How can we make this code run with option strict on? - vb.net

Question

Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
lblSystemSerialNumbers.Text = SystemSerialNumber()
lblCpuIds.Text = CpuId()
End Sub
Private Function SystemSerialNumber() As String
' Get the Windows Management Instrumentation object.
Dim wmi As Object = GetObject("WinMgmts:")
' Get the "base boards" (mother boards).
Dim serial_numbers As String = ""
Dim mother_boards As Object = wmi.InstancesOf("Win32_BaseBoard")
For Each board As Object In mother_boards
serial_numbers &= ", " & board.SerialNumber
Next board
If serial_numbers.Length > 0 Then serial_numbers = serial_numbers.Substring(2)
Return serial_numbers
End Function
Private Function CpuId() As String
Dim computer As String = "."
Dim wmi As Object = GetObject("winmgmts:" & _
"{impersonationLevel=impersonate}!\\" & _
computer & "\root\cimv2")
Dim processors As Object = wmi.ExecQuery("Select * from Win32_Processor")
Dim cpu_ids As String = ""
For Each cpu As Object In processors
cpu_ids = cpu_ids & ", " & cpu.ProcessorId
Next cpu
If cpu_ids.Length > 0 Then cpu_ids = cpu_ids.Substring(2)
Return cpu_ids
End Function
End Class
This code will retrieve the CPU id and the motherboard id. How do I ensure that this will work even when option strict is on.
Why this could be a problem?
Well, let's see. The type of wmi is Object. That wmi do not necessarily support methods like InstancesOf, and SerialNumber
So how can we pull this out?
I think object that we got from GetObject is not just pure object. I think we should ctype or direct cast it to a more appropriate type. That more appropriate type will support methods like InstancesOf, SerialNumber, etc.
However what are the appropriate types?

Answer 1

You could use the ManagementObjectSearcher from the WMI classes hosted inside the System.Management.dll assembly.
(And you need to add the appropriate reference).
In this way you could write the SystemSerialNumber as
Private Function SystemSerialNumber(computer As String) As String
Dim wmi = New ManagementObjectSearcher(computer & "\root\cimv2", "select * from Win32_BaseBoard")
Dim boards = New List(Of String)()
For Each board In wmi.Get()
Dim temp = board.Properties("SerialNumber").Value?.ToString()
If Not String.IsNullOrEmpty(temp) Then
boards.Add(temp)
End If
Next board
Return String.Join(", ", boards)
End Function
The CpuId function is a bit more complex because you want to set the Impersonate flags but it is still possible to write a method around the NET wrapper classes for WMI interfaces
Private Function CpuId(computer As String) As String
Dim cpu = New List(Of String)()
Dim options = New ConnectionOptions()
options.Impersonation = System.Management.ImpersonationLevel.Impersonate
Dim scope = New ManagementScope(computer & "\root\cimv2", options)
scope.Connect()
Dim query = New ObjectQuery("Select * from Win32_Processor")
Dim wmi = New ManagementObjectSearcher(scope, query)
For Each m As ManagementObject In wmi.Get()
Dim temp = m.Properties("ProcessorId").Value?.ToString()
If Not String.IsNullOrEmpty(temp) Then
cpu.Add(temp)
End If
Next
Return String.Join(", ", cpu)
End Function