PowerShell authenticate and read google calendar events - powershell

Question

Using PowerShell, I am trying to authenticate to Google calendar using a service account, and read events. With the help of stack overflow, I was able to install and import the required packages in my PowerShell session.
Newtonsoft.Json
Google.Apis.Core
Google.Apis
Google.Apis.Auth
Google.Apis.Calendar.v3
I then tried to read Google calendar events
# Set the credentials and calendar ID
$credentials = Get-Content "C:\Users\Windows\Desktop\powershell-376318-70973daa61d9.json" | ConvertFrom-Json
$calendarId = "primary"
# Build the calendar service
$service = New-Object Google.Apis.Calendar.v3.CalendarService
$service.Credentials = New-Object Google.Apis.Auth.OAuth2.GoogleCredential($credentials)
# Get the current time
$now = Get-Date
# Get the events for the next hour
$events = $service.Events.List($calendarId)
$events.TimeMin = $now
$events.TimeMax = $now.AddHours(1)
$events.SingleEvents = $true
$events.OrderBy = "startTime"
$events = $events.Execute()
# Print the events
foreach ($event in $events.Items) {
Write-Host "Event: $($event.Summary)"
Write-Host "Start Time: $($event.Start.DateTime)"
Write-Host "End Time: $($event.End.DateTime)"
Write-Host ""
}
But I get this error
New-Object : A constructor was not found. Cannot find an appropriate constructor for type
Google.Apis.Auth.OAuth2.GoogleCredential.
At line:7 char:24
+ ... edentials = New-Object Google.Apis.Auth.OAuth2.GoogleCredential($cred ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (:) [New-Object], PSArgumentException
+ FullyQualifiedErrorId : CannotFindAppropriateCtor,Microsoft.PowerShell.Commands.NewObjectCommand
Exception calling "Execute" with "0" argument(s): "The service calendar has thrown an exception. HttpStatusCode is
Forbidden. The request is missing a valid API key."
At line:18 char:1
+ $events = $events.Execute()
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : GoogleApiException
Obviously, there's an issue with "Google.Apis.Auth.OAuth2.GoogleCredential". I'm not sure it's even possible to authenticate and read events using a service account, but right now I don't know how to proceed with this.
I want to avoid using OAuth2 client id and client secret for authentication if possible, because I've had issues in the past with token expiries, whereas a service account doesn't expire.

Answer 1

The error message tells you exactly what the problem is:
Cannot find an appropriate constructor for type Google.Apis.Auth.OAuth2.GoogleCredential.
Having a look at the docs shows: There really is no constructor like GoogleCredential(string). But you can use different static methods to create a GoogleCredential object. E. g. FromJson(String):
# Set the credentials and calendar ID
$credentials = Get-Content -Raw -Path "C:\Users\Windows\Desktop\powershell-376318-70973daa61d9.json"
# Build the calendar service
$service = New-Object Google.Apis.Calendar.v3.CalendarService
$service.Credentials = [Google.Apis.Auth.OAuth2.GoogleCredential]::FromJson($credentials)
You can also pass the file directly to GoogleCredential via FromFile:
# Build the calendar service
$service = New-Object Google.Apis.Calendar.v3.CalendarService
$service.Credentials = [Google.Apis.Auth.OAuth2.GoogleCredential]::FromFile('C:\Users\Windows\Desktop\powershell-376318-70973daa61d9.json')