Store for Plug.Sessions with PubSub features for Phoenix.LiveView

Setup

Use this in your Endpoint module when defining options for Plug.Sessions like so:

# lib/my_app_web/endpoint.ex
@session_options [
    store: PhoenixLiveSession,
    pub_sub: MyApp.PubSub,
    signing_salt: "your-salt",
]

Usage in Phoenix Controllers

You don’t need to do anything special to use PhoenixLiveSession in regular Phoenix controllers. Your sessions will continue to work the same as with other stores.

Usage in LiveViews

Use maybe_subscribe/2 in your mount/3 function to subscribe to LiveSession updates. Only sockets with connected? == true are subscribed by maybe_subscribe/2.

Once you’ve subscribed to a LiveSession, you can handle session updates with handle_info/2 and push session updates with put_session/3.

Example

def mount(_params, session, socket) do
  socket = socket
  |> PhoenixLiveSession.maybe_subscribe(session)
  |> put_session_assigns(session)

  {:ok, socket}
end

def handle_info({:live_session_updated, session}, socket) do
  {:noreply, put_session_assigns(socket, session)}
end

def handle_event("add_to_cart", %{"product_id" => product_id}, socket) do
  updated_cart = [product_id | socket.assigns.cart]
  PhoenixLiveSession.put_session(socket, "cart", updated_cart)

  {:noreply, socket}
end

defp put_sesion_assigns(socket, session) do
  socket
  |> assign(:shopping_cart, Map.get(session, "shopping_cart", []))
end

Options

• :pub_sub - Required.- Module for handling PubSub (e.g. MyApp.PubSub).
• :table - ETS table name. Defaults to :phoenix_live_sessions
• :lifetime - Lifetime (in ms) of sessions before they are cleared. Reads and writes refresh session lifetime. Defaults to two days.
• clean_interval - Interval (in ms) after which expired PhoenixLiveSession are cleared. Defaulst to 60 seconds.

Caveats

Since sessions are stored in memory, they will be lost when restarting your server and are not shared between servers in multi-node setups.