Thanks, Imar.

I got the code to work, but when I refreshed the page and ran the same code again, I got the following error message:

NullReferenceException was unhandled by user code
Object reference not set to an instance of an object.

Troubleshooting tips:
Use the "new" keyword to create an objct instance.
Check to determine if the objects is null before calling the method.
Get general help for this exception.


Thanks so much for your help...

Looks like the code can't find a control called Button1.

Is that defined in your page? What happens when you debug the app and set a break point at the line that retrieves the control? Do you get a valid reference?

Imar
---------------------------------------
Imar Spaanjaars
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
While typing this post, I was listening to: The Carnival Is Over by Nick Cave & the Bad Seeds (Track 14 from the album: Kicking Against the Pricks) What's This?

I am having a similar problem...

I have a web app that uses masterpages, a formview and a panel (within the formview). When I try to handle events for the controls within the formview (a button onclick event, for example), I am unable to access those controls. All controls that I am trying to reference are defined like this:

Dim ICarrier As DropDownList = fvCreateOrder.FindControl("ddlCarrier")

I tried dimming them using the same method that djpotte gives, but the result is the same.

All code I am using is in the code-behind for the page that the form is on (no stand-alone class files).

Anyone have any ideas?

Thanks!

Hi there,

Can you describe "I am unable to access those controls" in more detail? Do you get an exception, a null reference or are you controls not looking like the control you're expecting (e.g. not a true DropDownList, but a generic Control, for example?

Imar
---------------------------------------
Imar Spaanjaars
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.

Hey Imar,

"unable to access..." means that, in my code-behind, the variable declaration I gave above is unable to "see" those controls. I get the "Object Reference Not Set to an Instance of Object" message.

To get around this, I have removed the FormView & will be creating the connection to the database manually & feeding in the form values programmatically.

I know there has to be a way to do this, but I am under a bit of a time-crunch, so I will have to go with the manual route (unless you have another idea)?

Thanks!

Phil

Hi Phil,

Not sure why that wouldn't work. I can successfully do something like this in some Click event:

Button myButton = (Button)FormView1.FindControl("Button1");

with the following FormView:

<asp:FormView ID="FormView1" runat="server">
  <ItemTemplate>
    <asp:Button ID="Button1" runat="server" Text="Button" />
    <asp:TextBox ID="TextBox1" runat="server" />
  </ItemTemplate>
</asp:FormView>

Maybe your controls are in another container inside the ItemTemplate? Also, you need to cast your controls to the proper type...

Cheers,

Imar
---------------------------------------
Imar Spaanjaars
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.

I tried the solutions mentioned here but it's not working.

i have an image control in my formview which i need to programatically change, but i keep getting the "Object reference not set to an instance of an object" error. My code is below. can someone please help?

.ASPX FILE

<asp:Label ID="lblStudent_ID" runat="server" Text="Student ID" Font-Size="Small" Font-Names="Trebuchet MS"></asp:Label>  <asp:TextBox
            ID="txtStudent_ID" runat="server" Font-Size="Small" Font-Names="Trebuchet MS"></asp:TextBox>
        <asp:Button ID="btnSubmit" runat="server" Text="Submit" /><br /><br /></p>
<asp:FormView ID="FormViewMarksHeaders" runat="server" DataSourceID="MarksHeaders">
    <ItemTemplate>
    <p>
        <table width="100%" style="font-weight: bold">
            <tr>
                <td colspan="5"><asp:Image ID="imgCollege_Banner" runat="server" ImageUrl="~/Images/luzhou1.jpg" /><br /><br /></td>
            </tr>

.ASPX.VB FILE

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim imgChangeImage As Image
        imgChangeImage = CType(Me.FormViewMarksHeaders.FindControl("imgColl ege_Banner"), Image)
        imgChangeImage.ImageUrl = "~/Images/hubei.jpg"
End Sub


Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click
        Session("Roll") = txtStudent_ID.Text.ToUpper
        Response.Redirect("report2.aspx")
    End Sub

Hi there,

Does the ODS MarksHeaders return any results?

If there's no data coming from that control, your ItemTemplate with the image won't show up in the FormView and you end up with a null reference for the image.

Hope this helps,

Imar
---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.

Imar, I am trying to do the same in a FormView_ModeChanged event and get a NullReferenceException to the DropDownList. It works just find in FormView_Load. Any ideas?
Thanks.

Does your FormView already contain data when the event is fired? Maybe the event fires too soon, so there's no record and thus no drop down?

Imar
---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
Want to be my colleague? Then check out this post.