Returning multiple results

An action can return a List<?> to apply more than one effect in a single response.

All effects in the list are processed by the frontend in the same request cycle. There is no extra round-trip.

Basic example

@Button
public List<?> save() {
    productRepository.save(id, name, status);
    return List.of(
        new Message("Product saved"),
        new State(this)
    );
}

What happens here:

Message("Product saved") → shows a success toast
State(this) → refreshes the form with the current ViewModel state

@Button
@Action(validationRequired = true)
public List<?> publish() {
    status = Status.Available;
    productRepository.save(id, name, status);
    return List.of(
        new Message("Product is now available"),
        URI.create("/products/" + id + "/detail")
    );
}

Message shows feedback before navigation starts
URI navigates to the product detail page

Combining message and UICommand

@Toolbar
public List<?> closeAndNotify() {
    auditService.log(id, "closed");
    return List.of(
        new Message("Session closed"),
        UICommand.navigateTo("/dashboard")
    );
}

Combining State and UICommand

Use this when you want to update visible state and also trigger a browser-level command:

@Button
public List<?> refresh() {
    stockCount = inventoryService.getStock(id);
    return List.of(
        new State(this),
        UICommand.pushStateToHistory("/products/" + id + "?refreshed=true")
    );
}

Order of effects

Effects are applied in list order. In practice, the order matters only when one effect depends on another (for example, showing a message before navigating away).

When to use a List

Use a List<?> when a single action naturally produces more than one outcome — feedback plus navigation, state update plus history push, and so on. For a single outcome, return the effect directly.