How to use keyed services in ASP.NET Core

"Dependency injection (also known as DI) is a design pattern in which the dependent types of a class are injected (passed to it by another class or object) rather than created directly, thereby facilitating loose coupling and promoting easier testing and maintenance. In ASP.NET Core, both framework services and application services can be injected into your classes, rather than being tightly coupled. In this article, we'll examine how we can work with keyed services to simplify dependency injection in ASP.NET Core."

"Launch the Visual Studio 2022 IDE. Click on "Create new project." In the "Create new project" window, select "ASP.NET Core Web API" from the list of templates displayed. Click "Next." In the "Configure your new project" window, specify the name and location for the new project. Optionally check the "Place solution and project in the same directory" check box, depending on your preferences. Click "Next." In the "Additional Information" window shown next, select ".NET 9.0 (Standard Term Support)" as the framework version and uncheck the check box that says "Use controllers." We'll be using minimal APIs in this project."

Dependency injection injects dependent types into a class rather than creating them directly, enabling loose coupling and easier testing. ASP.NET Core supports injecting both framework and application services into classes to avoid tight coupling. Keyed services enable selecting a specific service implementation at runtime, simplifying scenarios where multiple implementations exist. Visual Studio 2022 is required to run the provided code examples. Creating an ASP.NET Core Web API project with minimal APIs and .NET 9.0 sets up the environment for implementing keyed dependency injection patterns.

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