Having problem with broadcasting to external topic

Phoenix Forum Questions / Help
1

I have EmployeeSocket in Endpoint.ex like this

  socket "/employee", MyAppWeb.EmployeeSocket,
    websocket: true,
    longpoll: false

And in emplyee_socket.ex

channel "store:*", MyAppWeb.StoreChannel

And also doing some authentication in connect function to let only employee join StoreChannel

If i get a new order from customer, I want to broadcast a message to StoreChannel to notify
employees about new order.
So I just tested code like this

In store_channel.ex

  @impl true
  def handle_in("new_order", payload, socket) do
    IO.puts("Incoming new order")
    {:noreply, socket}
  end

then tried in iex console

MyAppWeb.Endpoint.broadcast!("store:1", "new_order", %{message: "some message"})
:ok

I expected to see a message “Incoming new order”
But I don’t see any message.

What am I missing?

2

handle_in deals with messages coming into the system from connected clients. broadcast sends messages to connected clients. So to have your channel be aware of those you need to implement handle_out and disable fasttracking, which optimizes broadcasts to not involve the channel process. This can be done by using intercept for the message if you can live with the performance loss of doing that.

1 Like
3

Oh I missed this point.
So I tried to intercept outgoing event in channel using handle_out to see if it catches

intercept ["new_order"
 @impl true
  def handle_out("new_order", message, socket) do
    IO.puts("New order message sending out")
    {:noreply, socket}
  end

And it still doesn’t work.
There is no “New order message sending out” is printed in server log.

4

The problem is that I was running broadcast function in iex -S mix session. That is why I didn’t get a message.
I tried iex -S mix phx.server. it works!