Display saved PDF file from database to PDFVIEWER - mysql

Question

I have successfully saved a pdf file to my database (MySQL) as a longblob and used this code :
opf.Filter = "PDF FILES |*.pdf"
If opf.ShowDialog = Windows.Forms.DialogResult.OK Then
//Display the PDF you want to save in the PDFVIEWER
pdfview.src = opf.FileName
Dim Mystream As New FileStream(opf.FileName, FileMode.Open)
Dim filesize As Long = Mystream.Length
Dim buffer(filesize) As Byte
Mystream.Read(buffer, 0, filesize)
//Save the pdf file to the database
Dim query As String = "insert into sample(pdfnaho)values(#file)"
Dim cmd As New MySqlCommand(query, con)
con.Open()
cmd.Parameters.AddWithValue("#file", buffer)
cmd.ExecuteNonQuery()
MsgBox("SAVED!")
con.Close()
End If
Then I used this code for displaying but It doesn't work and I don't know what to do :
Dim query As String = "select * from sample where id = 1"
Dim cmd As New MySqlCommand(query, con)
con.Open()
Dim dr As MySqlDataReader = cmd.ExecuteReader
While dr.Read
If dr.HasRows Then
pdfview.src = dr.GetString("pdfnaho")
End If
End While
con.Close()
How should I display my saved pdf file from database? Thank You

Answer 1

I can not put this as a comment because I don't have enough reputation.
What PDF viewer are you using?. If it is the Adobe PDF Viewer I am almost sure (from previous research for another project) that you can not stream into it.
This is an example from my previous project, I modified it to fit yours, make sure to edit the query to fit your table and columns names.
You have to ran a query that return only the cell with the file in binary.
Dim query as String = "SELECT file_content FROM sample WHERE ID=1;"
Public Sub OpenPDF()
If File.Exists(Application.StartupPath() & "\temp.file") = True Then
pdfview.src = "blank.pdf"
My.Computer.FileSystem.DeleteFile(Application.StartupPath() & "\temp.file")
End If
Dim cmd As New MySqlCommand(query, con)
Dim Buffer As Byte()
con.open()
Buffer = cmd.ExecuteScalar
con.close()
File.WriteAllBytes(Application.StartupPath() & "\temp.file", Buffer)
pdfview.src = Application.StartupPath() & "\temp.file"
End Sub
With this example, the code will check if there is an existing "temp.file" and delete it, then load nothing on the pdfviewer to clear whatever is displaying.
The the database connection, get the data, store it on a file then display it with the pdfviewer.