(Delphi ActiveX) PayPal - Cancel Sent Invoice

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.

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
jsonToken: TChilkatJsonObject;
sbAuth: TChilkatStringBuilder;
rest: TChilkatRest;
bAutoReconnect: Integer;
success: Integer;
json: TChilkatJsonObject;
sbPath: TChilkatStringBuilder;
numReplacements: Integer;
sbRequestBody: TChilkatStringBuilder;
sbResponseBody: TChilkatStringBuilder;

begin
// 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 := TChilkatJsonObject.Create(Self);
jsonToken.LoadFile('qa_data/tokens/paypal.json');

// Build the Authorization request header field value.
sbAuth := TChilkatStringBuilder.Create(Self);
// 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 := TChilkatRest.Create(Self);
bAutoReconnect := 1;
success := rest.Connect('api.sandbox.paypal.com',443,1,bAutoReconnect);
if (success <> 1) then
  begin
    Memo1.Lines.Add(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 := TChilkatJsonObject.Create(Self);
json.EmitCompact := 0;
json.UpdateString('subject','Past due');
json.UpdateString('note','Canceling invoice');
json.UpdateBool('send_to_merchant',1);
json.UpdateBool('send_to_payer',1);
Memo1.Lines.Add(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 := TChilkatStringBuilder.Create(Self);
sbPath.Append('/v1/invoicing/invoices/invoice_id/cancel');
numReplacements := sbPath.Replace('invoice_id','INV2-XPWZ-NUTQ-LNWB-P8NC');

json.EmitCompact := 1;
sbRequestBody := TChilkatStringBuilder.Create(Self);
sbResponseBody := TChilkatStringBuilder.Create(Self);

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

success := rest.FullRequestSb('POST',sbPath.GetAsString(),sbRequestBody.ControlInterface,sbResponseBody.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Response Status Code = ' + IntToStr(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
    Memo1.Lines.Add(sbResponseBody.GetAsString());
    Memo1.Lines.Add('Failed.');
    Exit;
  end;

// The 202/204 response should be empty.  (Again, our experience differs from the online PayPal documentation..)
Memo1.Lines.Add('Success.');
end;