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Linq to sql - Don't understand why I get error from example

Posted on 2010-11-14
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Last Modified: 2013-11-12
I have only been playing with asp.net and linq for about a year and am trying to create a picture portfolio.
I found an example on the web, but am having a problem understanding the function provided.
In the sample app, they receive no error, but in my environment, I recieve an error
value of type system.data.linq.binary cannot be converted to 1 - dimensional array of byte.
The fields in the db are of type image.
Would someone please explain to me what this is doing and why I am getting the error when it table is set up like it.
Thanks

Private Shared Function GetPhotoBytes(ByVal source As IQueryable(Of Portfolio), ByVal size As PhotoSize) As Stream
        Dim imageBytes As Byte()

        Select Case size
            Case PhotoSize.Large
                imageBytes = source.Select(Function(p) p.BeforePicBytesFull).SingleOrDefault
            Case PhotoSize.Original
                imageBytes = source.Select(Function(p) p.BytesOriginal).SingleOrDefault
            Case PhotoSize.Small
                imageBytes = source.Select(Function(p) p.BytesThumb).SingleOrDefault
            Case Else
                imageBytes = source.Select(Function(p) p.BytesPoster).SingleOrDefault
        End Select
        If imageBytes IsNot Nothing Then
            Return New MemoryStream(imageBytes)
        Else
            Return New MemoryStream()
        End If
    End Function

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Question by:Sheritlw
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3 Comments
 
LVL 75

Accepted Solution

by:
käµfm³d   👽 earned 2000 total points
ID: 34133548
Select() is a transforming function. In other words, you take one type of object and convert it to another type. Your code is trying to assign a type of System.Data.Linq.Binary to an object of type Byte(). You may try calling the ToArray() method on your objects in your Selects:
Private Shared Function GetPhotoBytes(ByVal source As IQueryable(Of Portfolio), ByVal size As PhotoSize) As Stream
        Dim imageBytes As Byte()

        Select Case size
            Case PhotoSize.Large
                imageBytes = source.Select(Function(p) p.BeforePicBytesFull.ToArray()).SingleOrDefault
            Case PhotoSize.Original
                imageBytes = source.Select(Function(p) p.BytesOriginal.ToArray()).SingleOrDefault
            Case PhotoSize.Small
                imageBytes = source.Select(Function(p) p.BytesThumb.ToArray()).SingleOrDefault
            Case Else
                imageBytes = source.Select(Function(p) p.BytesPoster.ToArray()).SingleOrDefault
        End Select
        If imageBytes IsNot Nothing Then
            Return New MemoryStream(imageBytes)
        Else
            Return New MemoryStream()
        End If
    End Function

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Author Comment

by:Sheritlw
ID: 34133625
That seems to have worked.
Thank you
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LVL 75

Expert Comment

by:käµfm³d 👽
ID: 34133702
Sure thing. Glad to help  :)
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