find control

Question

User-125499312 posted

i am having an issue to find controls from my code behind

here is my code

<asp:DropDownList ID="ddlGiftRegistryVendorAssociatedItemID1" runat="server" CssClass="BodyText2" style="width:180px;" />

<asp:DropDownList ID="ddlGiftRegistryVendorAssociatedItemID2" runat="server" CssClass="BodyText2" style="width:180px;" />

<asp:DropDownList ID="ddlGiftRegistryVendorAssociatedItemID3" runat="server" CssClass="BodyText2" style="width:180px;" />

<asp:DropDownList ID="ddlGiftRegistryVendorAssociatedItemID4" runat="server" CssClass="BodyText2" style="width:180px;" />

<asp:DropDownList ID="ddlGiftRegistryVendorAssociatedItemID5" runat="server" CssClass="BodyText2" style="width:180px;" />

<asp:DropDownList ID="ddlGiftRegistryVendorAssociatedItemID6" runat="server" CssClass="BodyText2" style="width:180px;" />

dim strGiftRegistryVendorAssociatedItemIDS  as string

For i = 1 To 6
strGiftRegistryVendorAssociatedItemIDS += CType(Me.Page.FindControl("ddlGiftRegistryVendorAssociatedItemID" + i.ToString), DropDownList).SelectedValue
Next

i am getting object refernce not set to an instane of an object

thx for ur help

Answer 1

User288213138 posted

Hi  yzidell,
 
  According to your description, I tried to reproduce your problem and found that I could find control according to the following method.

The code:

For i = 1 To 4
    Dim list As DropDownList = CType(Me.Page.FindControl("DropDownList" & i.ToString()), DropDownList)
    Response.Write(list.SelectedValue)
Next

The Result:
 
Best Regard,
Sam

Answer 2

User3690988 posted

If you are using a Master Page, then you have to find your controls in the ContentPlaceHolder.  For example, if your DDLs are enclosed in:

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

Then find your DDLs within the ContentPlaceHolder:

Dim strGiftRegistryVendorAssociatedItemIDS As String = String.Empty
Dim contnt As ContentPlaceHolder = DirectCast(Master.FindControl("MainContent"), ContentPlaceHolder)
For i = 1 To 6
  strGiftRegistryVendorAssociatedItemIDS += CType(contnt.FindControl("ddlGiftRegistryVendorAssociatedItemID" + i.ToString), DropDownList).SelectedValue & " "
Next