(PowerBuilder) Google Calendar -- Refresh an Expired Access Token

See more Google Calendar Examples

Demonstrates how to refresh an expired access token. If a Google Calendar REST API call results in a 401 "unauthorized" response, then it is likely the access token expired. An application should be able to automatically refresh the access token with no user interaction and then re-try the request with the newly obtained access token.

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

integer li_rc
oleobject loo_JsonToken
integer li_Success
oleobject loo_Oauth2
oleobject loo_SbJson

// 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 Google Calendar OAuth2 Access Token

loo_JsonToken = create oleobject
// Use "Chilkat_9_5_0.JsonObject" for versions of Chilkat < 10.0.0
li_rc = loo_JsonToken.ConnectToNewObject("Chilkat.JsonObject")
if li_rc < 0 then
    destroy loo_JsonToken
    MessageBox("Error","Connecting to COM object failed")
    return
end if
li_Success = loo_JsonToken.LoadFile("qa_data/tokens/googleCalendar.json")
if li_Success <> 1 then
    Write-Debug "Failed to load googleCalendar.json"
    destroy loo_JsonToken
    return
end if

// The access token JSON looks like this:

// 	{ 
// 	 "access_token": "abac.Ci-ZabcdF37-NUrmSzxbHxTsMbtlN-uPfabcdAQN_2ekzj0s5ofCzRabcdTDMGaa2Q",
// 	 "token_type": "Bearer",
// 	 "expires_in": 3600,
// 	 "refresh_token": "1/lEe5abcdNJ77eOSDBabcdkQGVmDalkwabcdR2Hatbo"
// 	}
// 

loo_Oauth2 = create oleobject
// Use "Chilkat_9_5_0.OAuth2" for versions of Chilkat < 10.0.0
li_rc = loo_Oauth2.ConnectToNewObject("Chilkat.OAuth2")

loo_Oauth2.TokenEndpoint = "https://www.googleapis.com/oauth2/v4/token"

// Replace these with actual values.
loo_Oauth2.ClientId = "GOOGLE-CLIENT-ID"
loo_Oauth2.ClientSecret = "GOOGLE-CLIENT-SECRET"

// Get the "refresh_token"
loo_Oauth2.RefreshToken = loo_JsonToken.StringOf("refresh_token")

// Send the HTTP POST to refresh the access token..
li_Success = loo_Oauth2.RefreshAccessToken()
if li_Success <> 1 then
    Write-Debug loo_Oauth2.LastErrorText
    destroy loo_JsonToken
    destroy loo_Oauth2
    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.
loo_JsonToken.UpdateString("access_token",loo_Oauth2.AccessToken)

// Save the new JSON access token response to a file.
loo_SbJson = create oleobject
// Use "Chilkat_9_5_0.StringBuilder" for versions of Chilkat < 10.0.0
li_rc = loo_SbJson.ConnectToNewObject("Chilkat.StringBuilder")

loo_JsonToken.EmitCompact = 0
loo_JsonToken.EmitSb(loo_SbJson)
loo_SbJson.WriteFile("qa_data/tokens/googleCalendar.json","utf-8",0)

Write-Debug "OAuth2 authorization granted!"
Write-Debug "New Access Token = " + loo_Oauth2.AccessToken


destroy loo_JsonToken
destroy loo_Oauth2
destroy loo_SbJson