Listen to PubSub Events

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As mentioned in the installation guide you are able to configure PubSub events for each LiveResources individually. Backpex will use the configuration to publish deleted, updated and created events. Backpex will listen to these events and update the UI accordingly. Sometimes you may want to listen to these events and perform some custom actions. For example you want to show a toast to all users currently on the resource that a post has been created.

Customize Configuration

You may overwrite the PubSub configuration for your Posts LiveResource like this:

use Backpex.LiveResource,
  ...,
  pubsub: [
    server: Demo.PubSub
    topic: "posts"
  ]

If you do not set a topic yourself, we take the stringified version of the live resource name as the default topic.

iex(1)> to_string(DemoWeb.UserLive)
"Elixir.DemoWeb.UserLive"

The server can be configured in your config.exs:

config :backpex, pubsub_server: Demo.PubSub,

Listen to events

You can listen for Backpex PubSub events by implementing the Phoenix.LiveView handle_info/2 callback in your LiveResource module. You can attach this callback via an on_mount hook by setting the on_mount option in your LiveResource.

# in your resource configuration file
use Backpex.LiveResource,
  on_mount: __MODULE__,
  ...

  def on_mount(:default, _params, _session, socket) do
    socket = Phoenix.LiveView.attach_hook(socket, :handle_pubsub_messages, :handle_info, &handle_info/2)
    {:cont, socket}
  end

  def handle_info({"created", item}, socket) do
    # make something in response to the event
    {:halt, socket}
  end

  def handle_info({"updated", item}, socket) do
    # make something in response to the event
    {:halt, socket}
  end

  def handle_info({"deleted", item}, socket) do
    # make something in response to the event
    {:halt, socket}
  end

  ...
end