Access sessions in asp.net handler - asp.net

Question

I am trying to upload images using generic handler as shown below and I have a normal aspx page where I am showing all the uploaded images after uploading.Everything is working fine.
<%# WebHandler Language="VB" Class="Upload"%>
Imports System
Imports System.Web
Imports System.Threading
Imports System.Web.Script.Serialization
Imports System.IO
Public Class Upload : Implements IHttpHandler, System.Web.SessionState.IRequiresSessionState
Public Class FilesStatus
Public Property thumbnail_url() As String
Public Property name() As String
Public Property url() As String
Public Property size() As Integer
Public Property type() As String
Public Property delete_url() As String
Public Property delete_type() As String
Public Property [error]() As String
Public Property progress() As String
End Class
Private ReadOnly js As New JavaScriptSerializer()
Private ingestPath As String
Public Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
Dim r = context.Response
ingestPath = context.Server.MapPath("~/UploadedImages/")
r.AddHeader("Pragma", "no-cache")
r.AddHeader("Cache-Control", "private, no-cache")
HandleMethod(context)
End Sub
Private Sub HandleMethod(ByVal context As HttpContext)
Select Case context.Request.HttpMethod
Case "HEAD", "GET"
ServeFile(context)
Case "POST"
UploadFile(context)
Case "DELETE"
DeleteFile(context)
Case Else
context.Response.ClearHeaders()
context.Response.StatusCode = 405
End Select
End Sub
Private Sub DeleteFile(ByVal context As HttpContext)
Dim filePath = ingestPath & context.Request("f")
If File.Exists(filePath) Then
File.Delete(filePath)
End If
End Sub
Private Sub ServeFile(ByVal context As HttpContext)
If String.IsNullOrEmpty(context.Request("f")) Then
ListCurrentFiles(context)
Else
DeliverFile(context)
End If
End Sub
Private Sub UploadFile(ByVal context As HttpContext)
Dim statuses = New List(Of FilesStatus)()
Dim headers = context.Request.Headers
If String.IsNullOrEmpty(headers("X-File-Name")) Then
UploadWholeFile(context, statuses)
Else
UploadPartialFile(headers("X-File-Name"), context, statuses)
End If
WriteJsonIframeSafe(context, statuses)
End Sub
Private Sub UploadPartialFile(ByVal fileName As String, ByVal context As HttpContext, ByVal statuses As List(Of FilesStatus))
If context.Request.Files.Count <> 1 Then
Throw New HttpRequestValidationException("Attempt to upload chunked file containing more than one fragment per request")
End If
Dim inputStream = context.Request.Files(0).InputStream
Dim fullName = ingestPath & Path.GetFileName(fileName)
Using fs = New FileStream(fullName, FileMode.Append, FileAccess.Write)
Dim buffer = New Byte(1023) {}
Dim l = inputStream.Read(buffer, 0, 1024)
Do While l > 0
fs.Write(buffer, 0, l)
l = inputStream.Read(buffer, 0, 1024)
Loop
fs.Flush()
fs.Close()
End Using
statuses.Add(New FilesStatus With {.thumbnail_url = "Thumbnail.ashx?f=" & fileName, .url = "Upload.ashx?f=" & fileName, .name = fileName, .size = CInt((New FileInfo(fullName)).Length), .type = "image/png", .delete_url = "Upload.ashx?f=" & fileName, .delete_type = "DELETE", .progress = "1.0"})
End Sub
Private Sub UploadWholeFile(ByVal context As HttpContext, ByVal statuses As List(Of FilesStatus))
For i As Integer = 0 To context.Request.Files.Count - 1
Dim file = context.Request.Files(i)
file.SaveAs(ingestPath & Path.GetFileName(file.FileName))
Thread.Sleep(1000)
Dim fname = Path.GetFileName(file.FileName)
statuses.Add(New FilesStatus With {.thumbnail_url = "Thumbnail.ashx?f=" & fname, .url = "Upload.ashx?f=" & fname, .name = fname, .size = file.ContentLength, .type = "image/png", .delete_url = "Upload.ashx?f=" & fname, .delete_type = "DELETE", .progress = "1.0"})
Next i
End Sub
Private Sub WriteJsonIframeSafe(ByVal context As HttpContext, ByVal statuses As List(Of FilesStatus))
context.Response.AddHeader("Vary", "Accept")
Try
If context.Request("HTTP_ACCEPT").Contains("application/json") Then
context.Response.ContentType = "application/json"
Else
context.Response.ContentType = "text/plain"
End If
Catch
context.Response.ContentType = "text/plain"
End Try
Dim jsonObj = js.Serialize(statuses.ToArray())
context.Response.Write(jsonObj)
End Sub
Private Sub DeliverFile(ByVal context As HttpContext)
Dim filePath = ingestPath & context.Request("f")
If File.Exists(filePath) Then
context.Response.ContentType = "application/octet-stream"
context.Response.WriteFile(filePath)
context.Response.AddHeader("Content-Disposition", "attachment, filename=""" & context.Request("f") & """")
Else
context.Response.StatusCode = 404
End If
End Sub
Private Sub ListCurrentFiles(ByVal context As HttpContext)
Dim files = New List(Of FilesStatus)()
Dim names = Directory.GetFiles(context.Server.MapPath("~/UploadedImages/"), "*", SearchOption.TopDirectoryOnly)
For Each name In names
Dim f = New FileInfo(name)
files.Add(New FilesStatus With {.thumbnail_url = "Thumbnail.ashx?f=" & f.Name, .url = "Upload.ashx?f=" & f.Name, .name = f.Name, .size = CInt(f.Length), .type = "image/png", .delete_url = "Upload.ashx?f=" & f.Name, .delete_type = "DELETE"})
Next name
context.Response.AddHeader("Content-Disposition", "inline, filename=""files.json""")
Dim jsonObj = js.Serialize(files.ToArray())
context.Response.Write(jsonObj)
context.Response.ContentType = "application/json"
End Sub
Public ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
Get
Return False
End Get
End Property
End Class
Now I want to add a session variable by generating a random string and add the uploaded images to the newly created random string.
1.I have seen this Question on SO to use System.Web.SessionState.IRequiresSessionState for sessions and how do I create a folder with that and add my images to that folder after doing that how do I access this session variable in my normal aspx page.
2.(Or) the better way is create session variable in aspx page and pass that to handler?If so how can I do that?
3 .I am trying to find the control from my handler.Is that possible?If anyone knows how to get this then also my problem will get resolved so that I am trying to create a session from m aspx page.
Can anyone explain the better way of handling this situation.

