Question
Is it possible to call Microsoft Graph API using VBA code?
If yes, how to handle O365 authorization? I have seen plenty of topics
So the code you show is only partially correct. Here is what I found to actually work. (This is with what you provided as I actually found a Json parser to work with the data better than the innerHTML methods, I also had to use a different version of MSXML since the one you reference wasnt working for me.)
Function GetToken()
Dim xml As New MSXML2.XMLHTTP60
Dim doc As MSHTML.HTMLDocument
Dim urltoken As String
'copy paste the URL you see when calling Microsoft Graph Explorer and add prompt + domain_hint parameters
urltoken = "https://login.microsoftonline.com/{tenent id}/oauth2/v2.0/token"
xml.Open "POST", urltoken, False
xml.Send("client_id={clientid}&scope=https://graph.microsoft.com/.default&grant_type=client_credentials&client_secret=(cleint secret}")
If xml.readyState = 4 And xml.Status = 200 Then
Set doc = New MSHTML.HTMLDocument
doc.Body.innerHTML = xml.responseText
GetToken = doc.getElementsByName("access_token")(0).Value
sSuccess = True
Else
MsgBox "Error" & vbNewLine & "Ready state: " & xml.readyState & _
vbNewLine & "HTTP request status: " & xml.Status
sSuccess = False
End If
Set xml = Nothing
End Function