Pascal (Lazarus/Delphi)

PayPal - Cancel Sent Invoice

See more PayPal Examples

Cancels a sent invoice, by ID, and, optionally, sends a notification about the cancellation to the payer, merchant, and Cc: emails.

Note: This example requires Chilkat v9.5.0.65 or greater.

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.StringBuilder,
  Chilkat.Rest,
  Chilkat.JsonObject;

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

procedure RunDemo;
var
  success: Boolean;
  jsonToken: TJsonObject;
  sbAuth: TStringBuilder;
  rest: TRest;
  bAutoReconnect: Boolean;
  json: TJsonObject;
  sbPath: TStringBuilder;
  numReplacements: Integer;
  sbRequestBody: TStringBuilder;
  sbResponseBody: TStringBuilder;

begin
  success := False;

  //  Note: Requires Chilkat v9.5.0.65 or greater.

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

  //  Load our previously obtained access token. (see PayPal OAuth2 Access Token)
  jsonToken := TJsonObject.Create;
  jsonToken.LoadFile('qa_data/tokens/paypal.json');

  //  Build the Authorization request header field value.
  sbAuth := TStringBuilder.Create;
  //  token_type should be "Bearer"
  sbAuth.Append(jsonToken.StringOf('token_type'));
  sbAuth.Append(' ');
  sbAuth.Append(jsonToken.StringOf('access_token'));

  //  Make the initial connection.
  //  A single REST object, once connected, can be used for many PayPal REST API calls.
  //  The auto-reconnect indicates that if the already-established HTTPS connection is closed,
  //  then it will be automatically re-established as needed.
  rest := TRest.Create;
  bAutoReconnect := True;
  success := rest.Connect('api.sandbox.paypal.com',443,True,bAutoReconnect);
  if (success <> True) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  //  ----------------------------------------------------------------------------------------------
  //  The code above this comment could be placed inside a function/subroutine within the application
  //  because the connection does not need to be made for every request.  Once the connection is made
  //  the app may send many requests..
  //  ----------------------------------------------------------------------------------------------

  //  Build the JSON request body containing the reminder information:
  json := TJsonObject.Create;
  json.EmitCompact := False;
  json.UpdateString('subject','Past due');
  json.UpdateString('note','Canceling invoice');
  json.UpdateBool('send_to_merchant',True);
  json.UpdateBool('send_to_payer',True);
  WriteLn(json.Emit());

  //  The JSON created by the above code:

  //  	{ 
  //  	  "subject": "Past due",
  //  	  "note": "Canceling invoice",
  //  	  "send_to_merchant": true,
  //  	  "send_to_payer": true
  //  	}

  //  Build a path using a previously-sent invoice ID.
  sbPath := TStringBuilder.Create;
  sbPath.Append('/v1/invoicing/invoices/invoice_id/cancel');
  numReplacements := sbPath.Replace('invoice_id','INV2-XPWZ-NUTQ-LNWB-P8NC');

  json.EmitCompact := True;
  sbRequestBody := TStringBuilder.Create;
  sbResponseBody := TStringBuilder.Create;

  rest.AddHeader('Content-Type','application/json');
  rest.AddHeader('Authorization',sbAuth.GetAsString());
  json.EmitSb(sbRequestBody);

  success := rest.FullRequestSb('POST',sbPath.GetAsString(),sbRequestBody,sbResponseBody);
  if (success <> True) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  WriteLn('Response Status Code = ' + rest.ResponseStatusCode);

  //  In our testing, we received a 204 response, which is a success HTTP response code, but 
  //  differs from the PayPal REST API reference documentation, which states that a 202 response
  //  is expected.  I suspect an error in the PayPal documentation, or in the PayPal responder.
  //  Check for either 202 or 204..
  //  Did we get a 202 accepted response?
  if ((rest.ResponseStatusCode <> 202) and (rest.ResponseStatusCode <> 204)) then
    begin
      WriteLn(sbResponseBody.GetAsString());
      WriteLn('Failed.');
      Exit;
    end;

  //  The 202/204 response should be empty.  (Again, our experience differs from the online PayPal documentation..)
  WriteLn('Success.');


  jsonToken.Free;
  sbAuth.Free;
  rest.Free;
  json.Free;
  sbPath.Free;
  sbRequestBody.Free;
  sbResponseBody.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.