(Delphi DLL) PayPal - Generate Invoice Number

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

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;
sbJsonRequest: HCkStringBuilder;
sbJsonResponse: HCkStringBuilder;
json: HCkJsonObject;

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

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

CkRest_AddHeader(rest,'Authorization',CkStringBuilder__getAsString(sbAuth));

// Send the POST request with an emtpy body and get the JSON response.
sbJsonRequest := CkStringBuilder_Create();
sbJsonResponse := CkStringBuilder_Create();
success := CkRest_FullRequestSb(rest,'POST','/v1/invoicing/invoices/next-invoice-number',sbJsonRequest,sbJsonResponse);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

json := CkJsonObject_Create();
CkJsonObject_putEmitCompact(json,False);
CkJsonObject_LoadSb(json,sbJsonResponse);

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

// Did we get a 200 success response?
if (CkRest_getResponseStatusCode(rest) <> 200) then
  begin
    Memo1.Lines.Add(CkJsonObject__emit(json));
    Memo1.Lines.Add('Failed.');
    Exit;
  end;

// Sample JSON response is shown below.
Memo1.Lines.Add(CkJsonObject__emit(json));
Memo1.Lines.Add('----------------------');
Memo1.Lines.Add('Next invoice number: ' + CkJsonObject__stringOf(json,'number'));
Memo1.Lines.Add('success');

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

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

CkJsonObject_Dispose(jsonToken);
CkStringBuilder_Dispose(sbAuth);
CkRest_Dispose(rest);
CkStringBuilder_Dispose(sbJsonRequest);
CkStringBuilder_Dispose(sbJsonResponse);
CkJsonObject_Dispose(json);

end;