payment-api

Payment API in Dot Net Core 3

Coding exercise:

Write a WebAPI with only 1 method called “ProcessPayment” that receives a request like this

• CreditCardNumber (mandatory, string, it should be a valid CCN)
• CardHolder: (mandatory, string)
• ExpirationDate (mandatory, DateTime, it cannot be in the past)
• SecurityCode (optional, string, 3 digits)
• Amount (mandatoy decimal, positive amount) Write a Payment domain/entity with the same properties as the request and a second entity to store the payment state (pending, processed, failed). Use Entity framework code first approach, write entity configurations and generate the migrations. The response of this method should be 1 of the followings based on
• Payment is processed: 200 OK
• The request is invalid: 400 bad request
• Any error: 500 internal server error
• The request should be validated before processed. The payment could be processed using different payment providers (external services) called:
• IExpensivePaymentGateway or
• ICheapPaymentGateway. The payment gateway that should be used to process each payment follows the next set of business rules: a) If the amount to be paid is less than £20, use ICheapPaymentGateway. b) If the amount to be paid is £21-500, use IExpensivePaymentGateway if available. Otherwise, retry only once with ICheapPaymentGateway. c) If the amount is > £500, try only PremiumPaymentService and retry up to 3 times in case payment does not get processed d) Store/update the payment and payment state entities created previously once the processing is completed.

Solution

Code covers below concept along with business implementation

• Swagger help API and yaml configuration.
• Automapper & profiles
• NLog
• DotNet DI
• IUnitOfWork & repository pattern.
• NSubstitute and MSUnit Tests
• Entity Framework Core's code first with migrations.
• Fluent API Validation and Entity configuration.

Instruction to run the code

1. Clone the solution: $ git clone https://github.com/nadeemiimt/payment-api.git
2. Open solution in Visual Studio 2019
3. Change web config in /PaymentApi/appsettings.json file and change the DefaultConnection section with correct Database connection string.
4. Build the solution.
5. From Command prompt run below migration commands in root folder:

• dotnet ef --startup-project PaymentApi/PaymentApi.csproj migrations add InitialModel -p PaymentDataLayer/PaymentDataLayer.csproj
  

• dotnet ef --startup-project PaymentApi/PaymentApi.csproj database update
  

6. Verify database is created
7. Run the solution

API Test

• Postman collection: https://github.com/nadeemiimt/payment-api/blob/master/Payment%20API.postman_collection.json has been provided to test API.