event-observer-compose

event-observer-compose is the UI-facing module for Jetpack Compose Multiplatform. It provides a declarative rendering DSL to handle the states of a DataResult or ResponseFlow.

Install

dependencies {
    implementation("io.github.matheus-corregiari:event-observer-compose:<version>")
}

Core Concept

The entry point for Compose integration is the .composable extension property, which converts a Flow<DataResult<T>> (or a single DataResult<T>) into a ComposableDataResult<T>.

You then use Unwrap to define how each state should be rendered.

Usage

Basic Example

val flow: ResponseFlow<String> = ...

flow.composable.Unwrap {
    OnShowLoading { CircularProgressIndicator() }
    OnData { data -> Text("Content: $data") }
    OnError { error -> Text("Error: ${error.message}") }
}

Animations

By default, ComposableDataResult uses AnimatedVisibility (fade-in/fade-out) when switching between states. You can customize or disable this:

flow.composable
    .animation {
        enabled = true
        defaultEnterDuration = 300.milliseconds
        defaultExitDuration = 200.milliseconds
    }
    .Unwrap {
        OnData { data -> Text(data) }
    }

To disable animations globally:

ComposableDataResult.AnimationConfig.enabledByDefault = false

Side Effects (Non-Compose)

If you need to trigger non-UI side effects (like logging) when a state changes, use outsideComposable:

flow.composable
    .outsideComposable {
        error { throwable -> Logger.log(throwable) }
    }
    .Unwrap {
        OnData { data -> Text(data) }
    }

Available Observers (inside Unwrap)

Observer	Triggered when...
OnData	Data is present, regardless of status (Success, Error, Loading).
OnSuccess	DataResult is Success.
OnShowLoading	DataResult is Loading.
OnHideLoading	DataResult transitions out of Loading.
OnError	DataResult is Error.
OnEmpty	Data is a collection and it is empty.
OnNotEmpty	Data is a collection and it is NOT empty.
OnSingle	Data is a collection and has exactly one item.
OnMany	Data is a collection and has multiple items.
OnNone	DataResult is in the 'None' state.
OnResult	On every emission.
OnStatus	Matches a specific DataResultStatus.

State Collection

Unwrap uses collectAsStateWithLifecycle() when a LifecycleOwner is available (defaulting to LocalLifecycleOwner.current), ensuring efficient and lifecycle-aware collection.

For manual control, you can use collectAsComposableState():

val compState by flow.collectAsComposableState()
compState.Unwrap {
    OnData { data -> Text(data) }
}