Hello, Im working on a MVI implementation and I want to know how I can structure my State. I though on a simple data class like (val isLoading, val content, val error, etc) and also for a sealed class like State { Loading, Error, Content, Idle }. I like the sealed class approach but i do not know how I can access to previous state. any idea or a better approach for sealed class for State

What do you mean with "previous state"?

data class

and

sealed class

are totally different.

data class

is product type and

sealed class

is sum type all that means is that you have different number of cases to handle

Im working with sealed class for MviState (State.Loading, State.Content, State.Error), but my guess if how to manage this scenario. 1. Action GetUsers -> State.Loading and then State.Content 2. Action.RefreshUsers -> ??? if I set State.Loading, I will loss the State.Content (prev state), so if there is any error I will loss the Content

sealed class

on the other hand has a lot less, potentially, cases to handle

Do you have any reducer or something like that?

if you have

sealed class

with

Loading

,

Error

and

Success

than you have only 3 states to handle.

Success

probably has some data so you need to handle those too but it reduces the number of cases because it only has 1 for

Error

and 1 for 1

Loading

So for example, you loaded data and then you refresh and get an error, how do you manage that to get the prev state, bc you are in Error State there

depends. usually I go one of two directions: 1. I do event sourcing -> keep record of all states 2. I save success state in local variable approach varies based on requirements

@Emiliano Schiavone why do you want to get to the previous state when you have an error state?

@Orhan Tozan bc in some case you display an error state but you have data, for example if you are refreshing data and you get an error, you had data before refreshing

Ok, in that case, your error state needs to have that data. But in your case, I would just give the Data state an error property

and you can have parts of the UI react to specific state