(Visual FoxPro) Google Drive Refresh Access Token

Demonstrates how to automatically refresh the access token when it expires.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL loJson
LOCAL lcTokenFilePath
LOCAL loOauth2
LOCAL loFac

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

lnSuccess = 1

* This example uses a previously obtained access token having permission for the 
* Google Drive scope.

* The access token (and refresh token) was previously saved to a JSON file with this format:
* See Get Google Drive OAuth2 Access Token

* {
*   "access_token": "ya29.Gls-BsdxTWuenChv ... yzVIrXikkLxu5T6dy4I6GjADFardoz4Lruw",
*   "expires_in": 3600,
*   "refresh_token": "1/tMBJ ... 27D-Hk6rpQYBA",
*   "scope": "https://www.googleapis.com/auth/drive",
*   "token_type": "Bearer"
* }

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJson = CreateObject('Chilkat.JsonObject')
lcTokenFilePath = "qa_data/tokens/googleDrive.json"
loJson.LoadFile(lcTokenFilePath)

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.OAuth2')
loOauth2 = CreateObject('Chilkat.OAuth2')
loOauth2.AccessToken = loJson.StringOf("access_token")
loOauth2.RefreshToken = loJson.StringOf("refresh_token")

loOauth2.AuthorizationEndpoint = "https://accounts.google.com/o/oauth2/v2/auth"
loOauth2.TokenEndpoint = "https://www.googleapis.com/oauth2/v4/token"

*  Replace these with actual values.
loOauth2.ClientId = "GOOGLE-CLIENT-ID"
loOauth2.ClientSecret = "GOOGLE-CLIENT-SECRET"
loOauth2.Scope = "https://www.googleapis.com/auth/drive"

* Use OAuth2 to refresh the access token.
lnSuccess = loOauth2.RefreshAccessToken()
IF (lnSuccess <> 1) THEN
    ? loOauth2.LastErrorText
    RELEASE loJson
    RELEASE loOauth2
    CANCEL
ENDIF

? loOauth2.AccessTokenResponse

* Save the new access token to our JSON file (so we can refresh it again when needed).
loJson.UpdateString("access_token",loOauth2.AccessToken)

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.FileAccess')
loFac = CreateObject('Chilkat.FileAccess')
loFac.WriteEntireTextFile(lcTokenFilePath,loJson.Emit(),"utf-8",0)

? "Access Token Refreshed!"

RELEASE loJson
RELEASE loOauth2
RELEASE loFac