Action Cable Server Broadcasting
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']
Namespace
Class
Methods
Instance Public methods
broadcast(broadcasting, message, coder: ActiveSupport::JSON)
Broadcast a hash directly to a named broadcasting. This will later be JSON encoded.
📝 Source code
# File actioncable/lib/action_cable/server/broadcasting.rb, line 26
def broadcast(broadcasting, message, coder: ActiveSupport::JSON)
broadcaster_for(broadcasting, coder: coder).broadcast(message)
endbroadcaster_for(broadcasting, coder: ActiveSupport::JSON)
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.
📝 Source code
# File actioncable/lib/action_cable/server/broadcasting.rb, line 32
def broadcaster_for(broadcasting, coder: ActiveSupport::JSON)
Broadcaster.new(self, String(broadcasting), coder: coder)
end