Simple Web Service Method for Generating Country, State and City in Dropdown List

Introduction

In this code snippet, I have shared the real time code which was working fine in my project to fill the country state and city based on the dropdown list items selected . Attached the source code in attachment section.

Aspx code

<table>
    <tr>
        <td>
            SelectCountry
        </td>
        <td>

            <asp:DropDownList ID="ddlCountry" runat="server" Width="100px">
            </asp:DropDownList>
            <ap:CascadingDropDown ID="CountryCascading" runat="server" Category="Country" TargetControlID="ddlCountry" LoadingText="Loading Countries..." PromptText="Select Country" ServiceMethod="BindCountry" ServicePath="~/Address_WebService.asmx">
            </ap:CascadingDropDown>

        </td>
    </tr>
    <tr>
        <td>
            SelectState
        </td>
        <td>
            <asp:DropDownList ID="ddlState" runat="server" Width="100px">
            </asp:DropDownList>
            <ap:CascadingDropDown ID="StateCascading" runat="server" Category="State" TargetControlID="ddlState" ParentControlID="ddlCountry" LoadingText="Loading States..." PromptText="Select State" ServiceMethod="BindState" ServicePath="~/Address_WebService.asmx"></ap:CascadingDropDown>

        </td>
    </tr>
    <tr>
        <td>
            SelectCity
        </td>
        <td>
            <asp:DropDownList ID="ddlCity" runat="server" Width="100px">
            </asp:DropDownList>

            <ap:CascadingDropDown ID="CityCascading" runat="server" Category="Region" TargetControlID="ddlCity" ParentControlID="ddlState" LoadingText="Loading Cities..." PromptText="selectCity" ServiceMethod="BindCity" ServicePath="~/Address_WebService.asmx"> </ap:CascadingDropDown>

            -
        </td>

    </tr>
</table>

Web service methods,

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
[System.Web.Script.Services.ScriptService]
public class Address_WebService: System.Web.Services.WebService
{
    SqlConnection conn = new SqlConnection(OneStopMethods_Common.constring_Property);
    [WebMethod]
    public CascadingDropDownNameValue[] BindCountry(string knownCategoryValues, string category)
    {
        DataSet ds = new DataSet();
        conn.Open();
        SqlCommand cmd = new SqlCommand("select * from SelectCountry", conn);
        SqlDataAdapter adp = new SqlDataAdapter(cmd);
        cmd.ExecuteNonQuery();
        adp.Fill(ds);
        conn.Close();
        List < CascadingDropDownNameValue > CountryDetails = new List < CascadingDropDownNameValue > ();
        foreach(DataRow DR in ds.Tables[0].Rows)
        {
            string CountryID = DR["CountryId"].ToString();
            string CountryName = DR["County"].ToString();
            CountryDetails.Add(new CascadingDropDownNameValue(CountryName, CountryID));
        }
        return CountryDetails.ToArray();
    }
    //Web method for bind state
    [WebMethod]
    public CascadingDropDownNameValue[] BindState(string knownCategoryValues, string category)
    {
        DataSet ds = new DataSet();
        int CountryID;
        StringDictionary CountryDetails = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
        CountryID = Convert.ToInt32(CountryDetails["Country"]);
        conn.Open();
        SqlCommand cmd = new SqlCommand("select * from SelectCountrySelectState where CountryId=@CountryID", conn);
        cmd.Parameters.AddWithValue("@CountryId", CountryID);
        cmd.ExecuteNonQuery();
        SqlDataAdapter adp = new SqlDataAdapter(cmd);
        adp.Fill(ds);
        conn.Close();
        List < CascadingDropDownNameValue > StateDetails = new List < CascadingDropDownNameValue > ();
        foreach(DataRow DR in ds.Tables[0].Rows)
        {
            string stateID = DR["StateId"].ToString();
            string statename = DR["State"].ToString();
            StateDetails.Add(new CascadingDropDownNameValue(statename, stateID));
        }
        return StateDetails.ToArray();
    }
    //Web method for bind city
    [WebMethod]
    public CascadingDropDownNameValue[] BindCity(string knownCategoryValues, string category)
    {
        DataSet ds = new DataSet();
        int stateID;
        StringDictionary statedetails = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
        stateID = Convert.ToInt32(statedetails["State"]);
        conn.Open();
        SqlCommand cmd = new SqlCommand("Select * from SelectStateSelectCity where StateId= " + stateID, conn);
        // cmd.Parameters.AddWithValue("@StateID", StateId)
        cmd.ExecuteNonQuery();
        SqlDataAdapter adp = new SqlDataAdapter(cmd);
        adp.Fill(ds);
        conn.Close();
        List < CascadingDropDownNameValue > CityDetails = new List < CascadingDropDownNameValue > ();
        foreach(DataRow DR in ds.Tables[0].Rows)
        {
            string CityID = DR["CityID"].ToString();
            string City = DR["City"].ToString();
            CityDetails.Add(new CascadingDropDownNameValue(City, CityID));
        }
        return CityDetails.ToArray();
    }
}