Show image using function - mysql

Question

I'm new to VB. NET so please bear with me. In the code below, I have a picture box in my main form and I want the selected query profile_picture to show in the picture box but I have no idea what the function should return
Public Sub ShowPicture(ByVal username As String)
user = username
Dim dsSearch As DataSet
ModuleQuery.Showpic(username)
Dim dSearch As Byte() = DirectCast(dr("Photo"), Byte())
Dim ms As New MemoryStream(dsSearch)
prof_pic.Image = Image.FromStream(ms)
End Sub
This is a module which includes all SELECT queries so that it won't be messy.
I want to call a function but I don't know what to return so that I can show the image
Public Function Showpic(ByVal user As String)
Dim FunctionErrorState As Boolean = False
Dim InsertError As Boolean = False
Dim CloseError As Boolean = False
Dim dsData As New DataSet
Dim bite As Byte()
Try
openDB()
'MyADOConnection.Open()
Dim myQuery As String = "SELECT profile_picture FROM coa.register WHERE username = '" & user & "'"
Dim myCommand As New MySql.Data.MySqlClient.MySqlCommand(myQuery)
dr = myCommand.ExecuteReader
bite = DirectCast(dr("Photo"), Byte())
Catch ex As MySql.Data.MySqlClient.MySqlException
InsertError = True
End Try
Try
MyADOConnection.Close()
Catch exclose As MySql.Data.MySqlClient.MySqlException
CloseError = True
End Try
If InsertError Then
FunctionErrorState = True
End If
Return bite 'I just put something random here since I don't know what to retun
End Function

Answer 1

It looks to me like the image is being stored as a byte array in the database. You (i guess correctly) read this array from the database with the command bite = DirectCast(dr("Photo"), Byte()) in your ShowPic function. A byte array is just a large blob of data in memory, that you later query with the MemoryStream.
Therefore your ShowPic function (which is more a GetPic function ;-) should return Byte()
Public Function Showpic(ByVal user As String) As Byte()
You should initialize bite with Nothing
Dim bite As Byte() = Nothing
That way if an error occurs, the array will be nothing and you can check for that.
In order to convert the byte array, that contains the raw image data into an image you correctly use a MemoryStream and the Image.FromStream method. I/O in .NET works in large portions with streams. They are just a way to continously feed data from some source. In this case the source is just the memory, in particular the Byte array you got from the database.
You however never use that Byte array. Assign the result of the ShowPic function to a variable, in order to use it:
Public Sub ShowPicture(ByVal username As String)
user = username
Dim ImageData As Byte() = ModuleQuery.Showpic(username)
If ImageData IsNot Nothing Then
Using ms As New MemoryStream(ImageData)
prof_pic.Image = Image.FromStream(ms)
End Using
Else
'Your function returned nothing, so an error occured.
'This is a very crude way of error handling, since you never
'see the error in the first place, which makes debugging a
'nightmare. There are better ways, out of scope of this answer.
MessageBox.Show("No image retrieved due to an error :(")
End If
End Sub
That way you retrieve the image data from the database (again, rename it to GetPic or GetImageData or something) in ShowPic and return its raw data to the ShowPicture method where you decode and show it.