ASP.NET Core is designed from the ground up to support the dependency injection design pattern. Dependency injection in ASP.NET Core provides a technique to create applications that are loosely coupled. ASP.NET Core allows us to injects dependent objects either through constructor or methods. Based on the environment in which application is running different objects can be injected.

What is Dependency Injection?

Dependency injection is used to achieve loose coupling in application between client objects and their dependencies. Instead of directly instantiating objects of classes and using them rather Interfaces are used and objects are provided to class in some way either through constructor or through some method.

Class will depend on an interface rather than concrete implementation of dependencies. This makes our code loosely coupled as we can inject any concrete object as far as it implements the required interface.

ASP.NET Core comes with a built-in container (IServiceProvider) that supports constructor injection by default and the framework itself provides some services through dependency injection.

Why Dependency Injection

• Improves code readability by keeping it clean so easier to maintain it.
• Application is loosely coupled which improves flexibility
• Increases code testing ability with different mock implementations of services.
• Supports extendable class structure

Implementation of Dependency Injection in ASP.NET Core

There are two types of services in ASP.NET Core

1. Framework provided services – These services are part of ASP.NET Core framework
2. Custom Services – These are add-on services created by developers

Registering framework provided services

Below code shows how to register a framework defined service (Memory Caching Service) in ConfigureServices() method of startup.cs

public class Startup
{
    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllersWithViews();
        services.AddMemoryCache();
    }
    //Remaining code was removed
}

#programming #.net core #asp.net core 3.1 #dependency injection #object oriented concepts