(Delphi DLL) Get Access Token for Google Tasks using Service Account JSON Key

Demonstrates how to get an access token for the Google Tasks API using a Service Account JSON key.

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
fac: HCkFileAccess;
jsonKey: PWideChar;
gAuth: HCkAuthGoogle;
tlsSock: HCkSocket;
success: Boolean;

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

// First load the JSON key into a string.
fac := CkFileAccess_Create();
jsonKey := CkFileAccess__readEntireTextFile(fac,'qa_data/googleSvcAccountKeys/ChilkatCloud-48f7737c7505.json','utf-8');
if (CkFileAccess_getLastMethodSuccess(fac) <> True) then
  begin
    Memo1.Lines.Add(CkFileAccess__lastErrorText(fac));
    Exit;
  end;

// A JSON private key should look like this:

// {
//   "type": "service_account",
//   "project_id": "chilkatcloud",
//   "private_key_id": "48f7737c7505bb88eee6a20d09993e10605d466e",
//   "private_key": "-----BEGIN PRIVATE KEY----- ... -----END PRIVATE KEY-----\n",
//   "client_email": "pip-564@chilkatcloud.iam.gserviceaccount.com",
//   "client_id": "109982228323456925225",
//   "auth_uri": "https://accounts.google.com/o/oauth2/auth",
//   "token_uri": "https://oauth2.googleapis.com/token",
//   "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
//   "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/pip-564%40chilkatcloud.iam.gserviceaccount.com"
// }

gAuth := CkAuthGoogle_Create();
CkAuthGoogle_putJsonKey(gAuth,jsonKey);

// Choose the scope for read/write access.
CkAuthGoogle_putScope(gAuth,'https://www.googleapis.com/auth/tasks');

// Request an access token that is valid for this many seconds.
CkAuthGoogle_putExpireNumSeconds(gAuth,3600);

CkAuthGoogle_putSubEmailAddress(gAuth,'');

// Connect to www.googleapis.com using TLS
tlsSock := CkSocket_Create();
success := CkSocket_Connect(tlsSock,'www.googleapis.com',443,True,5000);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tlsSock));
    Exit;
  end;

// Send the request to obtain the access token.
success := CkAuthGoogle_ObtainAccessToken(gAuth,tlsSock);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkAuthGoogle__lastErrorText(gAuth));
    Exit;
  end;

// Examine the access token:
Memo1.Lines.Add('Access Token: ' + CkAuthGoogle__accessToken(gAuth));

// Save our access token to a file.
success := CkFileAccess_WriteEntireTextFile(fac,'qa_data/tokens/googleTasks.txt',CkAuthGoogle__accessToken(gAuth),'utf-8',False);

CkFileAccess_Dispose(fac);
CkAuthGoogle_Dispose(gAuth);
CkSocket_Dispose(tlsSock);

end;