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

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

Dan
1/2/2004 3:39:27 PM

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

<html>
<body>
<form id="myform" method="post" runat="server" />
<PageHeader:Header id="header1" runat="server" />
<asp:PlaceHolder ID="content" runat="server" />
</form>
</body>
</html>

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
1/3/2004 12:27:14 AM

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

[quoted text, click to view]

Dan
1/9/2004 1:56:45 PM

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

Dan

"Alessandro Zifiglio" <alessandrozifiglio@NO-SPAM-hotmail.com> wrote in
message news:wcnJb.22943$i_5.18228@news.edisontel.com...
[quoted text, click to view]

Alessandro Zifiglio
1/10/2004 4:56:32 PM

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

[quoted text, click to view]

Alessandro Zifiglio
1/10/2004 8:08:16 PM

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" <alessandrozifiglio@NO-SPAM-hotmail.com> wrote in
message news:ImVLb.1434$nC1.287@news.edisontel.com...
[quoted text, click to view]

Dan
1/12/2004 4:51:53 PM

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

Dan

"Alessandro Zifiglio" <alessandrozifiglio@NO-SPAM-hotmail.com> wrote in
message news:M9YLb.1485$nC1.187@news.edisontel.com...
[quoted text, click to view]

Got something to say? Click here to post a reply to this thread.

Don't see what you're looking for? Try a search.

View other messages about asp.net building controls

View Other Months
June 2003
July 2003
August 2003
September 2003
October 2003
November 2003
December 2003
January 2004
February 2004
March 2004
April 2004
May 2004
June 2004
July 2004
August 2004
September 2004
October 2004
November 2004
December 2004
January 2005
February 2005
March 2005
April 2005
May 2005
June 2005
July 2005
August 2005
September 2005
October 2005
November 2005
December 2005
January 2006
February 2006
March 2006
April 2006
May 2006
June 2006
July 2006
August 2006
September 2006
October 2006
November 2006
December 2006
January 2007
February 2007
March 2007
April 2007
May 2007
June 2007
July 2007
August 2007
September 2007
October 2007
November 2007
December 2007
January 2008
February 2008
March 2008
April 2008
May 2008
June 2008

home · blog · groups

Questions? Comments? Contact the dn