Find controls in GridView - asp.net

Question

I have something weird happening, maybe i don't know of something?
I am trying to populate a Drop Down List (in the editItemTemplate) and also, when the Grid View Loads populate a column, with strings instead of the id's that it contains now.
ASPX(the fiels that I have problem with are &
<asp:GridView ID="gvAdminArticleAdd".....
<asp:TemplateField HeaderText="invsId" SortExpression="invsId">
<EditItemTemplate>
<asp:DropDownList ID="ddl_invNames" runat="server" AutoPostBack="True" />
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="lbl_insLabel" runat="server" Text='<%# Bind("invsId") %>'></asp:Label>
</ItemTemplate>
<FooterTemplate>
<asp:DropDownList ID="ddl_invNamesNew" runat="server" AutoPostBack="True" />
</FooterTemplate>
</asp:TemplateField>
CodeBehind
protected void gvAdminArticleAdd_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
//111111
//finding cotrols into the edit rows event
if (e.Row.RowState == DataControlRowState.Edit)
{
DropDownList ddlImages = (DropDownList)e.Row.FindControl("ddlImages");
ddlImages.DataSource = GetPdfs();
ddlImages.DataBind();
DropDownList ddlinvsNames = (DropDownList)e.Row.FindControl("ddl_invNames");
ArrayList invList = GetInvestigatorNames();
ddlinvsNames.DataSource = invList;
ddlinvsNames.DataBind();
}
//222222
//finding cotrols into rows
Label insLabel = (Label)e.Row.FindControl("lbl_insLabel");
int invsLabelId = int.Parse(insLabel.Text);
insLabel.Text = connection.GetInvsNameById(invsLabelId);
}
}
The problem that I have occur in the RowDataBound event, I can't figure it up what is wrong
//111111 and //22222 are working correctly(if I comment one of them), but not together. how can it be?
if I place them together I am getting an error on this line of code
int invsLabelId = int.Parse(insLabel.Text);
Object reference not set to an instance of an object.
so the error is in the previous line, but I can't figure why.

Answer 1

//111111 and //22222 are working correctly(if I comment one of them),
but not together. how can it be?
You do not need those two to work together. Only one will be available at a given time.
if (e.Row.RowState == DataControlRowState.Edit)
{
// EditItemTemplate - only controls inside EditItemTemplate are available here.
var ddlImages = (DropDownList)e.Row.FindControl("ddlImages");
var ddlinvsNames = (DropDownList)e.Row.FindControl("ddl_invNames");
}
else
{
// ItemTemplate - only controls inside ItemTemplate are available here.
var insLabel = (Label)e.Row.FindControl("lbl_insLabel");
}

Answer 2

The problem is that your dropDownList is added only during the EditMode. This you are retrieving in the if (e.Row.RowType == DataControlRowType.DataRow) code block. That is fine, you will be able to retrieve the dropdown list correctly. But in the same code block you are retrieving the Label ddl_invNames which will not be available in the edit mode, because you have added this label in the ItemTemplate. So the error must be in this place. However if you comment whole of this block, then the code goes directly to /222222, where you are trying to access the label, which will not be there at all during the edit mode of the row