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how to load the dropdownlist box without postback?

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  1 year ago

  by prabhu_samy

  prabhu_samy

  chennai, India

  Joined 2 years ago

   

  How to load the dropdownlist box without  postback?

   

  eg:

  if you choose country in one dropdown the corresponding states wil fetch in another dropdown without postback

  pls help.... 

   

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  1 year ago

  by m8mbl

  Man-Bun Lee

  , United Kingdom

  Joined 2 years ago

  Try this site:

  http://www.asp.net/ajax/

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  1 year ago

  by prabhu_samy

  prabhu_samy

  chennai, India

  Joined 2 years ago

   

  is it possible in javascript? 

   

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  1 year ago

  by prabhu_samy

  prabhu_samy

  chennai, India

  Joined 2 years ago

  Hi

   We can do it in javascript.

  I found out the following code to solving my problem.

   

  Javascript Code - ASPX page

  
  
  function Assign_State()
  {
  var id=  document.getElementById("DDLCountry").value;
  var select2 = document.Form1.DDLState;
  select2.options.length=0;
  select2.options[0] = new Option("--Select--","");
  if (id!="")
  {
  for(i=0;i
  {
  select2.options[i+1] = new Option(state_list[id][i],state_id_list[id][i]);
  }
                      }
  }
  function ShowID()
  {
  alert(document.getElementById("DDLState").value)
  return false;
  }
  
  

  ASPX - Body Content

  
  
  <table align="center">
  <tr>
  <td><asp:Label id="Label1" runat="server">Country List</asp:Label></td>
  <td><asp:DropDownList id="DDLCountry" runat="server"></asp:DropDownList></td>
  </tr>
  <tr>
  <td><asp:Label id="Label2" runat="server">State List</asp:Label></td>
  <td><asp:DropDownList id="DDLState" runat="server"></asp:DropDownList></td>
  </tr>
  <tr>
  <td></td>
  <td align="right"><asp:Button id="BtnShow" runat="server" Text="Show"></asp:Button></td>
  </tr>
  </table>
  
  
  

  ASPX - Code Behind

  
  Imports System.Data.OleDb
  Public Class FrmDynamicList
     Inherits System.Web.UI.Page
  #Region " Web Form Designer Generated Code "
  
     'This call is required by the Web Form Designer.
      Private Sub InitializeComponent()
  
     End Sub
     Protected WithEvents Label1 As System.Web.UI.WebControls.Label
     Protected WithEvents Label2 As System.Web.UI.WebControls.Label
     Protected WithEvents DDLCountry As System.Web.UI.WebControls.DropDownList
     Protected WithEvents DDLState As System.Web.UI.WebControls.DropDownList
     Protected WithEvents BtnShow As System.Web.UI.WebControls.Button
  
     'NOTE: The following placeholder declaration is required by the Web Form Designer.
     'Do not delete or move it.
     Private designerPlaceholderDeclaration As System.Object
  
     Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
         'CODEGEN: This method call is required by the Web Form Designer
         'Do not modify it using the code editor.
         InitializeComponent()
     End Sub
  
  #End Region
     Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
         DDLCountry.Attributes.Add("onchange", "Assign_State()")
         BtnShow.Attributes.Add("OnClick", "return ShowID()")
         If Not Page.IsPostBack Then
  
             Dim state_list As Hashtable
             Dim state_id_list As Hashtable
  
             Dim count As Integer
             Dim constr As String, sql As String
  
             Dim conn As OleDbConnection
             Dim ada As OleDbDataAdapter
             Dim country_ds As DataSet
  
             constr = "Provider=MSDAORA.1;User ID=1;Password=;Data Source=;Persist Security Info=True"
  
             Try
                 conn = New OleDbConnection(constr)
                 conn.Open()
  
                 state_list = New Hashtable
                 state_id_list = New Hashtable
  
                 sql = "Select * from test_country"
                 ada = New OleDbDataAdapter(sql, conn)
                 country_ds = New DataSet
                 ada.Fill(country_ds)
  
