Delphi DLL

Twitter API v2 - Get OAuth2 Access Token

Demonstrates how to get a Twitter API v2 OAuth2 access token from a desktop application or script.

This example is deprecated and no longer valid.

Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, FileAccess, OAuth2, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
oauth2: HCkOAuth2;
url: PWideChar;
numMsWaited: Integer;
json: HCkJsonObject;
fac: HCkFileAccess;

begin
success := False;

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

oauth2 := CkOAuth2_Create();

// This should be the port in the localhost callback URI for your App (defined in the Twitter Developer Portal)
// The Callback URI / Redirect URL should be "http://localhost:3017/" if the port number is 3017.
CkOAuth2_putListenPort(oauth2,3017);

CkOAuth2_putAuthorizationEndpoint(oauth2,'https://twitter.com/i/oauth2/authorize');
CkOAuth2_putTokenEndpoint(oauth2,'https://api.twitter.com/2/oauth2/token');

// Replace these with actual values.
CkOAuth2_putClientId(oauth2,'CLIENT_ID');
CkOAuth2_putClientSecret(oauth2,'CLIENT_SECRET');

CkOAuth2_putScope(oauth2,'tweet.read users.read follows.read follows.write');

CkOAuth2_AddAuthQueryParam(oauth2,'offline.access','');
CkOAuth2_AddAuthQueryParam(oauth2,'state','state');
CkOAuth2_putCodeChallenge(oauth2,True);
CkOAuth2_putCodeChallengeMethod(oauth2,'plain');
CkOAuth2_putUseBasicAuth(oauth2,True);

// Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
url := CkOAuth2__startAuth(oauth2);
if (CkOAuth2_getLastMethodSuccess(oauth2) = False) then
  begin
    Memo1.Lines.Add(CkOAuth2__lastErrorText(oauth2));
    Exit;
  end;

Memo1.Lines.Add(url);

// Launch the system's default browser navigated to the URL.
success := CkOAuth2_LaunchBrowser(oauth2,url);
if (success = False) then
  begin
    Memo1.Lines.Add(CkOAuth2__lastErrorText(oauth2));
    Exit;
  end;

// Now wait for the authorization.
// We'll wait for a max of 60 seconds.
numMsWaited := 0;
while (numMsWaited < 60000) and (CkOAuth2_getAuthFlowState(oauth2) < 3) do
  begin
    CkOAuth2_SleepMs(oauth2,100);
    numMsWaited := numMsWaited + 100;
  end;

// If there was no response from the browser within 60 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 (CkOAuth2_getAuthFlowState(oauth2) < 3) then
  begin
    CkOAuth2_Cancel(oauth2);
    Memo1.Lines.Add('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 (CkOAuth2_getAuthFlowState(oauth2) = 5) then
  begin
    Memo1.Lines.Add('OAuth2 failed to complete.');
    Memo1.Lines.Add(CkOAuth2__failureInfo(oauth2));
    Exit;
  end;

if (CkOAuth2_getAuthFlowState(oauth2) = 4) then
  begin
    Memo1.Lines.Add('OAuth2 authorization was denied.');
    Memo1.Lines.Add(CkOAuth2__accessTokenResponse(oauth2));
    Exit;
  end;

if (CkOAuth2_getAuthFlowState(oauth2) <> 3) then
  begin
    Memo1.Lines.Add('Unexpected AuthFlowState:' + IntToStr(CkOAuth2_getAuthFlowState(oauth2)));
    Exit;
  end;

Memo1.Lines.Add('OAuth2 authorization granted!');
Memo1.Lines.Add('Access Token = ' + CkOAuth2__accessToken(oauth2));

// Get the full JSON response:
json := CkJsonObject_Create();
CkJsonObject_Load(json,CkOAuth2__accessTokenResponse(oauth2));
CkJsonObject_putEmitCompact(json,False);

// The JSON response looks like this:

// {
//   "token_type": "bearer",
//   "expires_in": 7200,
//   "access_token": "NnAfRUxCVWhLNDB3MFRvd25yQlNnelRZY1F1WkFlQqVfNXYwOEVobVNqR0VfOjf2NTg4NDk0MjMxnzE6MTowOmF2OjE",
//   "scope": "users.read follows.read tweet.read follows.write"
// }

Memo1.Lines.Add(CkJsonObject__emit(json));

// Save the JSON to a file for future requests.
fac := CkFileAccess_Create();
CkFileAccess_WriteEntireTextFile(fac,'qa_data/tokens/twitter_v2_oauth2.json',CkJsonObject__emit(json),'utf-8',False);

CkOAuth2_Dispose(oauth2);
CkJsonObject_Dispose(json);
CkFileAccess_Dispose(fac);

end;