(Visual Basic 6.0) MercadoLibre Refresh OAuth2 Access Token

Demonstrates how to refresh a MercadoLibre OAuth2 access token. The refresh does not require user interaction via a web browser. If an access token expires (typically with a 401 response code), a new access token can be automatically obtained by using the code in this example.

For more information, see https://developers.mercadolibre.com.ar/es_ar/autenticacion-y-autorizacion#Refresh-token

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

' 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 MercadoLibre OAuth2 Access Token

Dim jsonToken As New ChilkatJsonObject
Dim success As Long
success = jsonToken.LoadFile("qa_data/tokens/mercadolibre.json")
If (success <> 1) Then
    Debug.Print "Failed to load mercadolibre.json"
    Exit Sub
End If

' The access token JSON looks like this:

' {
'   "access_token": "APP_USR-8133606632685744-060115-93e1fd8b5e767c51c238df347bd0b288-577628017",
'   "token_type": "bearer",
'   "expires_in": 21600,
'   "scope": "offline_access read write",
'   "user_id": 577625107,
'   "refresh_token": "TG-5ad522a286f1200006ac4ed1-577625007"
' }

Dim oauth2 As New ChilkatOAuth2

oauth2.TokenEndpoint = "https://api.mercadolibre.com/oauth/token"

' Replace these with actual values.
oauth2.ClientId = "MY_MERCADOLIBRE_APP_ID"
oauth2.ClientSecret = "MY_MERCADOLIBRE_APP_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
    Debug.Print oauth2.LastErrorText
    Exit Sub
End If

Debug.Print "New access token: " & oauth2.AccessToken
Debug.Print "New refresh token: " & oauth2.RefreshToken

' Update the JSON with the new tokens.
success = jsonToken.UpdateString("access_token",oauth2.AccessToken)
success = jsonToken.UpdateString("refresh_token",oauth2.RefreshToken)

' Save the new JSON access token response to a file.
Dim sbJson As New ChilkatStringBuilder
jsonToken.EmitCompact = 0
success = jsonToken.EmitSb(sbJson)
success = sbJson.WriteFile("qa_data/tokens/mercadolibre.json","utf-8",0)

Debug.Print "OAuth2 authorization granted!"
Debug.Print "New Access Token = " & oauth2.AccessToken