Pascal (Lazarus/Delphi)

PayPal - Generate Invoice Number

See more PayPal Examples

Generates the next invoice number that is available to the user.

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;
  sbJsonRequest: TStringBuilder;
  sbJsonResponse: TStringBuilder;
  json: TJsonObject;

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..
  //  ----------------------------------------------------------------------------------------------

  //  Clear the REST object of any headers or query params from previous requests.
  rest.ClearAllHeaders();
  rest.ClearAllQueryParams();

  rest.AddHeader('Authorization',sbAuth.GetAsString());

  //  Send the POST request with an emtpy body and get the JSON response.
  sbJsonRequest := TStringBuilder.Create;
  sbJsonResponse := TStringBuilder.Create;
  success := rest.FullRequestSb('POST','/v1/invoicing/invoices/next-invoice-number',sbJsonRequest,sbJsonResponse);
  if (success <> True) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  json := TJsonObject.Create;
  json.EmitCompact := False;
  json.LoadSb(sbJsonResponse);

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

  //  Did we get a 200 success response?
  if (rest.ResponseStatusCode <> 200) then
    begin
      WriteLn(json.Emit());
      WriteLn('Failed.');
      Exit;
    end;

  //  Sample JSON response is shown below.
  WriteLn(json.Emit());
  WriteLn('----------------------');
  WriteLn('Next invoice number: ' + json.StringOf('number'));
  WriteLn('success');

  //  ------------------------------------------------
  //  A sample JSON response:

  //  	{ 
  //  	  "number": "0003"
  //  	}


  jsonToken.Free;
  sbAuth.Free;
  rest.Free;
  sbJsonRequest.Free;
  sbJsonResponse.Free;
  json.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.