Does VBScript Support Introspection for Objects? - vbscript

Question

I am pulling results back from WMI using WQL via VBScript.
In examples, a For Each loop is used to iterate over the results, but in each example, it is assumed that the property names are known. Case in point:
Set colInstalledPrinters = objWMIService.ExecQuery ("Select * from Win32_Printer Where Default = True")
For Each objPrinter in colInstalledPrinters
Wscript.Echo objPrinter.Name
Next
Some of the WMI classes have a very long list of properties associated with them. As an additional complication, some properties cannot be expected to be present (according to various webpages I have read about WMI). Rather than researching each WMI class and hoping that the properties listed are present, I would like to obtain a list of the properties (or columns, if I am thinking in SQL/WQL) present for, say, an objPrinter or any other returned item.
Python is my usual language but I cannot install it on the target machines in this instance; I can perform remote querying of WMI via Python but I am trying to trigger on an local event, hence falling back to VBScript. Although I gather Powershell might be able to do this, I would rather not learn it just this instant.
So, does VBScript support that level of introspection which would allow me to enumerate a list of properties? Or is there something I can do involving a schema I can reference and examine in-script?

Answer 1

Use the .Properties_ collection of the item:
Option Explicit
Const wbemFlagReturnImmediately = &h10
Const wbemFlagForwardOnly = &h20
Dim objWMIService
Set objWMIService = GetObject("winmgmts:\\.\root\CIMV2")
Dim colItems
Set colItems = objWMIService.ExecQuery( _
"SELECT * FROM Win32_Printer" _
, "WQL" _
, wbemFlagReturnImmediately + wbemFlagForwardOnly _
)
Dim objItem
For Each objItem In colItems
Dim oProp
For Each oProp In objItem.Properties_
WScript.Echo oProp.Name, TypeName( oProp.Value ), ToString( oProp.Value )
Next
WScript.Echo
Next
Function ToString( vX )
ToString = "!! work to do !!"
On Error Resume Next
ToString = CStr( vX )
On Error GoTo 0
End Function
Output:
...
MimeTypesSupported Null !! work to do !!
Name String Auto HP LaserJet 5 on WINXP2
NaturalLanguagesSupported Null !! work to do !!
Network Boolean False
PaperSizesSupported Variant() !! work to do !!
...
Obviously, the ToString() function needs further work.