I ve read a lot about state managment and libraries that hel

Question

I ve read a lot about state managment and libraries that help like redux flowredux decompose kotlin bloc etc But I can t seem to wrap my head around how composables are meant to relate to state and the one that seems to have the proper example decompose just seems overly complicated Searching google is a crap shoot since jetpack is so popular I m primarily developing a desktop app but the state is rather complicated so I m concerned about state mgmt using just compose What s the secret recipe that I am missing for someone relativly green

Casey Brooks · Answer

To clear things up Decompose is not a state management library It s a routing library that happens to be able to restore state between sessions routes like `SavedStateHandle` on Android But it is not intended to be used as a State Management layer like Redux I ve shared a snippet here before of an example of custom State Management in Compose Desktop for a basic idea of how it all works from a centralized ViewModel type pattern And finally I haven t shared it publicly yet but I m getting very close to releasing a new library for State Management which works on Compose Desktop You can though there s not much documentation yet

Big Chungus · Answer

Here s redux usage example <https github com mpetuska kamp blob feature compose app client src commonMain kotlin util redux compose kt|https github com mpetuska kamp blob feature compose app client src commonMain kotlin util redux compose kt>

Jasin Colegrove · Answer

thank you both < Casey Brooks> very well documented mental model Good reading

rocketraman · Answer

< Casey Brooks> Looks like a very nice project Do you plan to make ballast work on compose web JS target as well

KamilH · Answer

Have you seen MVIKotlin <https github com arkivanov MVIKotlin>

Humphrey · Answer

I m also struggling with the state management I ll look into these links later on Thanks for sharing

Casey Brooks · Answer

Ballast intentionally doesn t bind itself to any particular UI views I ve been using it on Desktop and Android for a while and it s currently compiled for JS and should work there but I haven t actually run it in JS yet

Casey Brooks · Answer

The other KMP MVI library I m aware of is which is more mature That team put together a walking one through the steps to get to MVI to help you understand how to use the pattern I m also putting together a between all these libraries While I am trying to be objective and highlight where each library works best I m sure I ve got blind spots and would appreciate any changes suggestions to the table

Jasin Colegrove · Answer

< Casey Brooks> One thing I am still stuck on what is the purpose of the ViewModel if the State is held in the Contract Or is State supposed to be in my viewmodel and not the contract

Jasin Colegrove · Answer

I think I am conflating the two well three the trivial example the mental model and the Sample I probably just answered my own question

Casey Brooks · Answer

Yeah this is why I have t fully released it yet documentation is very much needed blush But don t worry I m working hard on getting this done soon You can see a mostly complete example in with the actual connection from the ViewModel to Compose The idea is that the `Contract` is just that a contract It doesn t do anything by itself it s just a declarative model of your the data and interactions of a screen as a bunch of classes The ViewModel and it s related components are what actually implement the MVI pattern the ViewModel holds onto the State object as a StateFlow and processes the Inputs as they are sent to the ViewModel

Jasin Colegrove · Answer

no worries this is just so much different to what I am used to that i need to recompose my thought process

Casey Brooks · Answer

I would highly recommend the video from Orbit MVI above it s going to help you understand the general pattern much better than my project s docs will at this moment

Casey Brooks · Answer

Also don t discount the usefulness of the Android Compose docs in CfD All the concepts are the same very little in there is truly Android specific So the official <https developer android com jetpack compose state|Managing State> doc is perfectly applicable in a Compose Desktop or Web application

Adam Powell · Answer

Most of the Android guidance that refers to androidx ViewModel is specifically about state that has a defined lifetime that outlives the composition for some reason There are plenty of reasons you might encounter this sort of thing outside of Android as well such as with navigation stacks so it is indeed conceptually applicable if not mechanically

Arkadii Ivanov · Answer

I agree with < Adam Powell> From my point of view there are two different concepts scoping the state to a screen + navigation and managing the state in the scope of the screen The former concept is usually handled by the various navigation libraries e g the official Android s `navigation compose` + `ViewModel` Decompose etc The later concept can be handled by the various MVx libraries

Casey Brooks · Answer

< rocketraman> To follow up on your interest in Ballast on Kotlin JS I ve now got some examples built with Compose Web running in the docs site