B4X

Automatically Refresh Token for 401 Unauthorized

See more Google Calendar Examples

Demonstrates how to automatically refresh an access token (without user interaction) when the token expires and a 401 Unauthorized response is received. B4X

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim tokenFilePath As String = "qa_data/tokens/googleCalendar.json"

'  Get our current access token.
Dim jsonToken As ChilkatJsonObject
jsonToken.Initialize
success = jsonToken.LoadFile(tokenFilePath)
If jsonToken.HasMember("access_token") = False Then
    Log("No access token found.")
    Return
End If

Dim http As ChilkatHttp
http.Initialize("http")
http.AuthToken = jsonToken.StringOf("access_token")

Dim jsonResponse As String = http.QuickGetStr("https://www.googleapis.com/calendar/v3/users/me/calendarList")
If http.LastMethodSuccess <> True Then

    If http.LastStatus <> 401 Then
        Log(http.LastErrorText)
        Log("----")
        Log(http.LastResponseBody)
        Return
    End If


    '  The access token must've expired. 
    '  Refresh the access token and then retry the request.
    Dim oauth2 As ChilkatOAuth2
    oauth2.Initialize("oauth2")

    oauth2.TokenEndpoint = "https://www.googleapis.com/oauth2/v4/token"

    '  Replace these with actual values.
    oauth2.ClientId = "GOOGLE-CLIENT-ID"
    oauth2.ClientSecret = "GOOGLE-CLIENT-SECRET"

    '  Get the "refresh_token"
    oauth2.RefreshToken = jsonToken.StringOf("refresh_token")

    '  Send the HTTP POST to refresh the access token..
    success = oauth2.RefreshAccessToken
    If success <> True Then
        Log(oauth2.LastErrorText)
        Return
    End If


    '  The response contains a new access token, but we must keep
    '  our existing refresh token for when we need to refresh again in the future.
    jsonToken.UpdateString("access_token", oauth2.AccessToken)

    '  Save the new JSON access token response to a file.
    Dim sbJson As ChilkatStringBuilder
    sbJson.Initialize
    jsonToken.EmitCompact = False
    jsonToken.EmitSb(sbJson)
    sbJson.WriteFile(tokenFilePath, "utf-8", False)

    Log("OAuth2 authorization granted!")
    Log("New Access Token = " & oauth2.AccessToken)

    '  re-try the original request.
    http.AuthToken = oauth2.AccessToken
    jsonResponse = http.QuickGetStr("https://www.googleapis.com/calendar/v3/users/me/calendarList")
    If http.LastMethodSuccess <> True Then
        Log(http.LastErrorText)
        Return
    End If

End If


Log(jsonResponse)
Log("-----------------------------")