Not too long ago I’ve inherited an ASP.NET core utility, which can also be my first time working with the framework. Working with the applying initializing controllers felt very repetitive since all controllers used a couple of widespread companies like loggers. ASP.NET core makes service entry straightforward with dependency injection, but it surely’s difficult to remain true to the DRY precept when each controller is initialized with the identical few companies.
Within the code above, a couple of of the companies being injected are additionally being utilized in different controllers. So, it turns into very repetitive to should initialize all controllers the identical method. However transferring the injection of widespread companies to a base controller won’t work, as seen beneath.
Having the widespread service injected in a base controller constructor will defeat the aim of a base controller and develop into redundant. The companies nonetheless must be outlined in every youngster controller.
Answer
Create Properties As a substitute
What I discovered to work greatest for my wants and the applying is to outline all widespread companies as properties. With ASP.NET Core the Microsoft.Extensions.DependencyInjection identify house offers us entry to the next extension technique HttpContext.RequestServices.GetService<T>.
Warning
With this method, one factor to remember is that it makes use of the HttpContext object, and if it’s not obtainable, you will be unable to make use of the service. And bear in mind the companies nonetheless must be registered within the Startup.cs > ConfigureServices technique.
Base Controller
Baby Controller
Now controllers are solely required to inject the companies particular to them. Thus, sticking to the DRY precept and maintaining the controller constructors clear.
Facet observe, Microsoft appears to choose injection over RequestServices:
The companies obtainable inside an ASP.NET Core request are uncovered by the HttpContext.RequestServices assortment. When companies are requested from within a request, the companies and their dependencies are resolved from the RequestServices assortment.
The framework creates a scope per request and RequestServices exposes the scoped service supplier. All scoped companies are legitimate for so long as the request is energetic.
Be aware: Favor requesting dependencies as constructor parameters to resolving companies from the RequestServices assortment. This ends in courses which can be simpler to check.
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