File upload inside a usercontrol inside an updatepanel

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Leon Mayne - 23 May 2008 14:03 GMT

Having a bit of trouble here. I know that if you want to use a fileupload
control inside an AJAX update panel then you need to create a trigger for
the control that performs the uploading postback to the updatepanel, but the
problem is, I have an update panel inside a web usercontrol, and the
usercontrol is sitting inside an updatepanel on the host page. I therefore
can't add a trigger to the control directly, as the host page has no access
to the button within the usercontrol.

Does anyone know a way round this?

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bruce barker - 23 May 2008 16:47 GMT

as you don't want the fileupload to trigger a async postback (it needs to do
a browser postback to work), just be sure its not a trigger to the panel its
inside.

-- bruce (sqlwork.com)

> Having a bit of trouble here. I know that if you want to use a fileupload
> control inside an AJAX update panel then you need to create a trigger for
[quoted text clipped - 5 lines]
>
> Does anyone know a way round this?

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Leon Mayne - 27 May 2008 08:33 GMT

> as you don't want the fileupload to trigger a async postback (it needs to
> do
> a browser postback to work), just be sure its not a trigger to the panel
> its
> inside.

OK, do you know how to make just the file upload control not a trigger? The
rest of the controls in the usercontrol need to be triggers, but because
there is an extra layer between the update panel and the file upload control
I can't directly reference one from the other.

I guess I could make the control public, but wouldn't this get overwritten
as soon as the designer file is updated?

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Teemu Keiski - 23 May 2008 18:24 GMT

ScriptManager.RegisterPostBackControl does the equivalent in code (you get
reference to SM with ScriptManager.GetCurrent())

"Use the RegisterPostBackControl method to register postback controls inside
an UpdatePanel control as triggers. Controls that are registered by using
this method update a whole page instead of updating only the UpdatePanel
control's content. Registering a postback control with this method outside
an UpdatePanel control has no affect because by default these controls do
not perform asynchronous postbacks"

Signature

Teemu Keiski
AspInsider, ASP.NET MVP
http://blogs.aspadvice.com/joteke
http://teemukeiski.net

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Leon Mayne - 27 May 2008 08:30 GMT

> ScriptManager.RegisterPostBackControl does the equivalent in code (you get
> reference to SM with ScriptManager.GetCurrent())
[quoted text clipped - 5 lines]
> method outside an UpdatePanel control has no affect because by default
> these controls do not perform asynchronous postbacks"

Damn, almost worked, but it looks like neither the file upload control nor a
panel implement an appropriate interface:

"Control with ID 'pnlUpload' being registered through
RegisterAsyncPostBackControl or RegisterPostBackControl must implement
either INamingContainer, IPostBackDataHandler, or IPostBackEventHandler."

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Leon Mayne - 27 May 2008 10:02 GMT

>> ScriptManager.RegisterPostBackControl does the equivalent in code (you
>> get reference to SM with ScriptManager.GetCurrent())
[quoted text clipped - 12 lines]
> RegisterAsyncPostBackControl or RegisterPostBackControl must implement
> either INamingContainer, IPostBackDataHandler, or IPostBackEventHandler."

Oh wait, I registered the wrong control. I changed it to register the button
instead and it worked:

Dim scmCurrent As ScriptManager = ScriptManager.GetCurrent(Me.Page)
If scmCurrent IsNot Nothing Then
scmCurrent.RegisterPostBackControl(Me.btnUpload)
End If

Thanks Teemu.

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File upload inside a usercontrol inside an updatepanel

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