I have a section of my code that dynamically creates LinkButtons to allow
the user to go to the page containing a question they have not answered. The
code that creates the LinkButton is called, as well as the AddHandler line
(I ran a Debug and saw that it executes this code, and the links are
displayed on the page afterwards). However, the eventhandler is not called
when the LinkButton is clicked. Here is the code that dynamically generates
the LinkButtons as well as the eventhandler I want to be called:
'The code that generates the LinkButtons:
Private Sub btnSubmit_Click(ByVal sender As Object, ByVal e As
System.Web.UI.ImageClickEventArgs) Handles btnSubmit.Click
Me.submitanswers()
If Me.completetest() Then
'Code that I use to update my database, not involved in this
problem because Me.completetest() returns false
Else
Me.lblAnswered.Text = String.Format("{0} of 75 Questions
Answered (Not Answered: ", CStr(Me.questionsanswered()))
Dim myconnection As New
SqlConnection(System.Configuration.ConfigurationManager.AppSettings("connectionstring"))
Dim cmd As New SqlCommand("", myconnection)
Dim qnumreader As SqlDataReader
Dim insertafter As Integer =
Me.Form.Controls.IndexOf(Me.lblAnswered) + 1
For i As Integer = 1 To 75
cmd.CommandText = String.Format("SELECT
questions.questionnumber FROM useranswers INNER JOIN questions ON
useranswers.questionid=questions.questionid WHERE
questions.questionnumber={0} AND useranswers.testid={1} AND
useranswers.userid={2}", i, CStr(Session("testid")),
CStr(Session("userid")))
myconnection.Open()
qnumreader = cmd.ExecuteReader()
If Not qnumreader.Read() Then
Dim questionlink As New LinkButton()
questionlink.CausesValidation = False
questionlink.CommandArgument = i
questionlink.CssClass = "answerRED"
questionlink.EnableViewState = False
questionlink.Text = i & " "
AddHandler questionlink.Command, AddressOf
Me.QuestionLinkCommand
Me.Form.Controls.AddAt(insertafter, questionlink)
insertafter += 1
End If
myconnection.Close()
Next
Me.lblCloseParen.Visible = True
End If
End Sub
'The eventhandler I want to use:
Private Sub QuestionLinkCommand(ByVal sender As Object, ByVal e As
System.Web.UI.WebControls.CommandEventArgs)
Dim myconnection As New
SqlConnection(System.Configuration.ConfigurationManager.AppSettings("connectionstring"))
Dim cmd As New SqlCommand("SELECT subgroupid FROM questions WHERE
questionnumber=" & e.CommandArgument, myconnection)
myconnection.Open()
Session("subgroupid") = CInt(cmd.ExecuteScalar())
myconnection.Close()
End Sub
When I run my Application, the code in btnSubmit_Click works as I expect (or
at least it looks like it did), but when I click the dynamically created
LinkButtons (variable name questionlink), they postback but do not trigger
the QuestionLinkCommand method (the QuestionLinkCommand never gets executed
when I do a debug session). I cannot figure out why they are not triggering
this eventhandler, because I use AddHandler statements when creating the
LinkButtons, and the eventhandler has the correct signature. Is there
something I am doing wrong? Thanks.

Signature
Nathan Sokalski
njsokalski@hotmail.com
http://www.nathansokalski.com/
Charlie - 02 Oct 2007 03:03 GMT
Try changing the line
Dim questionlink As New LinkButton()
to
Dim WithEvents questionlink As New LinkButton()
Does that work?
> I have a section of my code that dynamically creates LinkButtons to allow
> the user to go to the page containing a question they have not answered. The
[quoted text clipped - 67 lines]
> LinkButtons, and the eventhandler has the correct signature. Is there
> something I am doing wrong? Thanks.
Nathan Sokalski - 02 Oct 2007 04:19 GMT
No, if I add the WithEvents keyword I recieve the message:
'WithEvents' is not valid on a local variable declaration.
That was a good suggestion (when I read your reply I thought that might be
it), but unfortunately it wasn't. Any other ideas? Thanks.

