How do I dynamically create user controls?

[David J. Berman]

Thanks for any help...!

My error is:
Object reference not set to an instance of an object.[color=blue]
> public int DisplayOrder {
> get {[color=green][color=darkred]
>>>>>> return (int) ViewState["DisplayOrd er"];[/color][/color]
> }[/color]


Here's the setup:
I have made a user control that displays a persons picture. Its like this:

AccountName
[PICTURE]
< 1 of 3 >

You can click the arrows to navigate pictures. The control is smart - you
assign the AccountName property and it hits the database, maintains state
with ViewState. I can put several of them on one page if I put them there
statically. When I do this dynamically, I get the above error.

Question:
I have made a repeater which takes a dataset that has a list of account
names in it. It creates one instance of my control for each name in the
list. My controls appear and render correctly. However, I get the above
error when you click on my navigation buttons. Part of the problem is each
instance of my user control has the same ID.

#1 - How can I get the repeater to assign a unique id for each control?

#2 - Is it the case that the state information won't be managed for me
because my controls are dynamic?

When I put multiple instances of my control statically on a page, it works
fine. When its in the repeater, it renders fine but then clicking on the
nav buttons to navigate pictures produces the error.

Thank you so much!

[David J. Berman]

Re: How do I dynamically create user controls?

Thanks for the tip! I read about this on MSDN, google'd some examples and I
was able to get it to work. However, there is a glitch:

Suppose I have 10 instances of my picture control with the navigation
buttons underneath (because each person can have multiple pictures). When I
click those buttons each control updates correctly, however, the page seems
to refresh and scroll to the top. Can I make it so that the page doesn't
refresh but the control repaints itself?

My architecture is to have a .aspx page with a PersonList user control
sitting on it. That control is passed a list of accountnames (arraylist)
and for each name it loads a PersonPicture user control dynamically and adds
it to the page.

Thanks!



"RMD" <rmd@nospam.sor ry.com> wrote in message
news:ekV8kZzODH A.1072@TK2MSFTN GP10.phx.gbl...[color=blue]
> Check out the Page.LoadContro l method.
>
> RMD
>
> "David J. Berman" <David_Berman@b ose.com> wrote in message
> news:ZjjKa.1$3j 4.90@paloalto-snr1.gtei.net.. .[color=green]
> > Thanks for any help...!
> >
> > My error is:
> > Object reference not set to an instance of an object.[color=darkred]
> > > public int DisplayOrder {
> > > get {
> > >>>>>> return (int) ViewState["DisplayOrd er"];
> > > }[/color]
> >
> >
> > Here's the setup:
> > I have made a user control that displays a persons picture. Its like[/color][/color]
this:[color=blue][color=green]
> >
> > AccountName
> > [PICTURE]
> > < 1 of 3 >
> >
> > You can click the arrows to navigate pictures. The control is smart -[/color][/color]
you[color=blue][color=green]
> > assign the AccountName property and it hits the database, maintains[/color][/color]
state[color=blue][color=green]
> > with ViewState. I can put several of them on one page if I put them[/color][/color]
there[color=blue][color=green]
> > statically. When I do this dynamically, I get the above error.
> >
> > Question:
> > I have made a repeater which takes a dataset that has a list of account
> > names in it. It creates one instance of my control for each name in the
> > list. My controls appear and render correctly. However, I get the[/color][/color]
above[color=blue][color=green]
> > error when you click on my navigation buttons. Part of the problem is[/color]
> each[color=green]
> > instance of my user control has the same ID.
> >
> > #1 - How can I get the repeater to assign a unique id for each control?
> >
> > #2 - Is it the case that the state information won't be managed for me
> > because my controls are dynamic?
> >
> > When I put multiple instances of my control statically on a page, it[/color]
> works[color=green]
> > fine. When its in the repeater, it renders fine but then clicking on[/color][/color]
the[color=blue][color=green]
> > nav buttons to navigate pictures produces the error.
> >
> > Thank you so much!
> >
> >[/color]
>
>[/color]