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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
jsonToken: HCkJsonObject;
sbAuth: HCkStringBuilder;
rest: HCkRest;
bAutoReconnect: Boolean;
success: Boolean;
json: HCkJsonObject;
sbPath: HCkStringBuilder;
numReplacements: Integer;
sbRequestBody: HCkStringBuilder;
sbResponseBody: HCkStringBuilder;

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 := CkJsonObject_Create();
CkJsonObject_LoadFile(jsonToken,'qa_data/tokens/paypal.json');

// Build the Authorization request header field value.
sbAuth := CkStringBuilder_Create();
// token_type should be "Bearer"
CkStringBuilder_Append(sbAuth,CkJsonObject__stringOf(jsonToken,'token_type'));
CkStringBuilder_Append(sbAuth,' ');
CkStringBuilder_Append(sbAuth,CkJsonObject__stringOf(jsonToken,'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 := CkRest_Create();
bAutoReconnect := True;
success := CkRest_Connect(rest,'api.sandbox.paypal.com',443,True,bAutoReconnect);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    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 := CkJsonObject_Create();
CkJsonObject_putEmitCompact(json,False);
CkJsonObject_UpdateString(json,'subject','Past due');
CkJsonObject_UpdateString(json,'note','Canceling invoice');
CkJsonObject_UpdateBool(json,'send_to_merchant',True);
CkJsonObject_UpdateBool(json,'send_to_payer',True);
Memo1.Lines.Add(CkJsonObject__emit(json));

// 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 := CkStringBuilder_Create();
CkStringBuilder_Append(sbPath,'/v1/invoicing/invoices/invoice_id/cancel');
numReplacements := CkStringBuilder_Replace(sbPath,'invoice_id','INV2-XPWZ-NUTQ-LNWB-P8NC');

CkJsonObject_putEmitCompact(json,True);
sbRequestBody := CkStringBuilder_Create();
sbResponseBody := CkStringBuilder_Create();

CkRest_AddHeader(rest,'Content-Type','application/json');
CkRest_AddHeader(rest,'Authorization',CkStringBuilder__getAsString(sbAuth));
CkJsonObject_EmitSb(json,sbRequestBody);

success := CkRest_FullRequestSb(rest,'POST',CkStringBuilder__getAsString(sbPath),sbRequestBody,sbResponseBody);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

Memo1.Lines.Add('Response Status Code = ' + IntToStr(CkRest_getResponseStatusCode(rest)));

// 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 ((CkRest_getResponseStatusCode(rest) <> 202) and (CkRest_getResponseStatusCode(rest) <> 204)) then
  begin
    Memo1.Lines.Add(CkStringBuilder__getAsString(sbResponseBody));
    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.');

CkJsonObject_Dispose(jsonToken);
CkStringBuilder_Dispose(sbAuth);
CkRest_Dispose(rest);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbPath);
CkStringBuilder_Dispose(sbRequestBody);
CkStringBuilder_Dispose(sbResponseBody);

end;