如何在Asp.Net Core DI上注入具有不同生命周期的同一个类？

Question

In the past, I used Unity Container to resolve my dependencies with Asp.Net MVC. Now I am planning to use the Asp.Net Core DI instead of Unity that doesn't have at the moment a viable way to integrate with Core, and I am trying to figure out which is the best way to inject the same class but with different life cycles.

Why? My question itself is coming because more than one thread operating on a single Entity Framework context was not thread safe and in order to execute a separate query in another thread I need a separate instance of my DbContext for each thread instance. My strategy with Unity was creating 2 UnityContainers, one that had all singleton classes and the other that was creating the instances per request. So when I created the second query in a separate thread I just resolve it through the unity's instance created per request.

With Asp.Net Core I would like to know:

1- Which is the best way to solve my problem?

2- If I choose the same strategy I would like to know how can I have the same Asp.Net Core DI twice?, maybe applying a CompositionRoot pattern to both "containers"

3-If I don't choose my strategy, which pattern I can use to resolve in the same container an instance of the same class with different life cycles, and which is the way to resolve them separately?

Answer 1

What you're asking for is unnecessary, really.

When you add a DbContext in the ConfigureServices (using the services.AddDbContext<MyDbContext> extension method) method in the StartUp class of an ASP .NET Core application, by default is gets registered as with a scoped lifetime. The scoped lifetime is required to get around the thread safety issue you mention.

Of course, you can override this with AddDbContext by passing some additional parameters. Or, you can register the context yourself. But, why would you want to(?).