Set selectedvalue for a dropdownlist using Javascript

Question

I have a dropdownlist that is populated by a webservice using the ajax cascading dropdown. I have not been able to set the selected value using javascript. It appears that the values do not exist when the javascript runs. I placed the javascript at the bottom of the aspx page. Any ideas. Here is all of the code and the javascript I have tried.

<asp:DropDownList ID="ddlBusinessArea" runat="server"></asp:DropDownList>
<cc1:CascadingDropDown ID="CascadingDropDown1" runat="server" TargetControlID="ddlBusinessArea" 
    Category="BusinessArea" ServiceMethod="GetBusinessArea" ServicePath="DropDownFilter.asmx" 
    LoadingText="Please Wait.....">
</cc1:CascadingDropDown>

<WebMethod()> _
Public Function GetBusinessArea() As CascadingDropDownNameValue()
    Dim values As New List(Of CascadingDropDownNameValue)()
    Dim objData As clsDataAccess = New clsDataAccess()
    Dim ds As DataSet = New DataSet
    Dim SQL = "select Description from tblvalidation where MyType = 'Business Area' order by description"
    ds = objData.SQLExecuteDataset(SQL)

    For Each dr As DataRow In ds.Tables(0).Rows
         values.Add(New CascadingDropDownNameValue(dr("Description"), dr("Description")))
    Next
    Return values.ToArray
End Function

<script type="text/javascript">

   var e = document.getElementById("<%=ddlBusinessArea.ClientID%>"); 
   e.options[e.selectedIndex].value = "12345"

  document.getElementById("<%=ddlBusinessArea.ClientID%>").value = "12345"
  document.getElementById("ctl00_ContentPlaceHolder2_ddlBusinessArea").value = "12345"
</script>

Brian Mains · Accepted Answer · 2011-02-04 16:22:50Z

1

No, you cannot set the value from code-behind; you would have to use JavaScript to set the selected value if binding from a web service. The web service binds everything after the server-side process runs and can only be affected by javascript.

HTH.

answered Feb 4, 2011 at 16:22

Brian Mains

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1 Comment

Mike Over a year ago

Any chance you can provide a code sample. Everything I have tried does not work. I added a javascript block to the bottom of the aspx page. It does not appear that the field options do not exist when the javascript runs.

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