Overview

StarView is an Elixir SDK for Datastar Server-Sent Events. It works with Plug and Phoenix, and uses Erlang's built-in :json module.

The Problem

Building Datastar apps in Elixir can mean a lot of repeated wiring. You start SSE responses, track which values need to reach the browser, render updated HTML, and keep event handlers mapped to the modules that own them.

StarView keeps that flow close to normal Phoenix controller code.

What StarView Adds

signal/3 sets a connection assign and exposes the same value as a Datastar signal. Function components can read the assign, while the browser receives the signal during the initial render or immediately during an SSE event.

def handle_event("increment", signals, conn) do
  conn
  |> assign(:computed_value, expensive_calculation(signals))
  |> signal(:count, signals["count"] + 1)
  |> patch_element(&history_item/1, to: "history-list", mode: :append)
end

Dispatch Flow

The Phoenix dispatcher starts the SSE response before your handler runs. Your controller handles the event and returns the updated connection:

@impl StarView
def handle_event("increment", signals, conn) do
  signal(conn, :count, Map.get(signals, "count", 0) + 1)
end

Any controller that uses use StarView is automatically dispatchable through StarView.Dispatch, so you do not maintain an allow-list for Phoenix controllers.

Next Steps

Start with the installation guide, then add the Phoenix web module section and routes. Once the app is running, the core guides cover patch_signals/3, patch_element/3, and optional per-tab stream deduplication.

Next Page → Installation