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.

> public int DisplayOrder {
> get {

>>>>>> return (int) ViewState["DisplayOrder"];

> }

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]

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.sorry.com> wrote in message
news:ekV8kZzODHA.1072@TK2MSFTNGP10.phx.gbl...

> Check out the Page.LoadControl method.
>
> RMD
>
> "David J. Berman" <David_Berman@bose.com> wrote in message
> news:ZjjKa.1$3j4.90@paloalto-snr1.gtei.net...

> > Thanks for any help...!
> >
> > My error is:
> > Object reference not set to an instance of an object.

> > > public int DisplayOrder {
> > > get {
> > >>>>>> return (int) ViewState["DisplayOrder"];
> > > }

> >
> >
> > 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]

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.sorry.com> wrote in message
news:ekV8kZzODHA.1072@TK2MSFTNGP10.phx.gbl...

> Check out the Page.LoadControl method.
>
> RMD
>
> "David J. Berman" <David_Berman@bose.com> wrote in message
> news:ZjjKa.1$3j4.90@paloalto-snr1.gtei.net...

> > Thanks for any help...!
> >
> > My error is:
> > Object reference not set to an instance of an object.

> > > public int DisplayOrder {
> > > get {
> > >>>>>> return (int) ViewState["DisplayOrder"];
> > > }

> >
> >
> > 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!
> >
> >

>
>