Unable to find control in detailsview template field

Question

I have encountered this error "Object reference not set to an instance of an object." when i trying to set a value which i had session from the previous page and set it on a template field. when I debugged it, the session value was there(successfully session over). what i am trying to do is to display the value of what I had session on detailsview.

aspx :

 <asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False">

    <Fields>
        <asp:TemplateField HeaderText="Order Number " SortExpression="poNum">

            <ItemTemplate>
                <asp:Label ID="test" runat="server" Text='<%# Bind("poNum") %>'></asp:Label>
            </ItemTemplate>

        </asp:TemplateField>

       </Fields>
    </asp:DetailsView>

code behind :

  protected void Page_Load(object sender, EventArgs e)
  {

    ((Label)DetailsView1.FindControl("test")).Text = Session["poNum"].ToString();
   }

I was wondering why I was unable to get the control from detailsview??

EDIT

    Label aaa = new Label();
    aaa.Text = Session["poNum"].ToString();

    Label orderNum = (Label)DetailsView1.FindControl("test"); // orderNum was null here 
    orderNum.Text = aaa.Text;

Well your code-behind has a *lot* of dereferencing in a single statement. I suggest you split it up using local variables. — Jon Skeet, Jan 19 '13 at 13:11
Hi, I had edited the codes as what u recommend, but they are still unable to find the control "test". — user1501969, Jan 19 '13 at 13:27
Right - but at least you know *which bit is causing the problem* now. — Jon Skeet, Jan 19 '13 at 13:27

score 1 · Accepted Answer · answered Jan 19 '13 at 13:24

1

You can access the Label in DataBound event of DetailsView.

answered Jan 19 '13 at 13:24

Memoizer

2,231
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but, i want to set the session value to detailsview when the page is loading. I had tried this before, but the code did not run the databound event. – user1501969 Jan 19 '13 at 13:25
It is fundamentally? Why don't you just bind session value to DetailsView? – Memoizer Jan 19 '13 at 13:32
Yes, i know where the problems lies now. The error would occur because I did not bind it ? After I tried to bind the Detailsview to an objectdatesource, the error was solved. Thanks! – user1501969 Jan 19 '13 at 13:35

score 0 · Answer 2 · answered Jan 19 '13 at 13:22

0

Are you calling FindControl before data binding the DetailsView? If so, it will return null - nothing there to find yet.

answered Jan 19 '13 at 13:22

Ray

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Hi, thanks for replying. I did not bind anything to detailsview. – user1501969 Jan 19 '13 at 13:24

Unable to find control in detailsview template field

2 Answers2