Question

I have three CascadingDropDowns on a webpage that I use in many places on my website. They’re loaded with Country, District and Area names from the database. I have successfully bound data with them and set them up to cascade. But I want to preselect three values in the three CascadingDropDowns when a user registers on my site.

After registration, I also need to see their data in the admin area, where I also need to preselect the three CascadingDropDowns with the values user selected. But I cannot figure out how to do this.

My Webservice code:

namespace ZetaSolutions.WebProjects.Web.Modules
{
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.Web.Script.Services.ScriptService()]
    public class PlaceSelection : System.Web.Services.WebService
    {
        [WebMethod]
        public CascadingDropDownNameValue[] BindCountryDropDown(string knownCategoryValues, string category)
        {
            SqlConnection conCountry = new SqlConnection(ZetaConfig.ConnectionString);
            conCountry.Open();

            SqlCommand cmdCountry = new SqlCommand("SELECT * FROM Country ORDER BY Name", conCountry);
            SqlDataAdapter daCountry = new SqlDataAdapter(cmdCountry);
            cmdCountry.ExecuteNonQuery();

            DataSet dsCountry = new DataSet();
            daCountry.Fill(dsCountry);
            conCountry.Close();

            List<CascadingDropDownNameValue> countryDetails = new List<CascadingDropDownNameValue>();

            foreach (DataRow dtRow in dsCountry.Tables[0].Rows)
            {
                string countryId = dtRow["CountryID"].ToString();
                string countryName = dtRow["Name"].ToString();

                countryDetails.Add(new CascadingDropDownNameValue(countryName, countryId));
            }

            return countryDetails.ToArray();
        }

        [WebMethod]
        public CascadingDropDownNameValue[] BindDistrictDropDown(string knownCategoryValues, string category)
        {
            int countryId;
            StringDictionary countryDetails = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
            countryId = Convert.ToInt32(countryDetails["Country"]);

            SqlConnection conDistrict = new SqlConnection(ZetaConfig.ConnectionString);
            conDistrict.Open();
            SqlCommand cmdDistrict = new SqlCommand("SELECT * FROM District WHERE CountryID=@CountryID ORDER BY Name", conDistrict);
            cmdDistrict.Parameters.AddWithValue("@CountryID", countryId);
            cmdDistrict.ExecuteNonQuery();

            SqlDataAdapter daDistrict = new SqlDataAdapter(cmdDistrict);
            DataSet dsDistrict = new DataSet();
            daDistrict.Fill(dsDistrict);
            conDistrict.Close();

            List<CascadingDropDownNameValue> districtDetails = new List<CascadingDropDownNameValue>();

            foreach (DataRow dtDistrictRow in dsDistrict.Tables[0].Rows)
            {
                string districtId = dtDistrictRow["DistrictID"].ToString();
                string districtName = dtDistrictRow["Name"].ToString();
                districtDetails.Add(new CascadingDropDownNameValue(districtName, districtId));
            }

            return districtDetails.ToArray();
        }

        [WebMethod]
        public CascadingDropDownNameValue[] BindAreaDropDown(string knownCategoryValues, string category)
        {
            int districtId;
            StringDictionary districtDetails = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
            districtId = Convert.ToInt32(districtDetails["District"]);

            SqlConnection conArea = new SqlConnection(ZetaConfig.ConnectionString);
            conArea.Open();
            SqlCommand cmdArea = new SqlCommand("SELECT * FROM Area WHERE DistrictID=@DistrictID ORDER BY Name", conArea);
            cmdArea.Parameters.AddWithValue("@DistrictID ", districtId);
            cmdArea.ExecuteNonQuery();

            SqlDataAdapter daArea = new SqlDataAdapter(cmdArea);
            DataSet dsArea = new DataSet();
            daArea.Fill(dsArea);
            conArea.Close();

            List<CascadingDropDownNameValue> areaDetails = new List<CascadingDropDownNameValue>();

            foreach (DataRow dtAreaRow in dsArea.Tables[0].Rows)
            {
                string areaId = dtAreaRow["AreaID"].ToString();
                string areaName = dtAreaRow["Name"].ToString();
                areaDetails.Add(new CascadingDropDownNameValue(areaName, areaId));
            }

            return areaDetails.ToArray();
        }
    }
}

My aspx code:

<table>
    <tr>
        <td>
            Country:
        </td>
        <td>
            <asp:DropDownList ID="ddlCountry" runat="server"></asp:DropDownList>
            <ajaxToolkit:CascadingDropDown ID="CountryCascading" runat="server" Category="Country" TargetControlID="ddlCountry" LoadingText="Loading Countries..." PromptText="Select Country" ServiceMethod="BindCountryDropDown" ServicePath="PlaceSelection.asmx">
            </ajaxToolkit:CascadingDropDown>
        </td>
    </tr>
    <tr>
        <td>
            District:
        </td>
        <td>
            <asp:DropDownList ID="ddlDistrict" runat="server"></asp:DropDownList>
            <ajaxToolkit:CascadingDropDown ID="DistrictCascading" runat="server" Category="District" TargetControlID="ddlDistrict" ParentControlID="ddlCountry" LoadingText="Loading Districts..." PromptText="Select District" ServiceMethod="BindDistrictDropDown" ServicePath="PlaceSelection.asmx">
            </ajaxToolkit:CascadingDropDown>
        </td>
    </tr>
    <tr>
        <td>
            Area:
        </td>
        <td>
            <asp:DropDownList ID="ddlArea" runat="server"></asp:DropDownList>
            <ajaxToolkit:CascadingDropDown ID="AreaCascading" runat="server" Category="Area" TargetControlID="ddlArea" ParentControlID="ddlDistrict" LoadingText="Loading Areas..." PromptText="select Areas" ServiceMethod="BindAreaDropDown" ServicePath="PlaceSelection.asmx">
            </ajaxToolkit:CascadingDropDown>
        </td>
    </tr>
</table> 

Can anyone please tell me how can I solve my problem?

Answer 1

You will need to read the values in that you want to select from your ‘admin’ system and then use;

DropDownList.SelectedValue = "value";

on Page_Load with a postback check.

See : SelectedValue Property