The Right Way To Use Scoped Services From Singletons in ASP.NET Core

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Did you ever need to inject a scoped service into a singleton service? I often need to resolve a scoped service, like the EF Core DbContext, in a background service. Another example is when you need to resolve a scoped service in ASP.NET Core middleware. If you ever tried this, you were probably greeted with an exception. In this video, I'll explain how you can solve this problem and safely use scoped services from within singletons in ASP.NET Core.
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Using Scoped Services From Singletons in ASP.NET Core
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Chapters
0:00 Injecting Scoped services in Background jobs
3:07 Resolving Scoped services with IServiceScopeFactory
4:55 IServiceProvider vs IServiceScopeFactory
6:08 Injecting Scoped services in Middleware

[@MilanJovanovicTech]

Get the source code for this video for FREE → the-dotnet-weekly.ck.page/scoped-singleton

[@slvberg]

I just faced this challenge two days ago when implementing hosted services, and was temporarily registering the scoped services as singletons to make it compile. Planned to head back later to deal with it properly. I was immediately interested, and very surprised when I saw your newsletter dropping in my email. Could believe you were watching me. Thank you so much for sharing this!

[@MilanJovanovicTech]

Just happy to help. These are common problems most of us run into (sooner or later)

[@windssoul]

It’s very strange because a few months ago I experienced the same issue when creating an API gateway for our application and had to restructure the dependency injection to handle it with the scoped service factory after trial and error. Then a few weeks later this video pops up lol. So at least I confirm you butt up against this issue almost inevitably.

[@acartunahan]

Thank you Milan. As a junior developer, this video helped me a lot!

[@MilanJovanovicTech]

Glad it helped!

[@Robert-yw5ms]

This also solves a similar issue in blazor server when you want to inject a service that ultimately relies upon dbcontext into a blazor component. The issue being that every socket connection has its own scope that persists as long as the user is connected.

[@MilanJovanovicTech]

Haven't done a lot of Blazor, but I can imagine it's quite similar to how other SPA frameworks treat a "scope"

[@mylesdavies9476]

Useful recap, thanks 🙂

[@MilanJovanovicTech]

Glad it was helpful!

[@10Totti]

Nice tutorial!

[@MilanJovanovicTech]

Thanks!

[@Cornet435]

But what about making middleware with IMiddleware interface nad then register it as a scoped? Then u can inject dbcontext

[@walidchouaib8526]

Thats what i am trying to do to rollback transaction whenever an exception occurred

[@MilanJovanovicTech]

That probably works also (haven't checked, though)

[@primelimitt]

hello great video! I have one question, why does it matter for the db if the scoped instance is different ? I mean we only have 1 db, so it shouldnt matter what is the scope for us. does this work the same with a db that is not in memory? thanks

[@MilanJovanovicTech]

The DbContext will eat up a lot of memory if it's not scoped. Plus there's also the problem of change tracking.

[@usmanali-xz5ub]

How do you learn so many things ? Is there any book ?

[@MilanJovanovicTech]

Solve many problems

[@fataleroro2011]

🎉

[@MilanJovanovicTech]

💪

[@sergeu90]

I don't undertand why we don't see changes in database after SaveChangesAsync when we create scope inside InvokeAsync. Coud you please explain this part on the kzbin.info/www/bejne/fITNdHqaoMeceaMsi=wHhjpr0UgAzO0hFI&t=613 this time. Thanks for video. It is very interesting.

[@MilanJovanovicTech]

It's two different DbContext instances

[@devliren]

:)

[@MilanJovanovicTech]

😁😁