using streamreader[resolved]

[mindloop]

hi there,
I've got an image stored in a database as type OLEobject.
What i don't know is how to read this using streamreader and use as Image object in vb.net.
Anyone ?
thanks

[jkothia]

Try the following. It might work for you. I am having problem using it for accessing data from Access database's memo field using oledb.

http://www.edneeis.com/tutorial.aspx?ID=7

This is from a similar quest of mine in a separate thread and provided by user edneeis.

[mindloop]

thanks for your reply,
but, well the problem is still there. i spent some hours just to get where edneeis has got before me, basically i kinda got to the same code. but it never stops throwing exceptions and i'm kinda tired . here is my code:

Public Function readimage(ByVal idfirma As Integer) As Image
        Dim img As Image
        Dim ImageByte As Byte()
        OleDbConnection1.Open() 
        ComandaSQL.CommandText = "select logo from firme where idfirma =" & idfirma  'comandasql is defined  as oledbcommand
        ImageByte = ComandaSQL.ExecuteScalar()
        OleDbConnection1.Close()
        Try
            Dim streamx As New MemoryStream()
            streamx.Write(ImageByte, 0, ImageByte.GetUpperBound(0))
            img = Image.FromStream(streamx)
            streamx.Close()
        Catch ex As Exception
            callMsg(ex.ToString) 'callMsg is my custom MsgBox
        End Try
        Return img
    End Function

without try...catch...end try the program stops at
img = image.fromstream(streamx)
throwing this exception:
"An unhandled exception of type 'System.ArgumentException' occurred in system.drawing.dll
Additional information: Invalid parameter used."

i compared the code with edneis'es code iand it's basically the same, just i use connection to db instead of datarow.
when pausing and placing cursor over imagebyte a tooltip shows me something like length={27569} , wich suggests the image was read.

for writing the image into database i use this code:

Private Sub SaveImage(ByVal imageX As Image, ByVal idfirma As Integer)
        Dim ImageStream As New MemoryStream()
        imageX.Save(ImageStream, imageX.RawFormat)
        Dim FileByteArray(CInt(ImageStream.Length)) As Byte
        ImageStream.Read(FileByteArray, 0, CInt(ImageStream.Length))
        Try
            OleDbConnection1.Open()
            ComandaSQL.CommandText = "update firme set logo=  ? where idfirma =" & idfirma.tostring
            ComandaSQL.Parameters.Add("Logo", System.Data.OleDb.OleDbType.Binary, CInt(ImageStream.Length)).Value = FileByteArray
            ComandaSQL.ExecuteNonQuery()
            OleDbConnection1.Close()
        Catch ex As Exception
            callMsg(ex.ToString)
        End Try
        ImageStream.Close()
    End Sub

[jkothia]

I am afraid I can't help you much here. I used similar method, only going the db->bytes and get invalid cast error when reading from database.

I am going to experiment a little, don't know when.

Another option is customizing the image file:
image->memorstream->byte()-> string via stringbuilder->db.
and on the way out from db
db->string->stringbuilder->byte()->image.

I've made it work for image->string->image. If I can make it work for the entire route, I'll post it here.

Good luck.

[mindloop]

thanks i'll keep an eye on this thread.
if i get there first i'll post too.

[jkothia]

Using a memo field instead of OLE Object in Access Database was my problem. May be that's true in your case too. Check out the related thread.

http://www.vbforums.com/showthread.php?s=&postid=1659002#post1659002

[mindloop]

i managed to solve this issue by saving the image to a temp file on hdd then using filestream to read the file
i was using from the begining oleobject
it works fine now for me

if you like i'l share the code just post and say so.