(Delphi ActiveX) 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 for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
jsonToken: TChilkatJsonObject;
success: Integer;
oauth2: TChilkatOAuth2;
sbJson: TChilkatStringBuilder;

begin
// 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

jsonToken := TChilkatJsonObject.Create(Self);
success := jsonToken.LoadFile('qa_data/tokens/mercadolibre.json');
if (success <> 1) then
  begin
    Memo1.Lines.Add('Failed to load mercadolibre.json');
    Exit;
  end;

// 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"
// }

oauth2 := TChilkatOAuth2.Create(Self);

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
  begin
    Memo1.Lines.Add(oauth2.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('New access token: ' + oauth2.AccessToken);
Memo1.Lines.Add('New refresh token: ' + oauth2.RefreshToken);

// Update the JSON with the new tokens.
jsonToken.UpdateString('access_token',oauth2.AccessToken);
jsonToken.UpdateString('refresh_token',oauth2.RefreshToken);

// Save the new JSON access token response to a file.
sbJson := TChilkatStringBuilder.Create(Self);
jsonToken.EmitCompact := 0;
jsonToken.EmitSb(sbJson.ControlInterface);
sbJson.WriteFile('qa_data/tokens/mercadolibre.json','utf-8',0);

Memo1.Lines.Add('OAuth2 authorization granted!');
Memo1.Lines.Add('New Access Token = ' + oauth2.AccessToken);
end;