Google Calendar - To manage multiple users calendar - vb.net

Question

I have a module in my .NET system that manage multiple user's Google Calendar which written base on their V2 API that was depreciated few days ago.
My question is, how can I access and manage multiple users calendar? As in V2 API we can just pass in UserID and Password to access the resources. But in V3, OAuth2 is used. I manage to authenticate for one user at a time. How can I access the another user calendar after this? (eg:logut user1 and login with user2 again?). I can't find any relevant example so far.
Sub Main()
Dim secret As New ClientSecrets
secret.ClientId = "MyClientID.apps.googleusercontent.com"
secret.ClientSecret = "MyClientSecret"
Dim init As New Flows.AuthorizationCodeFlow.Initializer("https://accounts.google.com/o/oauth2/auth", "https://accounts.google.com/o/oauth2/token")
init.ClientSecrets = secret
Dim flow As New Flows.AuthorizationCodeFlow(init)
Dim token As Responses.TokenResponse = flow.LoadTokenAsync("user1#gmail.com", CancellationToken.None).Result
Dim credential As New UserCredential(flow, "user1#gmail.com", token)
Try
credential = GoogleWebAuthorizationBroker.AuthorizeAsync(secret, {CalendarService.Scope.Calendar}, "user", CancellationToken.None, New FileDataStore("CAS.GoogleConnector")).Result
Catch ex As Exception
MsgBox(ex.Message)
End Try
' Create the calendar service using an initializer instance
Dim initializer As New BaseClientService.Initializer()
initializer.HttpClientInitializer = credential
initializer.ApplicationName = "Clinic Assist"
Dim service As CalendarService
service = New CalendarService(initializer)
Dim a As CalendarsResource.GetRequest = service.Calendars.Get("user1#gmail.com")
a.Execute()
Console.WriteLine("Press any key to continue...")
Dim key As ConsoleKeyInfo = Console.ReadKey
If key.Key = ConsoleKey.N Then
NewEvent(service)
ElseIf key.Key = ConsoleKey.D Then
DeleteEvent(service)
ElseIf key.Key = ConsoleKey.C Then
NewCalendar(service)
End If
End Sub
Private Sub NewEvent(service As CalendarService)
Dim startDateTime, endDateTime As New Data.EventDateTime
startDateTime.DateTime = "2014-12-01T16:00:00"
endDateTime.DateTime = "2014-12-01T17:00:00"
Dim eventData As New Data.Event
With eventData
.Start = startDateTime
.End = endDateTime
.Location = "ALocation"
.Summary = "TRY"
End With
Try
Dim insertRequest As InsertRequest = service.Events.Insert(eventData, "user1#gmail.com")
insertRequest.Execute()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
I tried to change the userId from "user1#gmail.com" to "user2#gmail.com" it seems to have accessing the user1 calendar as well. Appreciate if anyone could help this out.

Answer 1

If all the users are on single domain you can use Service Accounts. Service account belongs to your application instead of to an individual end user. Your application calls Google APIs on behalf of the service account, so users aren't directly involved.
If users are not on the same domain, you will need to store credentials for each user in your application. Here is the link which helps you.