(Xojo Plugin) Automatically Refresh Token for 401 Unauthorized

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

Chilkat Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

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

// Get our current access token.
Dim jsonToken As New Chilkat.JsonObject
Dim success As Boolean
success = jsonToken.LoadFile(tokenFilePath)
If (jsonToken.HasMember("access_token") = False) Then
    System.DebugLog("No access token found.")
    Return
End If

Dim http As New Chilkat.Http
http.AuthToken = jsonToken.StringOf("access_token")

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

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

    // The access token must've expired. 
    // Refresh the access token and then retry the request.
    Dim oauth2 As New Chilkat.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
        System.DebugLog(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.
    success = jsonToken.UpdateString("access_token",oauth2.AccessToken)

    // Save the new JSON access token response to a file.
    Dim sbJson As New Chilkat.StringBuilder
    jsonToken.EmitCompact = False
    success = jsonToken.EmitSb(sbJson)
    success = sbJson.WriteFile(tokenFilePath,"utf-8",False)

    System.DebugLog("OAuth2 authorization granted!")
    System.DebugLog("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
        System.DebugLog(http.LastErrorText)
        Return
    End If

End If

System.DebugLog(jsonResponse)
System.DebugLog("-----------------------------")