Web service AJAX Cascade dropdown ตำบล อำเภอ จังหวัด

คร่าว ๆ นะครับ

ส่วนแรก หน้า aspx

<ajaxToolkit:ToolkitScriptManager runat="Server" EnableScriptGlobalization="true"EnableScriptLocalization="true" ID="ScriptManager1" /><asp:DropDownList ID="DropDownList1" runat="server"></asp:DropDownList><asp:DropDownList ID="DropDownList2" runat="server"></asp:DropDownList><asp:DropDownList ID="DropDownList3" runat="server"></asp:DropDownList><br /><ajaxToolkit:CascadingDropDown ID="CascadingDropDown1" runat="server" TargetControlID="DropDownList1" ServicePath="CommonService.asmx" ServiceMethod="GETPROVINCE" Category="Province"PromptText="เลือกจังหวัด" LoadingText="กำลังอ่านข้อมูล..."></ajaxToolkit:CascadingDropDown>

<ajaxToolkit:CascadingDropDown ID="CascadingDropDown2" runat="server" TargetControlID="DropDownList2"ServicePath="CommonService.asmx" ServiceMethod="GETAMPHUR"ParentControlID="DropDownList1"Category="Amphur" PromptText="เลือกอำเภอ" LoadingText="กำลังอ่านข้อมูล..." ></ajaxToolkit:CascadingDropDown>
<ajaxToolkit:CascadingDropDown ID="CascadingDropDown3" runat="server" TargetControlID="DropDownList3"ServicePath="CommonService.asmx" ServiceMethod="GETTUMBOL" ParentControlID="DropDownList2"Category="GETTUMBOL" PromptText="เลือกตำบล" LoadingText="กำลังอ่านข้อมูล..." ></ajaxToolkit:CascadingDropDown>

ส่วนที่สอง ส่วนของ  Web Service

public class CommonService : System.Web.Services.WebService{    public CommonService()    {         //Uncomment the following line if using designed components         //InitializeComponent();     }    public string ConnStr = ConfigurationManager.ConnectionStrings["TestDB"].ConnectionString;    [WebMethod(EnableSession = true)]    public CascadingDropDownNameValue[] GETPROVINCE(string knownCategoryValues, string category)    {        SqlConnection myConnection = new SqlConnection(ConnStr);        SqlCommand myCommand = new SqlCommand("select '1',changwatname,provinceid from changwat where provinceid= @provinceid union select '2',changwatname,provinceid from changwat", myConnection);        myCommand.CommandType = CommandType.Text;         myCommand.Parameters.AddWithValue("@provinceid", "32" /*provinceid*/);        myConnection.Open();        List<CascadingDropDownNameValue> values = new List<CascadingDropDownNameValue>();        using (SqlDataReader reader = myCommand.ExecuteReader())        {             while (reader.Read())            {                values.Add(new CascadingDropDownNameValue((string)reader["changwatname"], reader["provinceid"].ToString()));            }            myConnection.Close();            return values.ToArray();        }    }

    [WebMethod]    public CascadingDropDownNameValue[] GETAMPHUR(string knownCategoryValues, string category)    {        StringDictionary kv = CascadingDropDown.ParseKnownCategoryValuesString(   knownCategoryValues);        int Provinceid;        if (!kv.ContainsKey("Province") ||            !Int32.TryParse(kv["Province"], out Provinceid))        {            return null;        }

         SqlConnection myConnection = new SqlConnection(ConnStr);        SqlCommand myCommand = new SqlCommand("select '1',amphurname,cityid from amphur where provinceid= @provinceid and cityid is not null /*union select '2',amphurname,cityid from amphur where cityid is not null*/", myConnection);        myCommand.CommandType = CommandType.Text;        myCommand.Parameters.AddWithValue("@provinceid", Convert.ToString(Provinceid)); //"01" /*districtid*/);        myConnection.Open();
        List<CascadingDropDownNameValue> values = new List<CascadingDropDownNameValue>();        using (SqlDataReader reader = myCommand.ExecuteReader())        {            while (reader.Read())            {
                values.Add(new CascadingDropDownNameValue((string)reader["amphurname"], reader["cityid"].ToString()));            }        }        return values.ToArray();     }

    [WebMethod]    public CascadingDropDownNameValue[] GETTUMBOL(string knownCategoryValues, string category)    {        StringDictionary kv = CascadingDropDown.ParseKnownCategoryValuesString(   knownCategoryValues);        int Amphurid;        int Provinceid;        string a;        string b;        if (!kv.ContainsKey("Amphur"))        {            return null;        }        b = kv["Amphur"];        a = kv["Province"];        SqlConnection myConnection = new SqlConnection(ConnStr);        SqlCommand myCommand = new SqlCommand("select '1',tumbolname,districtid from tumbol where provinceid = @provinceid and cityid= @cityid ", myConnection);        myCommand.CommandType = CommandType.Text;        myCommand.Parameters.AddWithValue("@provinceid", Convert.ToString(a));        myCommand.Parameters.AddWithValue("@cityid", Convert.ToString(b)); //"01" /*districtid*/);        myConnection.Open();
        List<CascadingDropDownNameValue> values = new List<CascadingDropDownNameValue>();        using (SqlDataReader reader = myCommand.ExecuteReader())        {            while (reader.Read())            {                values.Add(new CascadingDropDownNameValue((string)reader["tumbolname"], reader["districtid"].ToString()));            }        }        return values.ToArray();    }

เสร็จออกมาแล้วจะได้เวปหน้าตาเยี่ยงนี้ครับ... พยายามเข้า