How can I use Session variable in an HttpHandler

Question

Goal: I have a thumbnail as a byte array in memory. Once a user uploads their image, I want to display it in an httphandler before writing it to the database. I have used this code to successfully read it and display from a database. But now I want to display it from the session:

Public Sub ProcessRequest(ByVal context As HttpContext) _
    Implements IHttpHandler.ProcessRequest

    Dim oPhotoMgt As New PhotoMgt
    Dim intPhotoID As Int32 = context.Request.QueryString("id") 
    Dim oPhoto As New Photo
    oPhoto = oPhotoMgt.GetPhotoByID(intPhotoID)   

    context.Response.ContentType = "image/jpeg" 
    context.Response.BinaryWrite(oPhoto.Bytes.ToArray())
End Sub

Answer 1

You should mark your class with the IRequiresSessionState interface (System.Web.SessionState namespace). It has no methods or properties, so you shouldn't have to change anything else about your code.

The signature would be:

Imports System.Web
Imports System.Web.SessionState

Public Class MyHandler
    Implements IHttpHandler, IRequiresSessionState

    Public Sub ProcessRequest(ByVal context As HttpContext) _
        Implements IHttpHandler.ProcessRequest

        context.Session("foo") = "bar"
    End Sub
End Class

Answer 2

Thorarin was correct. I had to implement IRequiresSessionState. What I didn't realize was that I then had to refer to the variable as

context.Session("oUser")

instead of

Session("oUser")