Xbase++

Refresh GMail OAuth2 Access Token

See more GMail REST API Examples

Demonstrates how to refresh an expired or soon-to-expire GMail OAuth2 access token. Xbase++

LOCAL nSuccess
LOCAL oJsonToken
LOCAL oOauth2
LOCAL oSbJson

nSuccess := 0

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

//  It is assumed we previously obtained an OAuth2 access token.
//  This example loads the JSON access token file 
//  saved by this example: Get GMail OAuth2 Access Token

oJsonToken := CreateObject("Chilkat.JsonObject")
nSuccess := oJsonToken:LoadFile("qa_data/tokens/gmail.json")
IF (nSuccess != 1)
    ? "Failed to load googleSheets.json"
    oJsonToken:destroy()
    RETURN
ENDIF

//  The access token JSON looks like this:

//  	{ 
//  	 "access_token": "abac.Ci-ZabcdF37-VUrmSzxbHxTsMbtlN-uPfabcdAQN_2ekzj0s5osCzRabcdTDMGaa2Q",
//  	 "token_type": "Bearer",
//  	 "expires_in": 3600,
//  	 "refresh_token": "1/lEe5abcdNJ77eOSDBabcdkQGVmDalkwabcdR2Hatbo"
//  	}
//  

oOauth2 := CreateObject("Chilkat.OAuth2")

oOauth2:TokenEndpoint := "https://www.googleapis.com/oauth2/v4/token"

//  Replace these with actual values.
oOauth2:ClientId := "GOOGLE-CLIENT-ID"
oOauth2:ClientSecret := "GOOGLE-CLIENT-SECRET"

//  Get the "refresh_token"
oOauth2:RefreshToken := oJsonToken:StringOf("refresh_token")

//  Send the HTTP POST to refresh the access token..
nSuccess := oOauth2:RefreshAccessToken()
IF (nSuccess != 1)
    ? oOauth2:LastErrorText
    oJsonToken:destroy()
    oOauth2:destroy()
    RETURN
ENDIF

//  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.
oJsonToken:UpdateString("access_token", oOauth2:AccessToken)

//  Save the new JSON access token response to a file.
oSbJson := CreateObject("Chilkat.StringBuilder")
oJsonToken:EmitCompact := 0
oJsonToken:EmitSb(oSbJson)
oSbJson:WriteFile("qa_data/tokens/gmail.json", "utf-8", 0)

? "OAuth2 authorization granted!"
? "New Access Token = " + oOauth2:AccessToken

oJsonToken:destroy()
oOauth2:destroy()
oSbJson:destroy()