                 For count = 0 To country_ds.Tables(0).Rows.Count - 1
                     state_list.Add(country_ds.Tables(0).Rows(count)("country_id"), GetStringFromDS(country_ds.Tables(0).Rows(count)("country_id"), "state_name"))
                     state_id_list.Add(country_ds.Tables(0).Rows(count)("country_id"), GetStringFromDS(country_ds.Tables(0).Rows(count)("country_id"), "state_id"))
                 Next
  
                 ConvertToJsArray(state_list, "state_list")
                 ConvertToJsArray(state_id_list, "state_id_list")
  
                 Dim dr As DataRow = country_ds.Tables(0).NewRow
                 dr(1) = "--Select--"
                 country_ds.Tables(0).Rows.InsertAt(dr, 0)
                 DDLCountry.DataSource = country_ds
                 DDLCountry.DataValueField = "country_id"
                 DDLCountry.DataTextField = "country_name"
                 DDLCountry.DataBind()
             Catch ex As Exception
                 Response.Write(ex.Message)
             Finally
                 conn.Close()
                 conn = Nothing
             End Try
         End If
     End Sub
     Private Function GetStringFromDS(ByVal id As String, ByVal field As String) As String
         Dim constr As String, sql As String, state_list As String
         constr = "Provider=MSDAORA.1;User ID=;Password=;Data Source=;Persist Security Info=True"
         Dim conn As OleDbConnection
         Dim ada As OleDbDataAdapter
         Dim state_ds As DataSet
         Dim count As Integer
  
         Try
             conn = New OleDbConnection(constr)
             conn.Open()
             sql = "Select " & field & " from test_state where country_id=" & id
             ada = New OleDbDataAdapter(sql, conn)
             state_ds = New DataSet
             ada.Fill(state_ds)
             For count = 0 To state_ds.Tables(0).Rows.Count - 1
                 state_list = state_list & "'" & state_ds.Tables(0).Rows(count)(field) & "'" & ","
             Next
             state_list = Mid(state_list, 1, Len(state_list) - 1)
             GetStringFromDS = state_list
         Catch ex As Exception
             Response.Write(ex.Message)
         Finally
             conn.Close()
             conn = Nothing
         End Try
     End Function
     Function ConvertToJsArray(ByVal State_list As Hashtable, ByVal array_name As String)
         Dim script_array As String
         script_array = Chr(13) & " " & Chr(13)
         script_array = script_array & array_name & "= new  Array(" & State_list.Count & ")" & Chr(13)
         Try
             Dim myEnumerator As IDictionaryEnumerator = State_list.GetEnumerator()
             While myEnumerator.MoveNext()
                 script_array = script_array & array_name & "['" & myEnumerator.Key & "'] = new  Array(" & myEnumerator.Value & ")" & Chr(13)
             End While
             script_array = script_array & " "
             Response.Write(script_array)
         Catch ex As Exception
             Response.Write(ex.Message)
         End Try
     End Function
  End Class
  
  
  

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  1 year ago

  by udp

  udp

  , Israel

  Joined 1 year ago

  Hi Jeganeedi,

  I am also trying to acheive the samething.Ur code is so useful, I am beginner in .net and Javascripts. I tried to use ur code in my usercontrol. I am getting error in javascript at state_list[id][i] as undeclared. How u r passing those values in the javascript. Can u please help me in this.

   

  Thanks,

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  1 year ago

  by marinakn

  Marina Keshyan

  , United States

  Joined 1 year ago

  I got the same error 'state_list' is undefined. Any help?

  Jas

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  1 year ago

  by flydude

  flydude

  , Nigeria

  Joined 1 year ago

  thnx

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  1 year ago

  by kimsea

  kimsea

  , Cambodia

  Joined 3 years ago
  It's great code sample. Thank you, Kimsea
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