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.Valu e before using Ctype function for converting the value into byte array. The value of Paramvalue.Valu e 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.NullRefe renceException: 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/sample_code/tech/windows/odpnet/howto/anonyblock/index.html

The Try and Catch returns:

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

[CroCrew]

Thanks, I have everything working now.