(Delphi ActiveX) 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 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;
sbJsonRequest: TChilkatStringBuilder;
sbJsonResponse: TChilkatStringBuilder;
json: TChilkatJsonObject;

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

// 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 := TChilkatStringBuilder.Create(Self);
sbJsonResponse := TChilkatStringBuilder.Create(Self);
success := rest.FullRequestSb('POST','/v1/invoicing/invoices/next-invoice-number',sbJsonRequest.ControlInterface,sbJsonResponse.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);
    Exit;
  end;

json := TChilkatJsonObject.Create(Self);
json.EmitCompact := 0;
json.LoadSb(sbJsonResponse.ControlInterface);

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

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

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

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

// 	{ 
// 	  "number": "0003"
// 	}
end;