Paypal Payment Request error - delphi

Question

Here is my code regarding the PayPal Payment Request. I am getting a 401 error but I am not sure where it is coming from or how to handle it. I believe it is from my Custom Header configuration.
How to fix it?
FUNCTION GetAccessToken :String ;
Var
AccessToken :TJSONValue ;
BEGIN
AccessToken := PayPalTokenObj.Get('access_token').JsonValue ;
Result := AccessToken.Value ;
PayPalForm.Memo1.Lines.Add('Access Token: ' + Result) ;
END ; {GetAccessToken}
FUNCTION GetTokenType :String ;
Var
AccessTokenType :TJSONValue ;
BEGIN
AccessTokenType := PayPalTokenObj.Get('token_type').JsonValue ;
Result := AccessTokenType.Value ;
PayPalForm.Memo1.Lines.Add('Token Type: ' + Result) ;
END ; {GetTokenType}
procedure SendPayment;
const
PaymentRequest = 'https://api.sandbox.paypal.com/v1/payments/payment';
var
PayPalPaymentRequestObj, PayerObj, AmountObj, TransactionObj, RedirectObj: TJSONObject;
TransactionsArray :TJSONArray ;
InputJSON: TStringStream;
Result :String ;
begin
//Create a JSON object called PayPalPaymentRequest
PayPalPaymentRequestObj := TJSONObject.Create;
try
PayPalPaymentRequestObj.AddPair(TJSONPair.Create('intent', TJSONString.Create('sale'))) ;
RedirectObj := TJSONObject.Create;
try
PayPalPaymentRequestObj.AddPair('redirect_urls', RedirectObj);
RedirectObj.AddPair(TJSONPair.Create('return_url', TJSONString.Create('http://www.SoftwareMomentum.com')));
RedirectObj.AddPair(TJSONPair.Create('cancel_url', TJSONString.Create('http://www.Yahoo.com')));
except
RedirectObj.Free;
raise;
end;
PayerObj := TJSONObject.Create;
try
PayPalPaymentRequestObj.AddPair('payer', PayerObj);
PayerObj.AddPair(TJSONPair.Create('payment_method', TJSONString.Create('paypal')));
except
PayerObj.Free;
raise;
end;
TransactionsArray := TJSONArray.Create;
AmountObj := TJSONObject.Create;
TransactionObj := TJSONObject.Create;
try
PayPalPaymentRequestObj.AddPair('transactions', TransactionsArray) ;
AmountObj.AddPair(TJSONPair.Create('total', TJSONString.Create('7.47')));
AmountObj.AddPair(TJSONPair.Create('currency', TJSONString.Create('USD')));
TransactionObj.AddPair('amount', AmountObj);
TransactionObj.AddPair(TJSONPair.Create('description', TJSONString.Create('payment description')));
// TransactionsArray.Add(AmountObj);
TransactionsArray.Add(TransactionObj);
except
TransactionsArray.Free;
AmountObj.Free;
TransactionObj.Free;
Exit;
end;
with Http do
begin
Request.Clear;
Request.CustomHeaders.Clear ;
Request.BasicAuthentication := False;
Request.CustomHeaders.Values['Authorization'] := Format(GetTokenType + ' %s', [GetAccessToken]);
Request.ContentType := 'application/json';
Request.Accept := 'application/json' ;
Request.ContentLength := 431 ;
Request.UserAgent := 'PayPalSDK/NIW/HATEOAS' ;
end; {with}
InputJSON := TStringStream.Create(PayPalPaymentRequestObj.ToString, TEncoding.UTF8);
try
HTTP.ProtocolVersion := pv1_1 ;
HTTP.AllowCookies := True ;
HTTP.HandleRedirects := True ;
//Result := HTTP.Post(PaymentRequest, PostData);
Result := HTTP.Post(PaymentRequest, InputJSON) ;
finally
InputJSON.Free;
end ; {try-finally}
finally
PayPalPaymentRequestObj.Free;
end ; {try-finally}
end;

Answer 1

You are ignoring the server's actual response. Your code is assuming that the response gets written to the same TStream that the request data is provided from, but that is not the case.
You are calling the version of Post() that takes a TStream as input and returns a String as output:
function Post(AURL: string; ASource: TStream): string; overload;
You are ignoring the returned String and instead using your original request data, thus the echoing that you are experiencing. The server is not echoing the request back to you, you are simply processing whatever you send as if it was returned.
You need to change this code:
HTTP.Post(PaymentRequest, Response) ;
Result := Response.DataString ;
To this instead:
Result := HTTP.Post(PaymentRequest, Response);
You should then rename the Response variable to a more suitable name. And also clean up your memory management as well, as you have some memory leaks if something goes wrong.
Try something like this:
procedure SendPayment;
const
PaymentRequest = 'https://api.sandbox.paypal.com/v1/payments/payment';
var
PayPalPaymentRequestObj, PayerObj, AmountObj, TransactionObj, RedirectObj: TJSONObject;
TransactionsArray: TJSONArray;
InputJSON: TStringStream;
Result: String;
begin
//Create a JSON object called PayPalPaymentRequest
PayPalPaymentRequestObj := TJSONObject.Create;
try
PayPalPaymentRequestObj.AddPair('intent', 'sale');
RedirectObj := TJSONObject.Create;
try
RedirectObj.AddPair('return_url', 'http://www.SoftwareMomentum.com');
RedirectObj.AddPair('cancel_url', 'http://www.Yahoo.com');
PayPalPaymentRequestObj.AddPair('redirect_urls', RedirectObj);
except
RedirectObj.Free;
raise;
end;
PayerObj := TJSONObject.Create;
try
PayerObj.AddPair('payment_method', 'paypal');
PayPalPaymentRequestObj.AddPair('payer', PayerObj);
except
PayerObj.Free;
raise;
end;
TransactionsArray := TJSONArray.Create;
try
TransactionObj := TJSONObject.Create;
try
AmountObj := TJSONObject.Create;
try
AmountObj.AddPair('total', '7.47');
AmountObj.AddPair('currency', 'USD');
TransactionObj.AddPair('amount', AmountObj);
except
AmountObj.Free;
raise;
end;
TransactionObj.AddPair('description', 'payment description');
TransactionsArray.Add(TransactionObj);
except
TransactionObj.Free;
raise;
end;
PayPalPaymentRequestObj.AddPair('transactions', TransactionsArray);
except
TransactionsArray.Free;
raise;
end;
with Http do
begin
ProtocolVersion := pv1_1;
AllowCookies := True;
HandleRedirects := True;
Request.Clear;
Request.BasicAuthentication := False;
Request.CustomHeaders.Values['Authorization'] := Format('%s %s', [GetTokenType, GetAccessToken]);
Request.ContentType := 'application/json';
Request.Accept := 'application/json';
Request.UserAgent := 'PayPalSDK/NIW/HATEOAS';
end;
InputJSON := TStringStream.Create(PayPalPaymentRequestObj.ToString, TEncoding.UTF8);
try
Result := HTTP.Post(PaymentRequest, InputJSON);
finally
InputJSON.Free;
end;
finally
PayPalPaymentRequestObj.Free;
end;
end;