Signature
Nathan Sokalski
njsokalski@hotmail.com
http://www.nathansokalski.com/
> Try changing the line
>
[quoted text clipped - 85 lines]
>> LinkButtons, and the eventhandler has the correct signature. Is there
>> something I am doing wrong? Thanks.
Charlie - 02 Oct 2007 04:35 GMT
Put the declaration of questionlink outside of the btnSubmit_Click code
block, in the general declarations area...
public withevents questionlink as New LinkButton()
inside your codeblock, remove the dim questionlink line.
you could also scope the linkbutton as public or friend.
does that work?
> No, if I add the WithEvents keyword I recieve the message:
>
[quoted text clipped - 91 lines]
> >> LinkButtons, and the eventhandler has the correct signature. Is there
> >> something I am doing wrong? Thanks.
Cor Ligthert[MVP] - 02 Oct 2007 04:51 GMT
Nathan,
Here is a simple sample of dynamicly creating textboxes with events.
Will you be so kind if you send next time problems to these newsgroup to
show a simple sample instead of almost a complete sample. We want to help
you, however not doing a daytime job by investigating parts which are not
relevant to your question.
Cor
Cor Ligthert[MVP] - 02 Oct 2007 05:54 GMT
Sorry,
http://www.vb-tips.com/DynamicControl.aspx
rowe_newsgroups - 02 Oct 2007 11:42 GMT
> I have a section of my code that dynamically creates LinkButtons to allow
> the user to go to the page containing a question they have not answered. The
[quoted text clipped - 70 lines]
> Nathan Sokalski
> njsokal...@hotmail.comhttp://www.nathansokalski.com/
You apparently aren't to familiar with the programming modal of
ASP.NET? You need to use AddHandler to add the event listener before
the child control's event are handled (like in the Load event of the
Page), otherwise the dynamic event won't exist when it's time to
process it.
By the way, if you search the newsgroups before posting you could find
the answer on your own....
http://groups.google.com/group/microsoft.public.dotnet.framework.aspnet/search?h
l=en&group=microsoft.public.dotnet.framework.aspnet&q=dynamic+control+event&qt_g
=Search+this+group
Thanks,
Seth Rowe
Nathan Sokalski - 02 Oct 2007 16:55 GMT
The only way I can come up with to run this code in the Load event is to
create a Hidden control and have btnSubmit (the Button I am clicking to
cause the postback) assign it a value using JavaScript prior to doing the
postback. This would work, but I was hoping to not need to have extra
Controls for things like this. Is there a more efficient way, or am I stuck
with using an extra Hidden control? Thanks.

Signature
Nathan Sokalski
njsokalski@hotmail.com
http://www.nathansokalski.com/
>> I have a section of my code that dynamically creates LinkButtons to allow
>> the user to go to the page containing a question they have not answered.
[quoted text clipped - 93 lines]
>
> Seth Rowe
rowe_newsgroups - 02 Oct 2007 18:00 GMT
> The only way I can come up with to run this code in the Load event is to
> create a Hidden control and have btnSubmit (the Button I am clicking to
[quoted text clipped - 103 lines]
>
> > Seth Rowe
It seems to me after briefly reading your code segment you are only
creating one LinkButton. A simple approach would then be to add the
LinkButton at design time with it's Visible property set to false and
only show the LinkButton when it's necessary, and then hide it again
in it's event handler. Also, be sure to set EnableViewState to true to
preserve the Visible state on postbacks.
Something like:
///////////////
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As
System.EventArgs) Handles Button1.Click
Me.LinkButton1.Visible = True
End Sub
Protected Sub LinkButton1_Click(ByVal sender As Object, ByVal e As
System.EventArgs) Handles LinkButton1.Click
Try
'// My other code I want to run
Finally
Me.LinkButton1.Visible = False
End Try
End Sub
//////////////
P.S. It's easier on the responders if you just provide a short, easy
to read sample that demonstrates your problem. It's a pain to decipher
out the unrelated junk to just get to the problem.
Thanks,
Seth Rowe
rowe_newsgroups - 02 Oct 2007 18:08 GMT
> It seems to me after briefly reading your code segment you are only
> creating one LinkButton.
Nevermind, after rereading your post I now notice the For loop I
previously missed so disregard my post.
> P.S. It's easier on the responders if you just provide a short, easy
> to read sample that demonstrates your problem. It's a pain to decipher
> out the unrelated junk to just get to the problem.
As you can now see, useless clutter leads to pointless responses.
Thanks,
Seth Rowe
Nathan Sokalski - 02 Oct 2007 21:57 GMT
No, I am not just creating one LinkButton. If you missed it, the code that
creates the LinkButton is inside the loop that starts with:
For i As Integer = 1 To 75
There may, in some cases, only be one LinkButton, but depending on the
specific case there could be anywhere from 1-75 LinkButtons. If there were
never going to be more than about 5, I would probably do what you said and
simply change the properties, but that is unfortunately not the case here.

