Pascal (Lazarus/Delphi)

Refresh OAuth2 Access Token with Optional Params

See more OAuth2 Examples

Demonstrates how to refresh an OAuth2 access token with optional query params included in the HTTP request. 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,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  jsonToken: TJsonObject;
  oauth2: TOAuth2;
  sbJson: TStringBuilder;

begin
  success := False;

  //  Here is a sampling of possible optional parameters that might
  //  be used by some OAuth2 providers.

  //  Optional Parameters
  //  
  //      "scope":
  //          Specifies the scope of the access request. If omitted, the authorization
  //          server may issue a token with the same scope as the original token.
  //          Example: "scope=read write"
  //  
  //      "redirect_uri":
  //          The redirect URI used in the original authorization request. Some
  //          servers may require this for validation.
  //          Example: "redirect_uri=https://example.com/callback"
  //  
  //      "resource":
  //          Indicates the target resource or audience for the token. This is used in
  //          some implementations (e.g., Microsoft Identity Platform).
  //          Example: "resource=https://api.example.com"
  //  
  //      "audience":
  //          Similar to "resource", this specifies the intended audience for the
  //          token (used in some OAuth2 implementations like Auth0).
  //          Example: "audience=https://api.example.com"
  //  
  //      "client_assertion" and "client_assertion_type":
  //          Used for client authentication using a signed JWT instead of a client
  //          secret.
  //          Example:client_assertion=eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...        
  //          client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer
  //  
  //      "token_type_hint":
  //          Provides a hint to the authorization server about the type of token
  //          being refreshed. This is rarely used but can be helpful in some cases.
  //          Example: "token_type_hint=refresh_token"
  //  
  //      "assertion":
  //          Used in some flows (e.g., SAML bearer assertion flow) to provide an
  //          assertion for token issuance.
  //          Example: "assertion=PHNhbWxwOl..."
  //  
  //      "requested_token_use":
  //          Specifies how the token will be used (e.g., "on_behalf_of" in the
  //          On-Behalf-Of flow used by Microsoft Identity Platform).
  //          Example: "requested_token_use=on_behalf_of"
  //  

  //  --------------------------------------------------------------------------------
  //  This example wll refresh the access token and includes the "audience"
  //  optional query parameter.
  //  
  //  

  //  Get the access token to be refreshed.
  jsonToken := TJsonObject.Create;
  success := jsonToken.LoadFile('qa_data/tokens/myAccessToken.json');
  if (success <> True) then
    begin
      WriteLn('Failed to load hmrc.json');
      Exit;
    end;

  oauth2 := TOAuth2.Create;

  oauth2.TokenEndpoint := 'https://api.example.com/oauth/token';

  //  Replace these with actual values.
  oauth2.ClientId := 'CLIENT_ID';
  oauth2.ClientSecret := 'CLIENT_SECRET';

  //  Add the optional refresh query param.
  //  Call AddRefreshQueryParam multiple times to add additional params.
  oauth2.AddRefreshQueryParam('audience','https://api.example.com');

  //  Provide the existing refresh token from the JSON.
  oauth2.RefreshToken := jsonToken.StringOf('refresh_token');

  //  Send the HTTP POST to refresh the access token..
  success := oauth2.RefreshAccessToken();
  if (success <> True) then
    begin
      WriteLn(oauth2.LastErrorText);
      Exit;
    end;

  //  Load the access token response into the json object 
  jsonToken.Load(oauth2.AccessTokenResponse);

  //  Save the new JSON access token response to a file.
  //  The access + refresh tokens contained in this JSON will be needed for the next refresh.
  sbJson := TStringBuilder.Create;
  jsonToken.EmitCompact := False;
  jsonToken.EmitSb(sbJson);
  sbJson.WriteFile('qa_data/tokens/myAccessToken.json','utf-8',False);

  WriteLn('OAuth2 access token refreshed!');
  WriteLn('New Access Token = ' + oauth2.AccessToken);


  jsonToken.Free;
  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.