Pascal (Lazarus/Delphi)

Google OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to get a Google OAuth2 access token from a desktop application or script. Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.OAuth2,
  Chilkat.StringBuilder;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  oauth2: TOAuth2;
  url: string;
  numMsWaited: Integer;
  sbJson: TStringBuilder;

begin
  success := False;

  //  To further clarify, see OAuth 2.0 Authorization Flow

  oauth2 := TOAuth2.Create;

  //  For Google OAuth2, set the listen port equal to the port used
  //  in the Authorized Redirect URL for the Client ID.
  //  For example, in this case the Authorized Redirect URL would be http://localhost:55568/
  //  Your app should choose a port not likely not used by another application.
  oauth2.ListenPort := 55568;

  oauth2.AuthorizationEndpoint := 'https://accounts.google.com/o/oauth2/v2/auth';
  oauth2.TokenEndpoint := 'https://www.googleapis.com/oauth2/v4/token';

  //  Replace this with your actual client ID.
  oauth2.ClientId := 'GOOGLE-CLIENT-ID';

  //  This is the scope for Google Drive.
  //  See https://developers.google.com/identity/protocols/googlescopes
  //  Add the scopes that you need.
  oauth2.Scope := 'https://www.googleapis.com/auth/drive';

  //  Begin the OAuth2 authorization code flow.  This returns a URL that should be loaded in a browser.
  url := oauth2.StartAuth();
  if (oauth2.LastMethodSuccess <> True) then
    begin
      WriteLn(oauth2.LastErrorText);
      Exit;
    end;

  //  Launch the default browser on the system and navigate to the url.
  //  The LaunchBrowser method was added in Chilkat v10.1.2.
  success := oauth2.LaunchBrowser(url);
  if (success = False) then
    begin
      WriteLn(oauth2.LastErrorText);
      Exit;
    end;

  //  Wait for the interactive user to grant permission in the interactive browser session.
  //  We'll wait for a max of 90 seconds.
  numMsWaited := 0;
  while (numMsWaited < 90000) and (oauth2.AuthFlowState < 3) do
    begin
      oauth2.SleepMs(100);
      numMsWaited := numMsWaited + 100;
    end;

  //  If there was no response from the browser within 90 seconds, then 
  //  the AuthFlowState will be equal to 1 or 2.
  //  1: Waiting for Redirect. The OAuth2 background thread is waiting to receive the redirect HTTP request from the browser.
  //  2: Waiting for Final Response. The OAuth2 background thread is waiting for the final access token response.
  //  In that case, cancel the background task started in the call to StartAuth.
  if (oauth2.AuthFlowState < 3) then
    begin
      oauth2.Cancel();
      WriteLn('No response from the browser!');
      Exit;
    end;

  //  Check the AuthFlowState to see if authorization was granted, denied, or if some error occurred
  //  The possible AuthFlowState values are:
  //  3: Completed with Success. The OAuth2 flow has completed, the background thread exited, and the successful JSON response is available in AccessTokenResponse property.
  //  4: Completed with Access Denied. The OAuth2 flow has completed, the background thread exited, and the error JSON is available in AccessTokenResponse property.
  //  5: Failed Prior to Completion. The OAuth2 flow failed to complete, the background thread exited, and the error information is available in the FailureInfo property.
  if (oauth2.AuthFlowState = 5) then
    begin
      WriteLn('OAuth2 failed to complete.');
      WriteLn(oauth2.FailureInfo);
      Exit;
    end;

  if (oauth2.AuthFlowState = 4) then
    begin
      WriteLn('OAuth2 authorization was denied.');
      WriteLn(oauth2.AccessTokenResponse);
      Exit;
    end;

  if (oauth2.AuthFlowState <> 3) then
    begin
      WriteLn('Unexpected AuthFlowState:' + oauth2.AuthFlowState);
      Exit;
    end;

  //  Save the full JSON access token response to a file.
  sbJson := TStringBuilder.Create;
  sbJson.Append(oauth2.AccessTokenResponse);
  sbJson.WriteFile('qa_data/tokens/_googleDrive.json','utf-8',False);

  //  The saved JSON response looks like this:

  //  	{
  //  	 "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtBBBHkZzrwlARkwX6R3O0PCDEzRlfaQ",
  //  	 "token_type": "Bearer",
  //  	 "expires_in": 3600,
  //  	 "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
  //  	}
  //  
  WriteLn('OAuth2 authorization granted!');
  WriteLn('Access Token = ' + oauth2.AccessToken);

  //  Here is an example showing how to define your OAuth 2.0 Credential in the Google Cloud Console
  //  Note: Even though your application is technically not a web app, you should still select "Web Application"
  //  because the Redirect URI is going to http://localhost:55568/ where Chilkat will receive it in a background thread.

  //  


  oauth2.Free;
  sbJson.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.