C#•12mo ago

✅ What is the purpose of `[FromServices]`

Aren't dependencies already being injected from the services registered?

4 Replies

cap5lut•12mo ago

ASP.NET Core has built-in support for dependency injection. You can use dependency injection in ASP.NET Core to plug in components at runtime, making your code more flexible and easier to test and maintain. There are three basic ways to inject dependencies, namely constructor injection, setter injection, and interface injection. Constructor injection may be the most widely used way to inject dependencies in ASP.NET Core. However, constructor injection is not always an ideal choice, especially when you need dependencies in just one or a handful of methods. In such cases, it’s more efficient to take advantage of the FromServices attribute, which allows you to inject dependencies directly into the action methods of your controller.

(https://www.infoworld.com/article/3451821/how-to-use-the-fromservices-attribute-in-aspnet-core.html)

mindhardt•12mo ago

You need some place to inject into. Usually you do it via private readonly fields in your class that are set in constructor

public class CacheService
{
    private readonly IMemoryCache _memoryCache;

    public CacheService(IMemoryCache memoryCache)
    {
        _memoryCache = memoryCache;
    }
}

public class CacheService
{
    private readonly IMemoryCache _memoryCache;

    public CacheService(IMemoryCache memoryCache)
    {
        _memoryCache = memoryCache;
    }
}

But with controllers you can inject services directly in your methods via [FromServices]

Unknown User•12mo ago

Message Not Public

Thinker•12mo ago

(or in minimal API endpoints catcorn

Gaming

Programming

✅ What is the purpose of `[FromServices]`