Add control to asp:PlaceHolder on asp.net page from user control on same page

Dan

unread,

Jan 2, 2004, 4:39:27 PM1/2/04

to

I have an asp.net page default.aspx with a user control and a placeholder
control.

In my user control I have 5 linkbuttons. I would like to have each of these
linkbuttons load a different user control into the placeholder on the
default.aspx page. Is this possible? If so how can I add my user controls
to the placeholder from another user control?

Thanks,

Dan

Alessandro Zifiglio

unread,

Jan 2, 2004, 6:27:14 PM1/2/04

to

hi dan,
a much better solution would be to have a controlID in your querystring.
This way you use a normal hyperlink control and pass a different id for
every
link that is click and then retrieve it on your default page and structure
out from there in page_load--this way you can load controls from the default
page itself.

so in default.aspx page load you can do something like this :
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
Dim controlID As String
Dim c1 As Control
controlID = Request.QueryString("controlID")
Select Case controlID
case "control1"
c1 = LoadControl("my_control_name.ascx")
PlaceHolder1.Controls.Add(c1)
case "control2"
c1 = LoadControl("my_control_name.ascx")
PlaceHolder1.Controls.Add(c1)
case "control3"
c1 = LoadControl("my_control_name.ascx")
PlaceHolder1.Controls.Add(c1)
case "control4"
c1 = LoadControl("my_control_name.ascx")
PlaceHolder1.Controls.Add(c1)
case "control5"
c1 = LoadControl("my_control_name.ascx")
PlaceHolder1.Controls.Add(c1)
case else
Dim lblerror As New Label()
lblerror.Text = "How did you get here ;)"
PlaceHolder1.Controls.Add(lblerror)
End select
End Sub

"Dan" <dand...@test.com> wrote in message
news:OuVnSfX0...@TK2MSFTNGP09.phx.gbl...

Dan

unread,

Jan 9, 2004, 2:56:45 PM1/9/04

to

Thanks for the suggestion, but I'm trying to use querystrings as a last
resort. Any other ideas?

Dan

"Alessandro Zifiglio" <alessandr...@NO-SPAM-hotmail.com> wrote in
message news:wcnJb.22943$i_5....@news.edisontel.com...

Alessandro Zifiglio

unread,

Jan 10, 2004, 10:56:32 AM1/10/04

to

My apologies dan, I misunderstood the question. What you want to do is very
simple. I misread your post. Look at the new code sample. Add it to your
buttons clickevent in your header1 usercontrol.

Dim placeholder1 As PlaceHolder
Dim c1 As Control
c1 = LoadControl("webusercontrol2.ascx")
placeholder1 = Me.Parent.FindControl("placeholder1")
placeholder1.Controls.Add(c1)

What you need to do is simply access your parent control, which is your page
hosting the control and find the control you are looking for, in your case a
placeholder. The find control method takes a string, so pass the id of your
place holder here. Once you got the reference to your place holder, simply
add the new usercontrol to it. However i suggest doing this in the page_load
event of your user control and not the click event of a button. This is
because you are dynamically adding a control to the page and dynamically
added controls need to be rebuilt after postback ;P

"Dan" <dand...@test.com> wrote in message

news:u75scmu1...@TK2MSFTNGP10.phx.gbl...

Alessandro Zifiglio

unread,

Jan 10, 2004, 2:08:16 PM1/10/04

to

Ok, rethinking the fact that dynamic controls do not preserve themselves
when the page is submitted, you must recreate your dynamic controls on each
postback, early in the page lifecycle, such as during the Page_Init event

a possible solution to your problem, that is if you still want to load
controls when a certain button is clicked in your usercontrol is to set a
flag once the control is loaded and then checking for this in the page_init
method of your usercontrol that loaded the control by using viewstate to set
the flag like this :
This will work nicely.

However since I am using viewstate as a flag, viewstate is not available in
page_init --but page_load is a good enough substitute :)

Now your control will be rebuilt even after postback, maintaining state
etc--

Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
Handles MyBase.Load
If Not viewstate("Control1") Is Nothing Then
Load_control1()
End If
End Sub

Private Sub Load_control1()

Dim placeholder1 As PlaceHolder
Dim c1 As Control
c1 = LoadControl("webusercontrol2.ascx")
placeholder1 = Me.Parent.FindControl("placeholder1")
placeholder1.Controls.Add(c1)

End Sub

Private Sub Button1_Click(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Button1.Click
Load_control1()
'now set the flag in viewstate
viewstate("Control1") = "Control1"
End Sub

"Alessandro Zifiglio" <alessandr...@NO-SPAM-hotmail.com> wrote in

message news:ImVLb.1434$nC1...@news.edisontel.com...

Dan

unread,

Jan 12, 2004, 5:51:53 PM1/12/04

to

Thank you very much for the suggestions. I will give them a try.

Dan

"Alessandro Zifiglio" <alessandr...@NO-SPAM-hotmail.com> wrote in

message news:M9YLb.1485$nC1...@news.edisontel.com...