Blob

[CroCrew]

Hello Everyone,

I first want to start off with thanks to anyone that helps me out with this problem. With that said let me ask my question.

I am developing a .NET webpage using VB.NET. What I am trying to do with in this webpage is to query an Oracle database table that hold PDF documents in a BLOB container/field. After running my query I want to display the PDF from the query on the page. Below is what I have so far from trying to figure it out myself.

The error that I am currently getting is on line 28: Object reference not set to an instance of an object.

I have hit my wits end on this one. So, if anyone can help out I would be indebted to them.

Again, thanks

CroCrew~

Imports System.IO
Imports Oracle.DataAccess.Client
Imports Oracle.DataAccess.Types
 
Partial Class _Default
    Inherits System.Web.UI.Page
 
    Sub GetPDF(ByVal IdNumber As Integer)
        Dim con As OracleConnection = New OracleConnection("Data Source=MIB; User ID=web_view; Password=webview;")
        con.Open()
 
        Dim DestinationLoc As String = Server.MapPath("PDF") & "\" & "Data.pdf"
 
        Dim block As String = "SELECT PdfImage FROM PDF WHERE KeyId = " & IdNumber
        Dim cmd As OracleCommand = New OracleCommand()
        cmd.CommandText = block
        cmd.Connection = con
        cmd.CommandType = Data.CommandType.Text
 
        Dim param2 As OracleParameter = cmd.Parameters.Add("blobfromdb", OracleDbType.Blob)
        param2.Direction = Data.ParameterDirection.Output
 
        cmd.ExecuteNonQuery()
 
        Dim byteData As Byte()
        Dim Paramvalue As OracleBlob = cmd.Parameters(0).Value
 
        byteData = CType((Paramvalue.Value), Byte())
 
        Dim ArraySize As Integer = New Integer()
        ArraySize = byteData.GetUpperBound(0)
 
        Dim fs1 As FileStream = New FileStream(DestinationLoc, FileMode.OpenOrCreate, FileAccess.Write)
        fs1.Write(byteData, 0, ArraySize)
        fs1.Close()
 
        Response.Write("Done!")
    End Sub
 
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        GetPDF(23)
    End Sub
End Class
 

[shweta123]

Hi,

Please check for the value of Paramvalue.Value before using Ctype function for converting the value into byte array. The value of Paramvalue.Value might be Null. Also you can use try and catch in order to get the exception.

[CroCrew]

Sorry for not understand but, can you give me an example on what your asking me to do. Thanks~

[CroCrew]

The Try and Catch returns:

System.NullReferenceException: Object reference not set to an instance of an object.

[shweta123]

Hi,

Please refer to the following example to solve the error you are getting:

http://www.oracle.com/technology/sam...ock/index.html


@CroCrew

[CroCrew]

Thanks, I have everything working now.