Dropdownlist using Ajax problem

• • Reply

  13 years ago

  by nuchphasu

  nuchphasu

  , Thailand

  Joined 13 years ago

  Hi
  I have a problem on Dropdownlist that connect database
  and retrieve data by Ajax.I write javascript like this
  
  

  -------------------------------------------------------------------------
  function ManageYear_onchange(machinetype)
  {
  
  

   var iManageYear=document.forms[0].ddlManageYear.selectedIndex;
   var vManageYear=document.forms[0].ddlManageYear[iManageYear].value; 
   clearDll("ddlEquipmentID");
   clearDll("ddlVendor");
      if(iManageYear!=0)
      {   
    AjaxFile.getEquipmentid(vManageYear,machinetype, GetEquipmentRecords_CallBack);
   }
      else
      {
    document.getElementById("ddlEquipmentID").selectedIndex=0;
    document.getElementById("ddlVendor").selectedIndex=0;
    return
      }
  
  
  
  
  
  
  
  
  
  
  
  
  

  }

  function GetEquipmentRecords_CallBack(response)
  {
      var ds = response.value;
      var i = 0;
      var iLength = 0;
      if (response.error != null){
          return;
      }
      if ((ds.Tables != null) && (ds.Tables[0].Rows.length > 0))
      {
   //insert data to dropdown
          for(i=0; i<ds.Tables[0].Rows.length; i++)
          {
              document.getElementById("ddlEquipmentID").options.add(new Option(ds.Tables[0].Rows[i]["EquipmentName"],ds.Tables[0].Rows[i]["EquipmentID"]))
          }
      }
  }
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  function clearDll(ddlname)
  {
   iLength=document.getElementById(ddlname).options.length;
   for(i=0; i<iLength; i++)
          {
              document.getElementById(ddlname).options[0] = null;
          }
          document.getElementById(ddlname).options.add(new Option("--กรุณาเลือก--",0));
  
  
  
  
  
  
  

  }
  -------------------------------------------------------------------------
  and i insert ManageYear_onchange() at code behind like this
  
  

  -------------------------------------------------------------------------
  Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
          'Put user code to initialize the page here
          Ajax.Utility.RegisterTypeForAjax(GetType(AjaxFile))
          If Not Me.IsPostBack Then
              Me._MachineType = Request.QueryString("MachineType")
              ddlManageYear.SelectedValue = clsUtil.DateTimeNow.Year
              ddlManageYear.Attributes.Add("onchange", "return ManageYear_onchange('" & Me._MachineType & "');")
              Me.RegisterStartupScript("startup", "<script> ManageYear_onchange('" & Me._MachineType & "');</script>")
          End If
      End Sub
  -------------------------------------------------------------------------
  
  
  
  
  
  
  
  
  
  
  

  on Ajax page i connect to server and send dataset like this

  -------------------------------------------------------------------------
      <Ajax.AjaxMethod()> _
  Public Function getEquipmentid(ByVal ManageYear As Integer, ByVal Machinetype As String) As DataSet
          Dim ds As New DataSet
          Dim aclsQuery As New clsDBSQLBased
          Dim selectQuery As String
  
  
  
  
  

  
          selectQuery = "select  distinct cast(e.EquipmentId as varchar) + ' : ' + e.[description] [EquipmentName],e.EquipmentId [EquipmentID] from Eim_Equipment e,Eit_ManageEquipment m " + _
          " where e.equipmentid=m.equipmentid and " & _
          " m.ManageYear=" & ManageYear & _
          " and e.MachineType='" & Machinetype & "'"
          ds = aclsQuery.GetDataSet(selectQuery)
          Return ds
  
  
  
  
  
  

      End Function
  -------------------------------------------------------------------------
  

  The error is when i click submit button
  after i was selected value from dropdown
  and postback to server .
  The selectedvalue is reset to the first data of dropdown(selectindex =0)
  I try to search and debug code (and debug javascript).
  Nothing wrong and now i don't know what to do if you can help me
  It's very helpful.Thanks.
  
  
  
  
  
  

  NC.

   

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