kotlinlang #android-architecture

Hey everyone! Still trying to get the hang of MVVM here I’m having some issues with handling events from the view Let’s say I have a view where I can create a new flower. When I click “Add” i want my flower to be saved to my repository I’m currently calling a

saveFlower(flowerData:FlowerData)

method in my viewModel from my Fragment and passing it all the fields values. The ViewModel that holds my FlowerRepository is then creating the proper Flower object and saving to the FlowerRepository This feels wrong to have the ViewModel both presenting data and handling it, what should I do?

ursus

05/22/2020, 7:48 AM

How do you test repositories which touch network inside? mockwebserver+json files?

ursus

05/24/2020, 12:15 PM

Given the fakes vs mocks debate, if you were to chose fakes, that means mostly that only db and network needs to be faked, all their dependants can be real

ursus

05/24/2020, 12:16 PM

so...Dagger in unit tests, and just swap out db provider maybe?

ursus

05/24/2020, 12:17 PM

what was even the issue people had against it?

Rahul Ch

05/24/2020, 5:44 PM

I created my own android ribs architecture, which would help to create a super app/full modular app https://github.com/Bender-Story/android-modular-app-ribs

💯 1

nino

05/26/2020, 10:33 AM

Can someone tell me how I can prevent creating an AbstractActivity or BaseActivity in a new project and still be able to do some customizations for all activities inside the app? E.g. setting up a custom toolbar… What’s the best approach for that?

ursus

05/27/2020, 2:19 AM

Is repositories depending on repositories a bad idea down the line?

ursus

05/28/2020, 1:56 PM

IOfferManager+OfferManager OfferManager+OfferManagerImpl OfferManafer+ImplOfferManager OfferManager+RealOfferManager

rkeazor

05/28/2020, 4:52 PM

In traditional MVVM, what do you guys consider your model(ie your networking layer) ?

ursus

06/13/2020, 11:20 PM

fun <T> body(response: Response<T>): T? {
        return if (!response.isSuccessful) {
            val errorResponse = try {
                val errorBody = response.errorBody()
                if (errorBody != null) {
                    moshi.adapter(ErrorResponse::class.java).fromJson(errorBody.source())
                } else {
                    null
                }
            } catch (ex: Exception) {
                null
            }
            val retryAfterTimestampMillis = errorResponse
                ?.error
                ?.retryAfter
                ?.let(TimestampParserHelper::parseTimestampMillis)

            throw ApiException(
                path = response.raw().request.url.encodedPath,
                errorCode = response.code(),
                errorMessage = errorResponse?.error?.errorMessage,
                retryAfterTimestamp = retryAfterTimestampMillis
            )
        } else {
            response.body()
        }
    }

ursus

06/13/2020, 11:21 PM

I have code like this to unwrap Single<Response<T>> and throw my ApiException if needed

ursus

06/13/2020, 11:21 PM

can retrofit make this go away some way smart? or okhttp interceptor?

ursus

06/16/2020, 7:08 PM

How do you guys prefix your or postfix your rest stuff (retrofit interface + models)?

PaymentApi? PaymentService?

ApiCreditCard? ServiceCreditCard? RemoteCreditCard?

Steve

06/16/2020, 9:11 PM

how does one generally expose an app configuration to the rest of the app? Specifically, I do need part of it for my network requests, as the config is what provides the keys

mattinger

06/18/2020, 6:29 PM

Anyone know how to react to returning from a navigation subgraph? I basically want to treat the subgraph as a black box and re-use it in several different other graphs. The problem is how do i detect when i’ve come back from it. I could use a destination listener, and add it prior to navigation, and remove it when it comes back to the destination i want, but that doesn’t work right if the app goes out of memory and is rebuilt.

06/30/2020, 1:37 AM

Hello everyone, question about the MVI /MVVM architecture, I was wondering how folks handle navigation events / one shot events like showing a snack bar, navigating to a different fragment/activity, showing a dialog etc in their MVI/MVVM architecture. I know there's a SingleLiveEvent class created in a Google example repo, I've seen the Event wrapper solutions. But all of these are sort of workarounds. - The SingleLiveEvent option ties you to the MutableLiveData API and if that changes, your implementation breaks. Unless you create your own version that favors composition I suppose. -Using the Event wrapper to check if the value has been handled previously works, but brings about a redundant object wrapper and still doesn't fit with MVI/MVVM pattern of emitting a single state from your VM or w/e Is the only realistic approach to handling these one shot events as a separate thing from the "view state" that gets emitted in both MVI/MVVM patterns? Whats everyones thoughts?

dewildte

06/30/2020, 7:58 PM

We need a google backed solution for this ☝️. Maybe a really good blog article (Not the

SingleLiveEvent

anti pattern post.) or some sort of AA Component. Kotlin

Flow

Channel

is good for this but it seems like that is not common knowledge.

