Question

Can’t access the control in a listview

error

Object reference not set to an instance of an object.

.cs

public void lnkaddtocart_Command(Object sender, CommandEventArgs e)
{
  ((TextBox)ListView_ProductDetails.FindControl("txtbox_pqty")).Visible = false;   
}

.aspx

<asp:ListView runat="server" ID="ListView_ProductDetails">
     <LayoutTemplate>
        <asp:PlaceHolder ID="itemPlaceholder" runat="server"></asp:PlaceHolder>
     </LayoutTemplate>
     <ItemTemplate>
              <div class="qty">
                  Qty:
                  <asp:TextBox ID="txtbox_pqty" Text="1" runat="server"/>
                  <input type="hidden" name="product_id" size="2" value="41" />
                       <asp:LinkButton ID="lnkaddtocart" runat="server" 
                            CommandArgument='<%#Eval("pid") %>' 
                            OnCommand="lnkaddtocart_Command"  
                            cssclass="button">
                               <span>Add to Cart</span>
                        </asp:LinkButton>
                  </div>
    </ItemTemplate>
</asp:ListView>

Answer 1

You need to use FindControl on the NamingContainer of the TextBox which is the ListViewItem and not the ListView. Therefore you can use the LinkButton's NamingContainer property to find the ListViewItem.

var ctrl = (Control) sender;
var lvi = (ListViewItem) ctrl.NamingContainer;
var txt = (TextBox)lvi.FindControl("txtbox_pqty");
txt.Visible = false;