asked on

ASP.net VB.net check if a file is a valid pdf

Hi

In ASP.net what code would I use to check if a certain file is a pdf. I want to add this check to the following code

    Protected Sub btnView_Click(sender As Object, e As EventArgs) Handles btnView.Click
        Try
            Dim oSelectedFile As String
            If Me.ListBox1.SelectedItem.Text <> "" Then
                oSelectedFile = Me.ListBox1.SelectedItem.Text
            Else
                Exit Sub
            End If
            'Response.Clear()
            'Dim filePath As String = "~/Uploads/" & oSelectedFile
            'Response.ContentType = "application/pdf"
            'Response.WriteFile(filePath)
            'Response.TransmitFile(filePath)

            'Dim FilePath As String = Server.MapPath("piyushsir.pdf")
            Dim FilePath As String = Server.MapPath("~/Uploads/" & oSelectedFile)
            Dim User As New System.Net.WebClient()
            Dim FileBuffer As [Byte]() = User.DownloadData(FilePath)
            If FileBuffer IsNot Nothing Then
                Response.ContentType = "application/pdf"
                Response.AddHeader("content-length", FileBuffer.Length.ToString())
                Response.BinaryWrite(FileBuffer)
            End If

        Catch ex As Exception
            'Response.Write(ex.Message)
            Me.lblErrorDeleting.Text = ex.Message & " hr556"
        End Try
    End Sub

Open in new window

ASKER CERTIFIED SOLUTION

Norie

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

SOLUTION

Rikin Shah

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

Murray Brown

ASKER

Thanks

Chinmay Patel

Hi Murray,

I am not sure how this happened but I put in 3 possible ways to solve this. Somehow that comment never made it.
1. Check file extension and see if it is pdf or not. - Easiest but not reliable.
2. Read header bytes and figure out if the file is a PDF or an image - might not be as accurate as other methods.
3. Check if it is pdf using any PDF library and if it is not, check if it is a valid image and proceed accordingly - Hardest but most accurate.

Hope this helps.

Regards,
Chinmay.

Murray Brown

ASKER

Thanks. I still don't know how to best view the image. Should I use an image control and just set the Image ImageUrl to this or is there a better way?

SOLUTION

Chinmay Patel

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial