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If i want to add a hidden field on the page, how can i check whether
that hidden field exists ?

for example if i do

If Page.FindControl("myhiddenfield") Is Nothing Then
Page.RegisterHiddenField("myhiddenfield", "hidden")
End If


Dim myHiddenField As HtmlInputHidden = Page.FindControl("myhiddenfield")
** this line would throw error


how can i know that the hidden field is there before trying to add it ?

TIA
-ashish

Ashish:
Page.RegisterHiddenField doesn't create a server side control, it just
creates a plain-old <input type="hidden">..so
Page.FindControl("myhiddenField") will never find anything....

If you call RegisterHiddenField twice with the same id, it'll only register
the field once, so:
Page.RegisterHiddenField("myhiddenfield", "hidden")
Page.RegisterHiddenField("myhiddenfield", "hidden")

there'll only be 1 myHiddenField

There's no way to tell which hidden fields have been registered this
way...on postback you can use Request.Form("myhiddenField") to get the
information though

You could always create a server control via:
dim myHiddenField as new HtmlInputHidden()
somePlaceHolder.Controls.Add(myHiddenField)


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!)


"ashish" <> wrote in message
news:...
> If i want to add a hidden field on the page, how can i check whether
> that hidden field exists ?
>
> for example if i do
>
> If Page.FindControl("myhiddenfield") Is Nothing Then
> Page.RegisterHiddenField("myhiddenfield", "hidden")
> End If
>
>
> Dim myHiddenField As HtmlInputHidden = Page.FindControl("myhiddenfield")
> ** this line would throw error
>
>
> how can i know that the hidden field is there before trying to add it ?
>
> TIA
> -ashish
>

If you register the same field twice with two different values, the first
value takes precedence.

Page.RegisterHiddenField( "myHiddenField", "value1" );
Page.RegisterHiddenField( "myHiddenField", "value2" );

"value1" will be rendered. The second call is ignored.

bill

"Karl Seguin" <karl REMOVE @ REMOVE openmymind REMOVEMETOO . ANDME net>
wrote in message news:...
> Ashish:
> Page.RegisterHiddenField doesn't create a server side control, it just
> creates a plain-old <input type="hidden">..so
> Page.FindControl("myhiddenField") will never find anything....
>
> If you call RegisterHiddenField twice with the same id, it'll only
register
> the field once, so:
> Page.RegisterHiddenField("myhiddenfield", "hidden")
> Page.RegisterHiddenField("myhiddenfield", "hidden")
>
> there'll only be 1 myHiddenField
>
> There's no way to tell which hidden fields have been registered this
> way...on postback you can use Request.Form("myhiddenField") to get the
> information though
>
> You could always create a server control via:
> dim myHiddenField as new HtmlInputHidden()
> somePlaceHolder.Controls.Add(myHiddenField)
>
>
> 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!)
>
>
> "ashish" <> wrote in message
> news:...
> > If i want to add a hidden field on the page, how can i check whether
> > that hidden field exists ?
> >
> > for example if i do
> >
> > If Page.FindControl("myhiddenfield") Is Nothing Then
> > Page.RegisterHiddenField("myhiddenfield", "hidden")
> > End If
> >
> >
> > Dim myHiddenField As HtmlInputHidden = Page.FindControl("myhiddenfield")
> > ** this line would throw error
> >
> >
> > how can i know that the hidden field is there before trying to add it ?
> >
> > TIA
> > -ashish
> >
>
>