Answer 1

I completely agree with jbl's comment.
You can get and set session using HttpContext.Current.Session anywhere on your project.
No matter where you create the session. Just make sure that the session exists before you access it.
Not sure what exactly you are asking here(need some more explanation).
Here is an example, where I used session on HttpHandler. However, it is on c#(hope you can understand).

Answer 2

This is not really an answer but #Knvn wrote a C# example which I couldn't understand so I used a converter to convert it to VB. Posted it here in case it helps someone in the future.
Public Class HttpHandler
Implements IHttpHandler
Implements IRequiresSessionState
Public Sub New()
End Sub
Public Sub ProcessRequest(context As HttpContext)
Dim Request As HttpRequest = context.Request
Dim Response As HttpResponse = context.Response
If SessionHandler.Current.UserID = 0 Then
Response.Redirect("~/Default.aspx")
Else
Try
If Request.Path.EndsWith(".pdf") Then
Dim client As New WebClient()
Dim buffer As [Byte]() = client.DownloadData(HttpContext.Current.Server.MapPath(Request.Path))
Response.ContentType = "application/pdf"
Response.AddHeader("content-length", buffer.Length.ToString())
Response.BinaryWrite(buffer)
Else
Using reader As New StreamReader(HttpContext.Current.Server.MapPath(Request.Path))
Response.Write(reader.ReadToEnd())
End Using
End If
Catch
Response.Redirect("~/Default.aspx")
End Try
End If
End Sub
Public ReadOnly Property IsReusable() As Boolean
' To enable pooling, return true here.
' This keeps the handler in memory.
Get
Return False
End Get
End Property
End Class