Running custom VbScript code from asp

Francesco Giossi — Mon, 27 Aug 2007 21:25:59 GMT

I was in the need to run some custom VbScript code from an asp page, so I went through the problem and found a very simple solution.
A common solution is to use the Microsoft ScriptControl.
Here is a very simple example running a piece of code stored in a text file.

default.asp

<%@language=VBSCRIPT%>
<%

dim sFile : sFile = ""

sFile = LoadFile("MyCustomScript.txt")

if len(sFile) > 0 then
    Response.Write "The result is: " & ExecScript(sFile)
end if

Function ExecScript(sScript)

        dim sc
        'Create the Script Control object
        set sc = server.CreateObject("scriptcontrol")

        sc.Language = "VBSCRIPT"
        sc.UseSafeSubset = false
        sc.Reset

        'add the custom script to the ScripContro object
        sc.AddCode sScript
        'run the code and evaluate the result of the "CustomScript" function
        ExecScript = sc.Eval("CustomScript")

        set sc = nothing

End Function

Function LoadFile(sFileName)
    Dim objFSO
    Set objFSO = Server.CreateObject("Scripting.FileSystemObject")

    Dim objTextStream
    dim strFileName
    dim lsTemp

    strFileName = server.MapPath(sFileName)
    const fsoForReading = 1

    If objFSO.FileExists(strFileName) then
        'The file exists, so open it and output its contents
        Set objTextStream = objFSO.OpenTextFile(strFileName, fsoForReading)
        lsTemp= vbNullString & objTextStream.ReadAll & vbNullString
        objTextStream.Close
        Set objTextStream = Nothing
    Else
        'The file did not exist
        Response.Write strFileName & " was not found."
    End If

    'Clean up
    Set objFSO = Nothing
    LoadFile = lsTemp
end function

%>

MyCustomScript.txt

function CustomScript()
    'Let's calculate the area of a rectangle
    dim dHeight : dHeight = 10
    dim dWidth : dWidth = 20
    CustomScript = cstr(dHeight * dWidth)
end function

This is a very easy example of how to use the Microsoft ScriptControl in an asp page.
A more realistic task would be, for example, store the script in a database, get the scripts from there and run 'em like exposed above.