue[] GetCountries
(string knownCategoryValues, string category)
{
//Create sql connection and sql command
SqlConnection con = new SqlConnection(strConnection);
SqlCommand cmd = new SqlCommand();
cmd.Connection = con;
cmd.CommandType = System.Data.CommandType.Text;
cmd.CommandText = "Select * from Country";

//Create dataadapter and fill the dataset
SqlDataAdapter dAdapter = new SqlDataAdapter();
dAdapter.SelectCommand = cmd;
con.Open();
DataSet objDs = new DataSet();
dAdapter.Fill(objDs);
con.Close();

//create list and add items in it
//by looping through dataset table
List<CascadingDropDownNameValue> countryNames
= new List<CascadingDropDownNameValue>();
foreach (DataRow dRow in objDs.Tables[0].Rows)
{
string countryID = dRow["CountryID"].ToString();
string countryName = dRow["CountryName"].ToString();
countryNames.Add(new CascadingDropDownNameValue
(countryName, countryID));
}
return countryNames.ToArray();


}

[WebMethod]
public CascadingDropDownNameValue[] GetCities
(string knownCategoryValues, string category)
{
int countryID;
//this stringdictionary contains has table with key value
//pair of cooountry and countryID
StringDictionary countryValues =
AjaxControlToolkit.CascadingDropDown.
ParseKnownCategoryValuesString(knownCategoryValues);
countryID = Convert.ToInt32(countryValues["Country"]);

SqlConnection con = new SqlConnection(strConnection);
SqlCommand cmd = new SqlCommand();
cmd.Connection = con;
cmd.CommandType = System.Data.CommandType.Text;
cmd.Parameters.AddWithValue("@CountryID", countryID);
cmd.CommandText =
"Select * from City where CountryID = @CountryID";

SqlDataAdapter dAdapter = new SqlDataAdapter();
dAdapter.SelectCommand = cmd;
con.Open();
DataSet objDs = new DataSet();
dAdapter.Fill(objDs);
con.Close();
List<CascadingDropDownNameValue> cityNames =
new List<CascadingDropDownNameValue>();
foreach (DataRow dRow in objDs.Tables[0].Rows)
{
string cityID = dRow["CityID"].ToString();
string cityName = dRow["CityName"].ToString();
cityNames.Add(new CascadingDropDownNameValue
(cityName, cityID));
}
return cityNames.ToArray();
}

}

[code]


use this code in aspx page
[code]

protected void GridView1_RowUpdating
(object sender, GridViewUpdateEventArgs e)
{
//Find dropdown to get selected Item text 
DropDownList ddlGridCountry = (DropDownList)
GridView1.Rows[e.RowIndex].FindControl("ddlCountry");
string strCountry =
ddlGridCountry.SelectedItem.Text.ToString();

DropDownList ddlGridCity = (DropDownList)
GridView1.Rows[e.RowIndex].FindControl("ddlCity");
string strCity =
ddlGridCity.SelectedItem.Text.ToString();

SqlDataSource1.UpdateParameters.Clear();
SqlDataSource1.UpdateParameters.Add
("Country", strCountry);
SqlDataSource1.UpdateParameters.Add("City", strCity);
}
[/code]