Disappearing usercontrol

[Grant Merwitz]

I am using usercontrols to control the contant in my website.
Currently, depending on a parameter passed in the querystring, the
appropriate usercontrol will be loaded.

i.e.
private void Page_Load(objec t sender, System.EventArg s e)
{
if(!Page.IsPost Back)
{
Switch(Request. Params["P"])
{
case "1" :
Control uc = LoadControl("/controls/control1.ascx") ;
pnlContent.Cont rols.Add(uc);
break;
case "2" :
Control uc = LoadControl("/controls/control2.ascx") ;
pnlContent.Cont rols.Add(uc);
break;
}
}
}

But now, when one of these control calls an internal method, the page posts
back and the control disappears.
I understand this i because the control is loaded through the code and is
not loaded again in the postback.

I have solved this problem by keeping the control in a session during post
backs, but am not completely sure if this is the right way to do things.

I have also tried to viewstate the control, but get the error:
The type 'ASP.control1_a scx' must be marked as Serializable or have a
TypeConverter other than ReferenceConver ter to be put in viewstate.
I have further tried to mark the control as Serializable which didn't seem
to help.

Can anyone suggest a better way of doing this, or a solution

Thanks

Grant

P.S. the control is not called control1.ascx, i just renamed it for this
example.

[Karl Seguin]

Re: Disappearing usercontrol

Typically you store the name of the control in the session or viewstate and
reuse that... something like:


string controlName = null;

if (!Page.IsPostBa ck){
switch(){
case "1":
controlName = "/controls/control1.ascx";
break;
case "2"
controlName = "/controls/control2.ascx";
break;
}
pnlContent.Cont rols.Add(Page.L oadControl(cont rolName));
ViewState.Add(" lastControl", controlName);
}ELSE{
controlName = (string)ViewSta te["lastContro l"];
if (controlName != null){
pnlContent.Cont rols.Add(Page.L oadControl(cont rolName));
}
}


Denis Bauer has an PlaceHolderCont rol which takes care of this, check it
out:

http://www.denisbauer.com/ASPNETControls/DynamicControlsPlaceholder.aspx

(free)

Karl
--
MY ASP.Net tutorials
http://www.openmymind.net/ - New and Improved (yes, the popup is
annoying)
http://www.openmymind.net/faq.aspx - unofficial newsgroup FAQ (more to
come!)
"Grant Merwitz" <grant@workshar e.com> wrote in message
news:OizGh5rNFH A.3988@tk2msftn gp13.phx.gbl...[color=blue]
> I am using usercontrols to control the contant in my website.
> Currently, depending on a parameter passed in the querystring, the
> appropriate usercontrol will be loaded.
>
> i.e.
> private void Page_Load(objec t sender, System.EventArg s e)
> {
> if(!Page.IsPost Back)
> {
> Switch(Request. Params["P"])
> {
> case "1" :
> Control uc = LoadControl("/controls/control1.ascx") ;
> pnlContent.Cont rols.Add(uc);
> break;
> case "2" :
> Control uc = LoadControl("/controls/control2.ascx") ;
> pnlContent.Cont rols.Add(uc);
> break;
> }
> }
> }
>
> But now, when one of these control calls an internal method, the page[/color]
posts[color=blue]
> back and the control disappears.
> I understand this i because the control is loaded through the code and is
> not loaded again in the postback.
>
> I have solved this problem by keeping the control in a session during post
> backs, but am not completely sure if this is the right way to do things.
>
> I have also tried to viewstate the control, but get the error:
> The type 'ASP.control1_a scx' must be marked as Serializable or have a
> TypeConverter other than ReferenceConver ter to be put in viewstate.
> I have further tried to mark the control as Serializable which didn't seem
> to help.
>
> Can anyone suggest a better way of doing this, or a solution
>
> Thanks
>
> Grant
>
> P.S. the control is not called control1.ascx, i just renamed it for this
> example.
>
>[/color]

[Grant Merwitz]

Re: Disappearing usercontrol

Brilliant, Thank You

So even if i'm reloading the control, the post back still holds strong.
I was under the impresson that if i had to reload the control, it would load
as if it were loading for the first time.
Hence why i tried to viewstate the whole control.

So i guess it all goes down to understanding how the .net page loads, and
that it will load the control, before attempting to do the postback within
the control.

Very interesting and thanks for your help


"Karl Seguin" <karl REMOVE @ REMOVE openmymind REMOVEMETOO . ANDME net>
wrote in message news:OJUdvDsNFH A.2748@TK2MSFTN GP09.phx.gbl...[color=blue]
> Typically you store the name of the control in the session or viewstate
> and
> reuse that... something like:
>
>
> string controlName = null;
>
> if (!Page.IsPostBa ck){
> switch(){
> case "1":
> controlName = "/controls/control1.ascx";
> break;
> case "2"
> controlName = "/controls/control2.ascx";
> break;
> }
> pnlContent.Cont rols.Add(Page.L oadControl(cont rolName));
> ViewState.Add(" lastControl", controlName);
> }ELSE{
> controlName = (string)ViewSta te["lastContro l"];
> if (controlName != null){
> pnlContent.Cont rols.Add(Page.L oadControl(cont rolName));
> }
> }
>
>
> Denis Bauer has an PlaceHolderCont rol which takes care of this, check it
> out:
> http://www.denisbauer.com/ASPNETCont...aceholder.aspx
> (free)
>
> Karl
> --
> MY ASP.Net tutorials
> http://www.openmymind.net/ - New and Improved (yes, the popup is
> annoying)
> http://www.openmymind.net/faq.aspx - unofficial newsgroup FAQ (more to
> come!)
> "Grant Merwitz" <grant@workshar e.com> wrote in message
> news:OizGh5rNFH A.3988@tk2msftn gp13.phx.gbl...[color=green]
>> I am using usercontrols to control the contant in my website.
>> Currently, depending on a parameter passed in the querystring, the
>> appropriate usercontrol will be loaded.
>>
>> i.e.
>> private void Page_Load(objec t sender, System.EventArg s e)
>> {
>> if(!Page.IsPost Back)
>> {
>> Switch(Request. Params["P"])
>> {
>> case "1" :
>> Control uc = LoadControl("/controls/control1.ascx") ;
>> pnlContent.Cont rols.Add(uc);
>> break;
>> case "2" :
>> Control uc = LoadControl("/controls/control2.ascx") ;
>> pnlContent.Cont rols.Add(uc);
>> break;
>> }
>> }
>> }
>>
>> But now, when one of these control calls an internal method, the page[/color]
> posts[color=green]
>> back and the control disappears.
>> I understand this i because the control is loaded through the code and is
>> not loaded again in the postback.
>>
>> I have solved this problem by keeping the control in a session during
>> post
>> backs, but am not completely sure if this is the right way to do things.
>>
>> I have also tried to viewstate the control, but get the error:
>> The type 'ASP.control1_a scx' must be marked as Serializable or have a
>> TypeConverter other than ReferenceConver ter to be put in viewstate.
>> I have further tried to mark the control as Serializable which didn't
>> seem
>> to help.
>>
>> Can anyone suggest a better way of doing this, or a solution
>>
>> Thanks
>>
>> Grant
>>
>> P.S. the control is not called control1.ascx, i just renamed it for this
>> example.
>>
>>[/color]
>
>[/color]