How to allow iPad user to use Fileupload? : The Official Microsoft ASP.NET Forums

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Condado

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How to allow iPad user to use Fileupload?

Feb 13, 2011 12:24 AM|LINK

I'm using an image field in the EditTemplate of FormView to allow my users to upload an image. It works fine in all major browsers, including Safari. But not on the iPad. There I get the error message "object reference not set to an instance of an object" when the EditTemplate is submitted.

I'm guessing it's because, on the iPad, the FileUpload button in my EditTemplate is "greyed out" (which is a problem in and of itself)...I suppose there's no built-in way for an iPad user (using the iPad version of Safari) to search for an image on the iPad hard drive to upload (without a special App, I'm guessing)....So, when the EditTemplate form is submitting on an iPad, I get the above error message---I think because the Fileupload field is Null (I have this theory, because the stack trace references my "ValidateImage" method in my code behind.)

Anybody have any direction or answers I should try? Is there an obvious answer here, or should I post my EditTemplate mark-up and code behind?

Thanks.

Condado

Moved by mbanavige on Feb 13, 2011 12:29 AM

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Mikesdotnett...

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Re: How to allow iPad user to use Fileupload?

Feb 13, 2011 02:06 PM|LINK

You should add a check in your code to see if the Uploaded File is null before trying to manipulate something that might not be there in any case. As far as the IPad is concerned, you can't upload and download files from or to it. File transfer is managed by dedicated apps.

Regards, Mike
Beginning ASP.NET Web Pages with WebMatrix | My Site | Twitter

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Condado

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Re: How to allow iPad user to use Fileupload?

Feb 13, 2011 07:46 PM|LINK

Sub ValidateImage(ByVal source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs)


        If Session("Image") = True Then
            ' There is a file
            Dim uploadAvatar As FileUpload = DirectCast(AdvertisementForm.FindControl("uploadAvatar"), FileUpload)
            Dim UploadFileName As String = uploadAvatar.PostedFile.FileName
            If UploadFileName = "" Then


                ' There is no file selected
                args.IsValid = True
            Else
                Dim Extension As String = UploadFileName.Substring(UploadFileName.LastIndexOf(".") + 1).ToLower()
                ' Valid file type
                If Extension = "jpg" Or Extension = "bmp" Then
                    args.IsValid = True
                Else
                    ' Not valid file type
                    args.IsValid = False
                End If
            End If
        Else
            Dim uploadAvatar As FileUpload = DirectCast(AdvertisementForm.FindControl("uploadAvatar"), FileUpload)
            Dim UploadFileName As String = uploadAvatar.PostedFile.FileName
            If UploadFileName = "" Then
                ' There is no file selected
                args.IsValid = False
            Else
                Dim Extension As String = UploadFileName.Substring(UploadFileName.LastIndexOf(".") + 1).ToLower()
                ' Valid file type
                If Extension = "jpg" Or Extension = "bmp" Then
                    args.IsValid = True
                Else
                    ' Not valid file type
                    args.IsValid = False
                End If
            End If
        End If
    End Sub

Thanks Mike...Above is I think the method that's causing the problem. I believe I've got a check there for when uploadAvatar is empty...Can you find anything amiss here or that I could add to improve it? Thanks.

Condado

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Mikesdotnett...

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Re: How to allow iPad user to use Fileupload?

Feb 13, 2011 08:26 PM|LINK

Condado
Dim UploadFileName As String = uploadAvatar.PostedFile.FileName

You are trying to reference a file here. If there is no file, the code will error because you cannot get a property (FileName) of an object that doesn't exist. You should use the Upload.HasFile property to check to see if anything was uploaded:

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.fileupload.hasfile.aspx

Regards, Mike
Beginning ASP.NET Web Pages with WebMatrix | My Site | Twitter