state.md

State

To check the definition of a State in Nimbus and its purposes, please check the specification.

Local states

Nimbus compose takes care of the local states for you. You don't need to worry about it! The lib processes the json and calculates the state values before sending data to the UI layer that renders the components.

Event states

It's very simple to create Components with events that use implicit states. See the example below for a component that renders a text input.

@ServerDrivenComponent
@Composable
fun NimbusTextField(text: String, onChange: (String) -> Unit) {
    TextField(value = text, onValueChange = {
        onChange(it)
    })
}

Notice that the component doesn't become coupled to Nimbus. This is exactly what you would do for any Component in Compose.

Events always create states of their own named just like themselves. The onChange event above will expose a state called onChange for everything in its scope.

The string passed to the onChange function will update the current value of the event state, making it available for anything that might need it, like a setState action.

Global State

The Global state will probably be removed in the next builds. Consider Application Managed States instead.

Application Managed States

You can have application managed states that are shared with your server driven views.

Let's say you need a state to store all products in the shopping cart, this state must be the same throughout the entire application and it must be accessed from both native views and Server Driven Views.

1. Create the state:

val cartState = ServerDrivenState("cart", emptyList())

2. Provide it to the nimbus instance:

val nimbus = Nimbus(
    // ...
    states = listOf(cartState)
)

Now, the cart is accessible from within any Server Driven View of nimbus through the state id "cart". The current state value can be read by calling cartState.get().

Important (1): state values must be primitive types, maps of primitive types or lists of primitive types, i.e. deserializable. We do intend to make this better before releasing a stable version.

Important (2): states don't implement the observable pattern, but, if you need, you can still observe it by attaching your logic to the Nimbus Dependency Graph. We'll make this process far easier in the future, but for now, we recommend contacting a developer of this lib for further information.

Read next

👉 Operations