At this point, you should be familiar with constructor injection. Nonetheless, next is the controller’s code after migrating the Service Locator pattern to constructor injection: namespace ServiceLocator;public class ConstructorInjectionController : ControllerBase{ private readonly IMyService _myService; public ConstructorInjectionController(IMyService myService) { _myService = myService ??throw new ArgumentNullException(nameof(myService)); } [Route(“/constructor-injection”)] public IActionResult GetUsingConstructorInjection() { _myService.Execute(); return Ok(“Success!”); }} […]
Project – ServiceLocator – Dependency Injection
The best way to avoid something is to know about it, so let’s see how to implement the Service Locator pattern using IServiceProvider to find a dependency.The service we want to use is an implementation of IMyService. Let’s start with the interface: namespace ServiceLocator;public interface IMyService : IDisposable{ void Execute();} The interface inherits from the […]
Understanding the Service Locator pattern – Dependency Injection
Conclusion This section explored replacing the classic Singleton pattern with a standard instantiable class registered with a singleton lifetime. We looked at the old application state, learned that it was no more, and implemented two versions of it. We no longer need that, but it was a good way of learning about singletons.We then implemented […]
First implementation – Dependency Injection
The first implementation uses the memory cache system, and I thought it would be educational to show that to you. Caching data in memory is something you might need to do sooner rather than later. However, we are hiding the cache system behind our implementation, which is also educational.Here is the ApplicationMemoryCache class: public class […]
Revisiting the Singleton pattern – Dependency Injection
The Singleton pattern is obsolete, goes against the SOLID principles, and we replace it with a lifetime, as we’ve already seen. This section explores that lifetime and recreates the good old application state, which is nothing more than a singleton-scoped dictionary.We explore two examples: one about the application state, in case you were wondering where […]
Understanding guard clauses – Dependency Injection
A guard clause represents a condition the code must meet before executing a method. Essentially, it’s a type of code that “guards” against continuing the execution of the method if certain conditions aren’t met.In most cases, guard clauses are implemented at the beginning of a method to throw an exception early when the conditions necessary […]
Use_the_InMemoryLocationService – Dependency Injection
Next, we use the in-memory location service to compose the controller like this: var inMemoryLocationService = new InMemoryLocationService();var devController = new InjectAbstractionLocationsController( inMemoryLocationService); As we can see from the preceding code, we injected a different service into the controller, changing its behavior. This time, after calling the GetAsync method, the controller returned the ten Location […]
Injecting an abstraction in the controller – Dependency Injection
In this last controller, we leverage the SOLID principles, constructor injection, and, inherently, the Strategy pattern to build a controller that we can change from the outside. All we have to do to make the code flexible is inject the interface instead of its implementation, like this: using Microsoft.AspNetCore.Mvc;using Strategy.Services;namespace Strategy.Controllers;[Route(“travel/[controller]”)][ApiController]public class InjectAbstractionLocationsController : ControllerBase{ […]
