ASP.NET Core Paypal Implementation - asp.net-core

Question

I try to implement a PayPal cart payment in ASP.NET Core. I have a working example in ASP.NET MVC 5 and I try to convert it to ASP.NET Core but I had no success. The point that I can not resolve is how to get the values that I have to get the transactionID, amount paid and Order ID. In ASP.NET MVC 5 the IPN action is as follows:
public ActionResult IPN()
{
System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
var formVals = new Dictionary<string, string>();
formVals.Add("cmd", "_notify-validate");
string response = GetPayPalResponse(formVals, true);
if (response == "VERIFIED")
{
string transactionID = Request["txn_id"];
string sAmountPaid = Request["mc_gross"];
string orderID = Request["custom"];
:
:
In my ASP.NET Core application the IPN action is executed by PayPal and I have a VERIFIED response but I can not get the next three values. I have tried various ways to get these values without success.
My initial approach was the following:
string transactionID = Request.Query["txn_id"];
string sAmountPaid = Request.Query["mc_gross"];
string orderID = Request.Query["custom"];
Can someone suggest me a way to get these values?

Answer 1

I found a solution to my problem and I will post it just in case someone wants to do something similar.
[Route("PayPal/IPN")]
[HttpPost]
public ActionResult IPN()
{
System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
PayPalRespond response = GetPayPalResponse();
if (response.RespondType == RespondTypeEnum.Verified)
{
System.IO.File.AppendAllText(_env.WebRootPath + Path.DirectorySeparatorChar.ToString() + "data.txt", $"{DateTime.Now.ToString()} {response.JsonData}." + Environment.NewLine);
Order order = GetOrder(154);
//check the amount paid
if (order.Total <= response.AmountPaid)
{
// IPN Order successfully transacted. Save changes to database
return Ok();
}
else
{
// Amount Paid is incorrect
}
}
else
{
// Not verified
}
return Content("");
}
PayPalRespond GetPayPalResponse()
{
PayPalRespond output = new PayPalRespond();
var formVals = new Dictionary<string, string>();
formVals.Add("cmd", "_notify-validate");
string paypalUrl = UseSandbox ? "https://www.sandbox.paypal.com/cgi-bin/webscr" : "https://www.paypal.com/cgi-bin/webscr";
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(paypalUrl);
// Set values for the request back
req.Method = "POST";
req.ContentType = "application/x-www-form-urlencoded";
byte[] param;
using (var ms = new MemoryStream(2048))
{
Request.Body.CopyTo(ms);
param = ms.ToArray();
}
string strRequest = Encoding.ASCII.GetString(param);
var QueryValues = System.Web.HttpUtility.ParseQueryString(strRequest);
output.Data = new List<QueryValue>();
foreach (var item in QueryValues.AllKeys)
{
if (item.Equals("txn_id"))
output.TransactionID = QueryValues[item];
else if (item.Equals("mc_gross"))
{
CultureInfo culture = CultureInfo.CreateSpecificCulture("en-US");
NumberStyles style = NumberStyles.Number;
Decimal amountPaid = 0;
Decimal.TryParse(QueryValues[item], style, culture, out amountPaid);
output.AmountPaid = amountPaid;
}
else if (item.Equals("custom"))
output.OrderID = QueryValues[item];
output.Data.Add(new QueryValue { Name = item, Value = QueryValues[item] });
}
output.JsonData = Newtonsoft.Json.JsonConvert.SerializeObject(output.Data);
StringBuilder sb = new StringBuilder();
sb.Append(strRequest);
foreach (string key in formVals.Keys)
{
sb.AppendFormat("&{0}={1}", key, formVals[key]);
}
strRequest += sb.ToString();
req.ContentLength = strRequest.Length;
//Send the request to PayPal and get the response
string response = "";
using (StreamWriter streamOut = new StreamWriter(req.GetRequestStream(), System.Text.Encoding.ASCII))
{
streamOut.Write(strRequest);
streamOut.Close();
using (StreamReader streamIn = new StreamReader(req.GetResponse().GetResponseStream()))
{
response = streamIn.ReadToEnd();
}
}
output.RespondType = response.Equals("VERIFIED") ? RespondTypeEnum.Verified : RespondTypeEnum.Invalid;
return output;
}
The enumerator and the classes that you will need are the following:
public enum RespondTypeEnum { Verified, Invalid }
public class PayPalRespond
{
public RespondTypeEnum RespondType { get; set; }
public List<QueryValue> Data { get; set; }
public string JsonData { get; set; }
public string TransactionID { get; set; }
public string OrderID { get; set; }
public Decimal AmountPaid { get; set; }
}
public class QueryValue
{
public string Name { get; set; }
public string Value { get; set; }
}