Setting a label value to a dropdownlist selected value

I am trying to set the value of a label to the selected value from a hidden dropdown list. This code is not working and the label value remians at its default.

Any ideas? Thanks very much.

Protected Sub DetailsView1_DataBound(ByVal sender As Object, ByVal e As System.EventArgs)

Dim mylabel As Label

Dim myddl As DropDownList

If (DetailsView1.CurrentMode = DetailsViewMode.ReadOnly) Then

mylabel = DetailsView1.FindControl(

"Label1")

myddl = DetailsView1.FindControl(

"DropDownListViewOffice")

mylabel.Text = myddl.SelectedValue.ToString

End If
0
cabby
7/31/2006 6:36:03 AM
asp.net.presentation-controls 72751 articles. 3 followers. Follow

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I have now put this code in the Page_Load sub as it wasn't being called before.

The code is:

Dim mylabel As New Label

Dim myddl As New DropDownList

If Page.IsPostBack = True Then

If (DetailsView1.CurrentMode = DetailsViewMode.ReadOnly) Then

mylabel =

CType(DetailsView1.FindControl("Label1"), Label)

myddl =

CType(DetailsView1.FindControl("DropDownListViewOffice"), DropDownList) 

mylabel.Text = myddl.SelectedValue.ToString

End If

End If

 

And the error I am getting is on the line:  mylabel.Text = myddl.SelectedValue.ToString

and the error is: System.NullReferenceException: Object reference not set to an instance of an object.

The code for the dropdown and the label from the item template is:

<ItemTemplate>

<asp:DropDownList Enabled="false" ID="DropDownListViewOffice" runat="server" SelectedValue='<%# Bind("Office") %>'

DataSourceID="SqlDataSource3" DataTextField="OfficeName" DataValueField="OfficeID">

</asp:DropDownList>

<asp:Label ID="Label1" runat="server" Text="Label" ></asp:Label>

</ItemTemplate>

I would be really happy to hear from anyone with some advise!!

Thanks

Clare

0
cabby
7/31/2006 11:47:23 AM

Clare,

Guess one or both controls are missing on Page_Load.

If I understand the goal you are trying to achieve perhaps this link helps:

http://forums.asp.net/thread/1309309.aspx


Greetings,

Sjonnie
0
Sjonnie2nd
7/31/2006 5:04:29 PM

Hi,

Thanks for the help. That other link is what I am trying to do but can I not use the way I have been trying already? What do you mean by the controls are missing on Page_load?

Thanks again.

Clare

0
cabby
8/2/2006 4:09:43 AM

Clare,

I dont use VB so I could be wrong: "Dim x as New Label (New DropDownlist)". Is the "New" needed? 

Anyway, I tried to simulate your code in a working example (be it in C#). Everything works without errors but..

When I put the code in Page_Load I noticed that at the end of Page_Load the debugger shows Label1.Text having the right value, but on rendering it keeps showing "Label". Enabling or disabling ViewState and with or without checking IsPostBack made no difference. When I put the code in Page_Databound everything works as expected.

So in the code you posted I see no reason for the null-reference error (except for perhaps the "New").

Anyone?


Greetings,

Sjonnie
0
Sjonnie2nd
8/2/2006 11:26:03 AM

Hi Sjonnie,

Thanks very much for helping with this. I have tried without 'new' and it makes no difference. When debugging the lines:

mylabel =

CType(DetailsView1.FindControl("Label1"), Label)

myddl =

CType(DetailsView1.FindControl("DropDownListViewOffice"), DropDownList)

dont seem to be getting a value, and so I am thinking maybe the problem is with the FindControl?

Does this hint at any other problem?

Thanks again for your help, really appreciate it.

Clare

0
cabby
8/2/2006 11:59:37 AM
Reply:

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