In this post, we are going to write about what we consider to be the best practices while developing the .NET Core Web API project. How we can make it better and how to make it more maintainable.
We are going to go through the following sections:
In this post, we are going to write about what we consider to be the best practices while developing the .NET Core Web API project. How we can make it better and how to make it more maintainable.
We are going to go through the following sections:
namespace Loans.Entities { public class Applicant { public int Id { set; get; } public string Name { set; get; } public int Age { set; get; } public string Address { set; get; } public decimal Salary { set; get; } } }
namespace Loans.Entities { public class LoanProduct { public int Id { set; get; } public string ProductName { set; get; } public decimal InterestRate { set; get; } } }
namespace Loans.Entities { public class LoanApplication { public int Id { set; get; } public LoanProduct Product { set; get; } public LoanAmount Amount { set; get; } public Applicant Applicant { set; get; } public bool IsAccepted { set; get; } } public class LoanAmount { public string CurrencyCode { get; set; } public decimal Principal { get; set; } } }
namespace Loans.Models { public class IdentityVerificationStatus { public bool Passed { get; set; } } }
using Loans.Models; namespace Loans.Services.Contracts { public interface IIdentityVerifier { void Initialize(); bool Validate(string applicantName, int applicantAge, string applicantAddress); void Validate(string applicantName, int applicantAge, string applicantAddress, out bool isValid); void Validate(string applicantName, int applicantAge, string applicantAddress, ref IdentityVerificationStatus status); } }
namespace Loans.Services.Contracts { public interface ICreditScorer { int Score { get; } void CalculateScore(string applicantName, string applicantAddress); } }
using System; using Loans.Entities; using Loans.Services.Contracts; namespace Loans.Services { public class LoanApplicationProcessor { private const decimal MinimumSalary = 1_500_000_0; private const int MinimumAge = 18; private const int MinimumCreditScore = 100_000; private readonly IIdentityVerifier _identityVerifier; private readonly ICreditScorer _creditScorer; public LoanApplicationProcessor( IIdentityVerifier identityVerifier, ICreditScorer creditScorer) { _identityVerifier = identityVerifier ?? throw new ArgumentNullException(nameof(identityVerifier)); _creditScorer = creditScorer ?? throw new ArgumentNullException(nameof(creditScorer)); } public bool Process(LoanApplication application) { application.IsAccepted = false; if (application.Applicant.Salary < MinimumSalary) { return application.IsAccepted; } if (application.Applicant.Age < MinimumAge) { return application.IsAccepted; } _identityVerifier.Initialize(); var isValidIdentity = _identityVerifier.Validate( application.Applicant.Name, application.Applicant.Age, application.Applicant.Address); if (!isValidIdentity) { return application.IsAccepted; } _creditScorer.CalculateScore(application.Applicant.Name, application.Applicant.Address); if (_creditScorer.Score < MinimumCreditScore) { return application.IsAccepted; } application.IsAccepted = true; return application.IsAccepted; } } }
using System; using Loans.Models; using Loans.Services.Contracts; namespace Loans.Services { public class IdentityVerifierServiceGateway : IIdentityVerifier { public DateTime LastCheckTime { get; private set; } public void Initialize() { // Initialize connection to external service } public bool Validate(string applicantName, int applicantAge, string applicantAddress) { Connect(); var isValidIdentity = CallService(applicantName, applicantAge, applicantAddress); LastCheckTime = DateTime.Now; Disconnect(); return isValidIdentity; } private void Connect() { // Open connection to external service } private bool CallService(string applicantName, int applicantAge, string applicantAddress) { // Make call to external service, interpret the response, and return result return false; // Simulate result for demo purposes } private void Disconnect() { // Close connection to external service } public void Validate(string applicantName, int applicantAge, string applicantAddress, out bool isValid) { throw new NotImplementedException(); } public void Validate(string applicantName, int applicantAge, string applicantAddress, ref IdentityVerificationStatus status) { throw new NotImplementedException(); } } }
public LoanApplicationProcessor( IIdentityVerifier identityVerifier, ICreditScorer creditScorer) { _identityVerifier = identityVerifier ?? throw new ArgumentNullException(nameof(identityVerifier)); _creditScorer = creditScorer ?? throw new ArgumentNullException(nameof(creditScorer)); }
<Project Sdk="Microsoft.NET.Sdk"> <PropertyGroup> <TargetFramework>netcoreapp2.2</TargetFramework> </PropertyGroup> <ItemGroup> <ProjectReference Include="..\Loans\Loans.csproj" /> </ItemGroup> <ItemGroup> <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.3.0" /> <PackageReference Include="MSTest.TestAdapter" Version="2.0.0" /> <PackageReference Include="MSTest.TestFramework" Version="2.0.0" /> </ItemGroup> </Project>