Hakob Astvacatryan

07/07/2020, 8:27 PM

Hi guys, I’m using koin for di, I made mistake and put root activity’s viewmodel to activity scope and now viewmodel doesn’t get retained after rotation. The problem I needed to solve by putting viewmodel into activity scope is to allow child viewmodels inject root activity’s viewmodel. Is there way to do that and retain view model?

Slackbot

07/10/2020, 7:56 AM

This message was deleted.

ursus

07/16/2020, 4:17 AM

in dagger, can a module say "single instance per whatever component this module gets attached to,"?

ursus

07/18/2020, 12:50 PM

Is creating multiple Retrofit service instances okay? One per module; lets say 20 overall; given the okhttp instance is shared? Or should I rather strive for a single big retrofit instance and have it extend some partial interfaces, so it then can get injected behind it?

Joost Klitsie

07/19/2020, 8:29 AM

Hi all, I was wondering about something: If I use UseCases to do things in my app, and I have lets say a screen and I can load an item, lets say a user account, into the screen using the id of the user. I would like to observe the user by its id from the current value in the repository, and of course any changes in the user will be propagated in my flow. So I have a ObserveUserUseCase to handle this for me. My question: If lets say this user is not existing yet in my repository and I need to fetch it from the backend, would you put that logic into the a) The ObserveUserUseCase (if the repository returns null/not existing it fetches the user) b) In the repository, observing on the user might trigger a backend call in this case automatically c) Make the ObserveUserUseCase return something to show its not existing in the repository (like NullPointer) to my ViewModel and call a separate FetchUserUseCase to load the user

ursus

07/27/2020, 5:17 PM

why not split it into

:payments

:payments-ui

07/30/2020, 6:48 PM

Hello everyone, I'm just looking for a architecture or dessign patterns to handle app based on roles or permissions. For example, I have four different user types, and I want to handle some features enabled for two users and disababled by default. I read something about feature toggle, but I'm not sure if is the best option, because I want to avoid if statements checks in the code. Someone know something about this? Thanks!! 🙂

Vincent Williams

08/06/2020, 2:43 AM

when using sealed classes for the viewstate in android, how do you handle updating part of the viewstate? For example:

sealed class ViewState {
    object Idle : ViewState()
    data class Content(
        val headerText: String,
        val bodyText: String
    ) : ViewState()
    data class Error(
        val message: String
    ) : ViewState
}

How do I update just the title for example? I see a lot of examples use sealed classes but they dont seem so great in practice...

ursus

08/14/2020, 3:56 AM

Hey, I notice update to preferences take around 0-1ms, how is this possible with disc io? If it only updates some memcache, which is only later synchronized to disc async-ly; does it mean its not as durable as a sqlite would?

Fanilog

08/18/2020, 9:03 AM

Hello all, I’ve a question/debate around clean architecture. 👋 I’m working on a project that follows the clean architecture principles. From https://blog.cleancoder.com/=> “_Typically the data that crosses the boundaries is simple data structures. You can use basic structs or simple Data Transfer objects if you like. Or the data can simply be arguments in function calls. Or you can pack it into a hashmap, or construct it into an object. The important thing is that isolated, simple, data structures are passed across the boundaries. We don’t want to cheat and pass Entities or Database rows. We don’t want the data structures to have any kind of dependency that violates The Dependency Rule._” We can see a lot of example in the web returning

Flow<data>

from the Service layer to their Repository and Interactor. I was wondering if doing this way it’s breaking one the principles by having a strong dependency with the current implementation of the Flow (external service)?

ursus

08/18/2020, 8:24 PM

Testing people who use fakes. Do you fake all the layers only the "edge" ones like db or api? Since I want to test a viewmodel now, and then have to recreate the whole stack just to swap the fake api at the end, and its so stupid, so much code Why not just mockito stub out the direct view model dependencies?

👍 1

Raj Trivedi

08/21/2020, 10:57 AM

We have an app right now..and want to move towards sdk so that our clients can easily use our services..do we have any sources on what architecture to follow for an android mobile sdk? I have clean architecture in mind..any suggestions?

👍 1

Title

Raj Trivedi

08/21/2020, 10:57 AM

👍 1

Susheel

08/21/2020, 4:36 PM

Following this thread.

John Leeroy

08/21/2020, 5:43 PM

Look into domain-driven design and think of your code/technology as a domain. My favorite qualities of SDKs or libraries is the focus on simple interfaces and data models that are exposed.

❤️ 1

Look into Retrofit and how they achieved configurability and extensibility. Examples are how they support several json serializer like Moshi, Gson, Jackson, etc. They also support coroutines, Rx, etc through extension modules. Maybe your product have the opportunity to make integration easier.

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