Hello

I'm getting this error with a dropdownlist in one of my pages. 

I'm going to try to explain how I get it...

I have a page with 2 iframes, in one I choose a record from a grid, pass the value by querystring to the second frame, where I have a dropdownlist databinded to a sqldatasource. Then I set dropdownlist.selectedvalue = request.querystring("ID"). So far, so good...

The problem is that I have a "Next" and a "Previous" button to navigate through the dopdownlist records. When I hit one of them I get the error The 'SelectedIndex' and 'SelectedValue' attributes are mutually exclusive. Here's my code of one of the buttons:

    Protected Sub btNext_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btNext.Click
        If Me.ddImage.SelectedIndex + 1 <> Me.ddImage.Items.Count Then
            Me.ddImage.SelectedIndex = Me.ddImage.SelectedIndex + 1
            Me.frmVal.Attributes("src") = "../ValScans/ValScanSum.aspx?ID=" & Me.ddImage.SelectedValue
            Me.frmImage.Attributes("src") = "../ValScans/Image.aspx?ID=" & Me.ddImage.SelectedValue
            Me.btPrevious.Enabled = True
            Me.btNext.Enabled = True
        Else
            Me.btNext.Enabled = False
        End If

        If Me.ddImage.SelectedIndex + 1 = Me.ddImage.Items.Count Then
            Me.btNext.Enabled = False
        End If
    End Sub

 The strange is that if I run the page without choosing one ID from the other iframe, I don't get the error. And also, when I debug the code, I get exactly the same values from the dropdownlist SelectedIndex and SelectedValue.

I'm really clueless! I've searched the net for answers, but none answers my problem.

Thank's a lot

Paula
 

You might be running into a problem because you are setting the selectedValue and SelectedIndex in the same postback ....
Exactly what line are you getting the error?
What you might try doing is clearing the selection before you set the index

 Hello PureWeen

Thank you very much for your answer.

I tried all your sugestions, but none worked.

I found the line that's causing the error:

            Me.ddImage.SelectedIndex = Me.ddImage.SelectedIndex + 1

 Is there another way to get the previous/next record of the dropdownlist?

I have code on the previous button, that is the same, except that I set "selectindex - 1".

And I have code on the SelectedIndexChange, that also has a strange behaviour... The SelectedIndex doesn't change, and It doubles the number of records on the dropdown!!!

    Protected Sub ddImage_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddImage.SelectedIndexChanged
        Me.frmVal.Attributes("src") = "../ValScans/ValScanSum.aspx?ID=" & Me.ddImage.SelectedValue
        Me.frmImage.Attributes("src") = "../ValScans/Image.aspx?ID=" & Me.ddImage.SelectedValue
        If Me.ddImage.SelectedIndex = 0 Then
            Me.frmVal.Attributes("src") = ""
            Me.frmImage.Attributes("src") = ""
        End If
        If Me.ddImage.SelectedIndex + 1 = Me.ddImage.Items.Count Then
            Me.btNext.Enabled = False
        Else
            Me.btNext.Enabled = True
        End If
    End Sub

  Am I going crazy, or this doesn't make any sense???

When I run the page without getting a ID by querystring, it functions normally!

Thank you

Paula 

What if anywhere you set the selectedindex you just do it like so

ddlImage.SelectedValue = ddlImage.Items[SOMENUMBER].Value

 Same error...

And the ID that I pass by querystring is not used on the sqldatasource. I only use it to set the ddImage.selectedValue = request.querystring("ID")  if a record was choosed on the other frame.

I don't know if it helps, but here's my Page Load code:

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Me.hfImage.Value = Request.QueryString("ID")

        If Request.QueryString("St") = "1" Then

            Me.radBeginDate.SelectedDate = Me.radBeginDate.MinDate
            Me.radEndDate.SelectedDate = Date.Now
            Me.btPrevious.Enabled = False
            Me.btNext.Enabled = True
            Me.frmVal.Visible = True
            Me.frmImage.Visible = True
            Me.frmVal.Attributes("src") = "../ValScans/ValScanSum.aspx?ID=" & Me.hfImage.Value
            Me.frmImage.Attributes("src") = "../ValScans/Image.aspx?ID=" & Me.hfImage.Value
            Dim dv As System.Data.DataView = CType(Me.sdsImages.Select(DataSourceSelectArguments.Empty), System.Data.DataView)
            Dim i As Integer = dv.Table.Rows.Count - 1
            If i >= 0 Then
                Dim dr As Data.DataRow = dv.Table.Rows(i)
                Dim dr_Begin As Data.DataRow = dv.Table.Rows(0)
                Me.radBeginDate.SelectedDate = Date.Parse(dr_Begin.Item("BeginDate")).ToShortDateString
                Me.radEndDate.SelectedDate = Date.Parse(dr.Item("EndDate")).ToShortDateString
            End If
            Me.ddImage.SelectedValue = Me.hfImage.Value
        End If

        If Me.ddImage.SelectedIndex = 0 Then
            Me.btPrevious.Enabled = False
        Else
            Me.btPrevious.Enabled = True
        End If

    End Sub

  Thank you

Paula 

well you are setting the selectedvalue of your dropdown in your page load every time the page loads which isn't good

do this

if not Page.IsPostBack
If Request.QueryString("St") = "1" Then
........
End If

End If

 Hi PureWeen

You're right, the error was caused because of the selectedValue on Page Load.

Note to myself, have a good night sleep before I post anything!

Since I couldn't use the page.IsPostBack instruction because that's indicate that a value is sent from the other frame, I replaced it by a session variable and change the value after I use it.

Thank's a lot for everything!

Paula 

I just had to say something.

It would appear that there are people all over the net suffering from this error message for want of it being worded better. I had given up and written a routine to search the for the correct index in my DropDownList and use SelectedIndex to make the selection in code, but looking through my code there was a solitary statement using "SelectedIndex"! It is a bit pathetic that you can only use one or the other during a single posting, but that does seem to be the cause of the problem.

Thanks!

 John