using Loans.Entities; using Loans.Services; using Microsoft.VisualStudio.TestTools.UnitTesting; namespace Loans.Tests { [TestClass] public class LoanApplicationProcessorShould { [TestMethod] public void DeclineLowSalary() { var product = new LoanProduct {Id = 99, ProductName = "Loan", InterestRate = 5.25m}; var amount = new LoanAmount {CurrencyCode = "Rial", Principal = 2_000_000_0}; var applicant = new Applicant {Id = 1, Name = "User 1", Age = 25, Address = "This place", Salary = 1_100_000_0}; var application = new LoanApplication {Id = 42, Product = product, Amount = amount, Applicant = applicant}; var processor = new LoanApplicationProcessor(null, null); processor.Process(application); Assert.IsFalse(application.IsAccepted); } } }
public class LoanApplicationProcessor { private const decimal MinimumSalary = 1_500_000_0;
Test method Loans.Tests.LoanApplicationProcessorShould.DeclineLowSalary threw exception: System.ArgumentNullException: Value cannot be null. Parameter name: identityVerifier
public LoanApplicationProcessor( IIdentityVerifier identityVerifier, ICreditScorer creditScorer) { _identityVerifier = identityVerifier ?? throw new ArgumentNullException(nameof(identityVerifier)); _creditScorer = creditScorer ?? throw new ArgumentNullException(nameof(creditScorer)); }
> dotnet add package Moq > Install-Package Moq
using Loans.Entities; using Loans.Services; using Loans.Services.Contracts; using Microsoft.VisualStudio.TestTools.UnitTesting; using Moq; namespace Loans.Tests { [TestClass] public class LoanApplicationProcessorShould { [TestMethod] public void DeclineLowSalary() { var product = new LoanProduct {Id = 99, ProductName = "Loan", InterestRate = 5.25m}; var amount = new LoanAmount {CurrencyCode = "Rial", Principal = 2_000_000_0}; var applicant = new Applicant {Id = 1, Name = "User 1", Age = 25, Address = "This place", Salary = 1_100_000_0}; var application = new LoanApplication {Id = 42, Product = product, Amount = amount, Applicant = applicant}; var mockIdentityVerifier = new Mock<IIdentityVerifier>(); var mockCreditScorer = new Mock<ICreditScorer>(); var processor = new LoanApplicationProcessor(mockIdentityVerifier.Object, mockCreditScorer.Object); processor.Process(application); Assert.IsFalse(application.IsAccepted); } } }
using Loans.Entities; using Loans.Services; using Loans.Services.Contracts; using Microsoft.VisualStudio.TestTools.UnitTesting; using Moq; namespace Loans.Tests { [TestClass] public class LoanApplicationProcessorShould { [TestMethod] public void Accept() { var product = new LoanProduct {Id = 99, ProductName = "Loan", InterestRate = 5.25m}; var amount = new LoanAmount {CurrencyCode = "Rial", Principal = 2_000_000_0}; var applicant = new Applicant {Id = 1, Name = "User 1", Age = 25, Address = "This place", Salary = 1_500_000_0}; var application = new LoanApplication {Id = 42, Product = product, Amount = amount, Applicant = applicant}; var mockIdentityVerifier = new Mock<IIdentityVerifier>(); var mockCreditScorer = new Mock<ICreditScorer>(); var processor = new LoanApplicationProcessor(mockIdentityVerifier.Object, mockCreditScorer.Object); processor.Process(application); Assert.IsTrue(application.IsAccepted); } } }
_identityVerifier.Initialize(); var isValidIdentity = _identityVerifier.Validate( application.Applicant.Name, application.Applicant.Age, application.Applicant.Address);
namespace Core1RtmEmptyTest.Services { public interface IMessagesService { string GetSiteName(); } public class MessagesService : IMessagesService { public string GetSiteName() { return "DNT"; } } }
{ "dependencies": { // same as before "Core1RtmEmptyTest.Services": "1.0.0-*" },
public void Configure( IApplicationBuilder app, IHostingEnvironment env, IMessagesService messagesService)
public void Configure( IApplicationBuilder app, IHostingEnvironment env, IMessagesService messagesService) { app.Run(async context => { var siteName = messagesService.GetSiteName(); await context.Response.WriteAsync($"Hello {siteName}"); }); }
System.InvalidOperationException No service for type 'Core1RtmEmptyTest.Services.IMessagesService' has been registered. at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType) at Microsoft.AspNetCore.Hosting.Internal.ConfigureBuilder.Invoke(object instance, IApplicationBuilder builder) System.Exception Could not resolve a service of type 'Core1RtmEmptyTest.Services.IMessagesService' for the parameter 'messagesService' of method 'Configure' on type 'Core1RtmEmptyTest.Startup'. at Microsoft.AspNetCore.Hosting.Internal.ConfigureBuilder.Invoke(object instance, IApplicationBuilder builder) at Microsoft.AspNetCore.Hosting.Internal.WebHost.BuildApplication()
public class Startup { public void ConfigureServices(IServiceCollection services) { services.AddTransient<IMessagesService, MessagesService>(); }
{ "dependencies": { // same as before "StructureMap.Dnx": "0.5.1-rc2-final" },
public class Startup { public IServiceProvider ConfigureServices(IServiceCollection services) { services.AddDirectoryBrowser(); var container = new Container(); container.Configure(config => { config.Scan(_ => { _.AssemblyContainingType<IMessagesService>(); _.WithDefaultConventions(); }); //config.For<IMessagesService>().Use<MessagesService>(); config.Populate(services); }); container.Populate(services); return container.GetInstance<IServiceProvider>(); }