(Classic ASP) Refresh GMail OAuth2 Access Token

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

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

<html>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<%
' 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

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.JsonObject")
set jsonToken = Server.CreateObject("Chilkat.JsonObject")
success = jsonToken.LoadFile("qa_data/tokens/gmail.json")
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( "Failed to load googleSheets.json") & "</pre>"
    Response.End
End If

' 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"
' 	}
' 

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.OAuth2")
set oauth2 = Server.CreateObject("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 <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( oauth2.LastErrorText) & "</pre>"
    Response.End
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.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
set sbJson = Server.CreateObject("Chilkat.StringBuilder")
jsonToken.EmitCompact = 0
success = jsonToken.EmitSb(sbJson)
success = sbJson.WriteFile("qa_data/tokens/gmail.json","utf-8",0)

Response.Write "<pre>" & Server.HTMLEncode( "OAuth2 authorization granted!") & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "New Access Token = " & oauth2.AccessToken) & "</pre>"

%>
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