How to Integrate ASP.NET MVC Application with Paypal

4. Once your account is created, click on the gear icon (for setting up the payment gateway). Click on Business Setup

5. Click on My Apps & credential menu and then click on create an App.

6. Provide App Name and Sandbox developer account in order to create App.

7. If you don’t have Sandbox account, you have to click on Account menu under the sandbox section. For the Testing purpose, we need two accounts: One is Business and another is Merchant account.

8. Now, click on the App Name created in the previous step in order to get ClientID and Secret key (for the sandbox as well as live). We will use the sandbox ClientID as well as the Secret key for testing purpose.

9. Let’s create a new empty MVC Project and install the PayPal library reference from the nugget package manager.

10. You can also visit http://paypal.github.io/PayPal-NET-SDK/ for the supporting documents, samples, codebase.

11. Add below code in the configuration section of web.config in order to configure the PayPal.

<configSections>
    <section name="paypal" type="PayPal.SDKConfigHandler, PayPal" />
  </configSections>
  <!-- PayPal SDK settings -->
  <paypal>
    <settings>
      <add name="mode" value="sandbox" />
      <add name="connectionTimeout" value="360000" />
      <add name="requestRetries" value="1" />
      <add name="clientId" value="Add-Your-ClientID-Here" />
      <add name="clientSecret" value="Add-Your-ClientSecret-Key-Here" />
    </settings>
  </paypal>

publicstaticclassPaypalConfiguration
    {
//Variables for storing the clientID and clientSecret key
publicreadonlystaticstring ClientId;
publicreadonlystaticstring ClientSecret;
//Constructor
static PaypalConfiguration()
        {
var config = GetConfig();
            ClientId = config["clientId"];
            ClientSecret = config["clientSecret"];
        }
// getting properties from the web.config
publicstatic Dictionary<string, string> GetConfig()
        {
return PayPal.Api.ConfigManager.Instance.GetProperties();
        }
privatestaticstring GetAccessToken()
        {
// getting accesstocken from paypal               
string accessToken = new OAuthTokenCredential
        (ClientId, ClientSecret, GetConfig()).GetAccessToken();
return accessToken;
        }
publicstatic APIContext GetAPIContext()
        {
// return apicontext object by invoking it with the accesstoken
            APIContext apiContext = new APIContext(GetAccessToken());
            apiContext.Config = GetConfig();
return apiContext;
        }
    }

13. Now add an action method named it as PaymentWithPaypal which will be used for redirecting to PayPal payment gateway and for executing the transaction. Basically PaymentWithPaypal action redirect used to the PayPal’s payment page and once user click on pay, it will provide Payer ID which will be used for executing the transaction.

public ActionResult PaymentWithPaypal(string Cancel = null)
        {
//getting the apiContext
            APIContext apiContext = PaypalConfiguration.GetAPIContext();
try
            {
//A resource representing a Payer that funds a payment Payment Method as paypal
//Payer Id will be returned when payment proceeds or click to pay
string payerId = Request.Params["PayerID"];
if (string.IsNullOrEmpty(payerId))
                {
//this section will be executed first because PayerID doesn't exist
//it is returned by the create function call of the payment class
// Creating a payment
// baseURL is the url on which paypal sendsback the data.
string baseURI = Request.Url.Scheme + "://" + Request.Url.Authority +
"/Home/PaymentWithPayPal?";
//here we are generating guid for storing the paymentID received in session
//which will be used in the payment execution
var guid = Convert.ToString((new Random()).Next(100000));
//CreatePayment function gives us the payment approval url
//on which payer is redirected for paypal account payment
var createdPayment = this.CreatePayment(apiContext, baseURI + "guid=" + guid);
//get links returned from paypal in response to Create function call
var links = createdPayment.links.GetEnumerator();
string paypalRedirectUrl = null;
while (links.MoveNext())
                    {
                        Links lnk = links.Current;
if (lnk.rel.ToLower().Trim().Equals("approval_url"))
                        {
//saving the payapalredirect URL to which user will be redirected for payment
                            paypalRedirectUrl = lnk.href;
                        }
                    }
// saving the paymentID in the key guid
                    Session.Add(guid, createdPayment.id);
return Redirect(paypalRedirectUrl);
                }
else
                {
// This function exectues after receving all parameters for the payment
var guid = Request.Params["guid"];
var executedPayment = ExecutePayment(apiContext, payerId, Session[guid] asstring);
//If executed payment failed then we will show payment failure message to user
if (executedPayment.state.ToLower() != "approved")
                    {
return View("FailureView");
                    }
                }
            }
catch (Exception ex)
            {
return View("FailureView");
            }
//on successful payment, show success page to user.
return View("SuccessView");
        }
private PayPal.Api.Payment payment;
private Payment ExecutePayment(APIContext apiContext, string payerId, string paymentId)
        {
var paymentExecution = new PaymentExecution() { payer_id = payerId };
this.payment = new Payment() { id = paymentId };
returnthis.payment.Execute(apiContext, paymentExecution);
        }
private Payment CreatePayment(APIContext apiContext, string redirectUrl)
        {
//create itemlist and add item objects to it
var itemList = new ItemList() { items = new List<Item>() };
//Adding Item Details like name, currency, price etc
            itemList.items.Add(new Item()
            {
                name = "Item Name comes here",
                currency = "USD",
                price = "1",
                quantity = "1",
                sku = "sku"
            });
var payer = new Payer() { payment_method = "paypal" };
// Configure Redirect Urls here with RedirectUrls object
var redirUrls = new RedirectUrls()
            {
                cancel_url = redirectUrl + "&Cancel=true",
                return_url = redirectUrl
            };
// Adding Tax, shipping and Subtotal details
var details = new Details()
            {
                tax = "1",
                shipping = "1",
                subtotal = "1"
            };
//Final amount with details
var amount = new Amount()
            {
                currency = "USD",
                total = "3", // Total must be equal to sum of tax, shipping and subtotal.
                details = details
            };
var transactionList = new List<Transaction>();
// Adding description about the transaction
            transactionList.Add(new Transaction()
            {
                description = "Transaction description",
                invoice_number = "your generated invoice number", //Generate an Invoice No
                amount = amount,
                item_list = itemList
            });
this.payment = new Payment()
            {
                intent = "sale",
                payer = payer,
                transactions = transactionList,
                redirect_urls = redirUrls
            };
// Create a payment using a APIContext
returnthis.payment.Create(apiContext);
        }

14. Now build and call PaymentWithPaypal action of Home controller. You will be redirected to the sandbox payment page of PayPal. Login here with the Business account created on sandbox in earlier steps.

15. On expanding the Amount, you will see the details like description, items, subtotal, shipping charges, VAT etc. applied to the transaction. Click on Login.

16. Click on Continue in order to pay the amount.

17. You will get payment successful message or payment failed in case of exception as the final result of the completion of the transaction.

18. You can also check notification for the payment made under the sandbox account by expanding and clicking on notification link.