Excel vba download file with random file extension - asp.net

Question

I am trying to write a code to automatically download files from a website by Excel vba. I know there are plenty of posts regarding this topic but no luck so far. The first few lines of code go like this:
Sub testing()
Dim ie as object
Url _base = "http://www..../download.aspx?id="
Num = cells(1,1).value
Set ie = createobject ("internetexplorer.application")
Ie.visible = true
For i = 1 to num
Url = url _base & i
....
Then I become clueless. The problem is that winhttp seems to only download csv files, and urldownloadtofile requires a solid url path ending with the file extension. However, my case is the link is redirecting to the actual file location (no extension shown), and also the file could be any extension such as pdf, jpg, and doc.
Thanks all in advance!

Answer 1

Ok, editing answer to fold in feedback, three different ways to make an HTTP request and it seems you are looking to trap a redirect which is status codes 300-303, 307-308. Try this and provide feedback as to whether or not you are redirected.
Option Explicit
Private Sub TestGetFileFromWeb()
Call SaveTextToFile(GetFileFromWeb2("http://www.wikipedia.com"), "c:\temp\wikipedia2.txt")
Call SaveTextToFile(GetFileFromWeb3("http://www.wikipedia.com"), "c:\temp\wikipedia3.txt")
'* placed last because it gives "Access Denied" Run-time error '-2147024891 &h80070005
'Call SaveTextToFile(GetFileFromWeb1("http://www.wikipedia.com"), "c:\temp\wikipedia1.txt")
Call SaveTextToFile(GetFileFromWeb1("http://www.bbc.com"), "c:\temp\bbc.txt")
End Sub
Private Function SaveTextToFile(ByRef sText As String, ByVal sFileName As String) As Boolean
'* Requires Tools ->References -> Microsoft Scripting Runtime
Dim fso As Scripting.FileSystemObject
Set fso = New Scripting.FileSystemObject
Dim txtOut As Scripting.TextStream
Set txtOut = fso.CreateTextFile(sFileName, , True)
txtOut.Write sText
txtOut.Close
Set txtOut = Nothing
Set fso = Nothing
SaveTextToFile = True
End Function
Private Function GetFileFromWeb1(ByVal sURL As String) As String
'* Requires Tools->References->Microsoft Xml, v.6.0
Dim xHTTPRequest As MSXML2.XMLHTTP60
Set xHTTPRequest = New MSXML2.XMLHTTP60
xHTTPRequest.Open "GET", sURL, False
xHTTPRequest.Send
Debug.Assert WasRedirected(xHTTPRequest.Status)
GetFileFromWeb1 = xHTTPRequest.ResponseText
End Function
Private Function GetFileFromWeb2(ByVal sURL As String) As String
'* Requires Tools->References->Microsoft WinHTTP Services, version 5.1
Dim oWinHttp As WinHttp.WinHttpRequest
Set oWinHttp = New WinHttp.WinHttpRequest
oWinHttp.Open "GET", sURL, False
oWinHttp.Send
Debug.Assert WasRedirected(oWinHttp.Status)
GetFileFromWeb2 = oWinHttp.ResponseText
End Function
Private Function WasRedirected(ByVal lStatus As Long) As Boolean
'http://qnimate.com/redirection-and-duplicate-content-in-websites/
'There are many types of HTTP redirection.
'
'300 Redirect or Multiple Choices
'301 Redirect or permanent redirect
'302 Redirect or Found or Temporary Redirect
'303 Redirect or See Other
'307 Redirect or Temporary Redirect
'308 Redirect or Permanent Redirect
'HTTP refresh header
WasRedirected = (lStatus = 300 Or lStatus = 301 Or lStatus = 302 Or lStatus = 303 Or lStatus = 307 Or lStatus = 308)
End Function
Private Function GetFileFromWeb3(ByVal sURL As String) As String
'* Requires Tools->References->Microsoft Xml, v.6.0
Dim xHTTPRequest As MSXML2.ServerXMLHTTP60
Set xHTTPRequest = New MSXML2.ServerXMLHTTP60
xHTTPRequest.Open "GET", sURL, False
xHTTPRequest.Send
Debug.Assert WasRedirected(xHTTPRequest.Status)
GetFileFromWeb3 = xHTTPRequest.ResponseText
End Function