I am new to Elixir and Phoenix, so I apologize if the question is stupid.

I am developing an ecommerce site, and I have a cart drawer located in a layout, using LiveComponent.

After adding an item to cart from another component, that as I understand it, lives in another process, I want to send an update to this LiveComponent so that it updates without a page refresh or navigation.

I found send_update which seems to do what I want Phoenix.LiveView — Phoenix LiveView v1.0.0-rc.1

To use this, I need to find PID of this other Liveview. Things I tried:

• Process.info(self()) Does not return assigned name of the process
• Process.register(self(), :cart_liveview) Fails due to a name already existing
• Using the id that I pass to live_render from the layout, to render everything. Does not find it.

I am using Process.whereis to get PID from name.

Relevant code:

handle_event snippet on product page

      # Save
      properties_enc = Jason.encode!(values)
      Carts.add_to_cart(cart_id, product_id, properties_enc)
      # PID<0.4190.0>
      pid = Process.whereis(:cart_liveview)
      send_update(CartModal, id: "cart_modal", hello: "from_save")

      {:noreply,
       socket
       |> push_event("js-exec", %{
         to: "#confirm-modal",
         attr: "data-show-drawer"
       })}

Liveview load on layout

<div class="flex items-center gap-4 font-semibold leading-6 text-zinc-900">
      <%= live_render(@socket, PhoenixDemoWeb.Layouts.Components.CartLiveView, id: :cart_liveview) %>
    </div>

Live Component load

defmodule PhoenixDemoWeb.Layouts.Components.CartLiveView do
  use PhoenixDemoWeb, :live_view

  alias PhoenixDemoWeb.PutCartCookie
  alias PhoenixDemo.Carts

  @impl true
  def mount(_params, session, socket) do
    # Load cart
    cart_id = session[PutCartCookie.cart_id_cookie_name()]
    cart = Carts.get_cart_with_products(cart_id)
    socket = assign(socket, cart: cart)

    {:ok, socket}
  end

  @impl true
  def render(assigns) do
    ~H"""
    <.live_component
      module={PhoenixDemoWeb.Layouts.Components.CartModal}
      id="cart_modal"
      cart={@cart}
    />
    """
  end
end

Any ideas? Does what I’m doing even make sense?