How scope a database to a logged in user using Hil...

# dagger

[André Thiele]

How scope a database to a logged in user using Hilt? The problem is that a database should also be kind of singleton scoped but also scoped to a new user when logging out and in.

[Colton Idle]

Scopes used to confuse me a lot and I think Jake explained it well once, but basically... Only you know the lifetime of a scope such as "UserLoggedIn" and so if you just create a new scope, then instantiate it when the user is logged, then get rid of it on log out, and that should be what you need.

Just a heads up that I've never created a custom scope actually, but I read into it a lot when I tried doing the same thing that you're doing. I wanted a UserLoggedIn scope and UserLoggedOut scope but a few different questions online ended up talking me out if it. I think Uber had done this in their RIBS architecture.

[André Thiele]

Yeah I'm experiencing the same. I can't even find proper samples and this is a common problem in a real world application

[André Thiele]

Currently building a custom component

[Jason Ankers]

Hey I recently implemented an AuthenticatedScope with dagger. If you’re using Hilt a great starting point is https://medium.com/androiddevelopers/hilt-adding-components-to-the-hierarchy-96f207d6d92d

[André Thiele]

Yes I am referring to this right now, but i just learned that WorkManager cant access dependencies of custom components

[André Thiele]

sooo i dont really know what I should do now

[André Thiele]

@Jason Ankers would you mind sending me a gist of it?

[Jason Ankers]

@exfalso What is it in particular you aren’t sure about? It’s basically the same as the article but I added some extension functions to make injecting less verbose

[Jason Ankers]

Dont use WorkManager so unfortunately cant offer much help there

[André Thiele]

yea i was just wondering because if i build a AuthComponent with my DB, then every other dependency would have to get manually injected using EntryPoints and this would be super messy

[André Thiele]

because all repositories access the db and would have to be scoped to the same component

[Jason Ankers]

Yeah most of our repositories are auth scoped as well. I made them extension properties on the component, so injecting looks like:

private val userRepository = authManager.component.userRepository

[Jason Ankers]

No idea if this is the right thing to do or not, I asked about it here https://kotlinlang.slack.com/archives/C5FT9Q36G/p1615776557029500

[André Thiele]

mhmm

[André Thiele]

i would need to replace constructor injection everywhere

[André Thiele]

just for one db that should be scoped

[André Thiele]

seems weird to me

[André Thiele]

also, work manager needs to access the dependencies of the custom components which is not possible as far as i know

[Jason Ankers]

Can you not constructor inject your auth manager into work manager?

[André Thiele]

WorkManager would need to be SingletonScoped so the scopes would clash

[Jason Ankers]

What scope does it have

[André Thiele]

I think WorkManager has to be Singleton, and my repositories would be scoped to AuthComponent which is technically one layer below Singleton so the dependency is not available to the WorkManager

[André Thiele]

"You can use only @Singleton or unscoped bindings in Worker objects. You must also annotate the Context and WorkerParameters dependencies with `@Assisted`:"

[André Thiele]

@Jason Ankers do you know if its possible to remove it from the constructor injection and inject it using your extension?

[André Thiele]

This is how i did it: https://stackoverflow.com/a/66941259/10319730

[Carl Benson]

amazing, I had exact this problem last week but decided to implement explicit database closing when logging out. This is much nicer, will adopt 🙏