Signature
Nathan Sokalski
njsokalski@hotmail.com
http://www.nathansokalski.com/
>> The only way I can come up with to run this code in the Load event is to
>> create a Hidden control and have btnSubmit (the Button I am clicking to
[quoted text clipped - 144 lines]
>
> Seth Rowe
Cor Ligthert [MVP] - 03 Oct 2007 12:00 GMT
Nathan,
I gave you a link for a windowsform, because you were talking about a form
in my idea, but beside that there is as well a sample about a page.
This is a kind of calendar finding a date on a webpage.
http://www.vb-tips.com/ASPNetDynamicButton.aspx
Cor
Andrew Morton - 02 Oct 2007 11:52 GMT
> I have a section of my code that dynamically creates LinkButtons to
> allow the user to go to the page containing a question they have not
[quoted text clipped - 4 lines]
> is the code that dynamically generates the LinkButtons as well as the
> eventhandler I want to be called:
<snip>
You have to tell it to AutoPostBack. Incidentally, you can use "With" to
save a bit of typing:-
> If Not qnumreader.Read() Then
> Dim questionlink As New LinkButton()
With questionlink
.CausesValidation = False
.CommandArgument = i
.CssClass = "answerRED"
.EnableViewState = False
.Text = i & " "
.AutoPostBack = True
End With
> AddHandler questionlink.Command, AddressOf
> Me.QuestionLinkCommand
> Me.Form.Controls.AddAt(insertafter, questionlink)
> insertafter += 1
> End If
HTH
Andrew
Nathan Sokalski - 02 Oct 2007 16:48 GMT
This is a LinkButton, it does not need or have an AutoPostBack property. And
take note that in my original post I stated that it does do a PostBack, it
just doesn't trigger the eventhandler I attempted to assign it.

Signature
Nathan Sokalski
njsokalski@hotmail.com
http://www.nathansokalski.com/
>> I have a section of my code that dynamically creates LinkButtons to
>> allow the user to go to the page containing a question they have not
[quoted text clipped - 29 lines]
>
> Andrew
Andrew Morton - 03 Oct 2007 09:53 GMT
> This is a LinkButton, it does not need or have an AutoPostBack
> property.
My mistake.
> And take note that in my original post I stated that it
> does do a PostBack, it just doesn't trigger the eventhandler I
> attempted to assign it.
What errors are highlighted if you use Option Strict On? I ask because in
the handler you have
> Dim cmd As New SqlCommand("SELECT subgroupid FROM questions
> WHERE questionnumber=" & e.CommandArgument, myconnection)
which would give an error about not being able to use & with the
e.CommandArgument /object/, so there may be other errors you haven't
spotted.
Andrew
bruce barker - 02 Oct 2007 16:32 GMT
asp.net pages are stateless. you rendered the linkbuton and added to
handler on the click event. but when the user links on th button and the
asp.net is run again, the page does create th linkbutton and add the
handler, so the event is ignored.
your code needs to remember it added the linkbutton and handler during
previous postback and recreate the linkbutton and handler during the
oninit event. you can save your state in session or viewstate.
-- bruce (sqlwork.com)
> I have a section of my code that dynamically creates LinkButtons to allow
> the user to go to the page containing a question they have not answered. The
[quoted text clipped - 67 lines]
> LinkButtons, and the eventhandler has the correct signature. Is there
> something I am doing wrong? Thanks.