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LiveView

[Source]

Server-side view that manages state and renders HTML.

Implement this trait to define a LiveView:

  • mount initializes assigns on the socket when the connection is established.
  • handle_event responds to client interactions (clicks, form submits) by updating assigns on the socket.
  • render produces HTML from the current assigns. This is a pure function of data — the box receiver prevents mutation during rendering.
trait ref LiveView

Public Functions

mount

[Source]

Called when a connection is established or when the view is rendered for HTTP response via PageRenderer. Use socket.assign() to set initial state.

Check socket.connected() to distinguish WebSocket mount (true) from HTTP render (false) — for example, to skip subscribing to PubSub topics during HTTP render.

fun ref mount(
  socket: Socket ref)
: None val

Parameters

Returns

handle_event

[Source]

Called when the client sends a UI event (e.g., a button click or form change/submission). Use socket.assign() to update state — the framework re-renders automatically if any assigns changed.

fun ref handle_event(
  event: String val,
  payload: (JsonObject val | JsonArray val | String val | 
    I64 val | F64 val | Bool val | 
    None val),
  socket: Socket ref)
: None val

Parameters

Returns

handle_info

[Source]

Called when an external actor sends a message to this connection via PubSub or direct InfoReceiver.info calls.

Default implementation does nothing. Override to handle server-push messages from timers, background jobs, or PubSub topics.

fun ref handle_info(
  message: Any val,
  socket: Socket ref)
: None val

Parameters

Returns

render

[Source]

Return the full HTML for the current state. Partial because rendering may fail (e.g., missing template variable). On failure the framework keeps the last successfully rendered HTML and sends an error to the client.

The returned HTML must have a single root element (e.g., wrapped in a <div>) for morphdom to work correctly during DOM patching.

fun box render(
  assigns: Assigns box)
: String val ?

Parameters

Returns

render_parts

[Source]

Drive the given sink with static/dynamic template output for efficient wire updates.

When this returns true, the framework sends static template parts once per connection and only changed dynamic slot values on subsequent renders. When it returns false (the default), the framework falls back to render() and sends full HTML every time.

Override this to enable split rendering. Typical implementation:

fun box render_parts(assigns: Assigns box,
  sink: templates.TemplateSink ref): Bool
=>
  try
    _template.render_to(sink, assigns.template_values())?
    true
  else
    false
  end

fun box render_parts(
  assigns: Assigns box,
  sink: TemplateSink ref)
: Bool val

Parameters

Returns