module ActionCable module Server # Broadcasting is how other parts of your application can send messages to a channel's subscribers. As explained in Channel, most of the time, these # broadcastings are streamed directly to the clients subscribed to the named broadcasting. Let's explain with a full-stack example: # # class WebNotificationsChannel < ApplicationCable::Channel # def subscribed # stream_from "web_notifications_#{current_user.id}" # end # end # # # Somewhere in your app this is called, perhaps from a NewCommentJob: # ActionCable.server.broadcast \ # "web_notifications_1", { title: "New things!", body: "All that's fit for print" } # # # Client-side CoffeeScript, which assumes you've already requested the right to send web notifications: # App.cable.subscriptions.create "WebNotificationsChannel", # received: (data) -> # new Notification data['title'], body: data['body'] module Broadcasting # Broadcast a hash directly to a named broadcasting. This will later be JSON encoded. def broadcast(broadcasting, message, coder: ActiveSupport::JSON) broadcaster_for(broadcasting, coder: coder).broadcast(message) end # Returns a broadcaster for a named broadcasting that can be reused. Useful when you have an object that # may need multiple spots to transmit to a specific broadcasting over and over. def broadcaster_for(broadcasting, coder: ActiveSupport::JSON) Broadcaster.new(self, String(broadcasting), coder: coder) end private class Broadcaster attr_reader :server, :broadcasting, :coder def initialize(server, broadcasting, coder:) @server, @broadcasting, @coder = server, broadcasting, coder end def broadcast(message) server.logger.info "[ActionCable] Broadcasting to #{broadcasting}: #{message.inspect}" payload = { broadcasting: broadcasting, message: message, coder: coder } ActiveSupport::Notifications.instrument("broadcast.action_cable", payload) do encoded = coder ? coder.encode(message) : message server.pubsub.broadcast broadcasting, encoded end end end end end end