Merge pull request #34 from lsylvester/add-broadcast_to-and-stream_for-methods-to-channel

add broadcast_to and stream_for methods as per #26

7 files changed, 85 insertions, 11 deletions

diff --git a/lib/action_cable/channel.rb b/lib/action_cable/channel.rb
index 9e4d3d3f93..3b973ba0a7 100644
--- a/lib/action_cable/channel.rb
+++ b/lib/action_cable/channel.rb
@@ -1,7 +1,9 @@
 module ActionCable
   module Channel
     autoload :Base, 'action_cable/channel/base'
+    autoload :Broadcasting, 'action_cable/channel/broadcasting'
     autoload :Callbacks, 'action_cable/channel/callbacks'
+    autoload :Naming, 'action_cable/channel/naming'
     autoload :PeriodicTimers, 'action_cable/channel/periodic_timers'
     autoload :Streams, 'action_cable/channel/streams'
   end
diff --git a/lib/action_cable/channel/base.rb b/lib/action_cable/channel/base.rb
index d6bd98d180..2f1b4a187d 100644
--- a/lib/action_cable/channel/base.rb
+++ b/lib/action_cable/channel/base.rb
@@ -68,6 +68,8 @@ module ActionCable
       include Callbacks
       include PeriodicTimers
       include Streams
+      include Naming
+      include Broadcasting
 
       on_subscribe   :subscribed
       on_unsubscribe :unsubscribed
diff --git a/lib/action_cable/channel/broadcasting.rb b/lib/action_cable/channel/broadcasting.rb
new file mode 100644
index 0000000000..ee4117bc0a
--- /dev/null
+++ b/lib/action_cable/channel/broadcasting.rb
@@ -0,0 +1,27 @@
+module ActionCable
+  module Channel
+    module Broadcasting
+      extend ActiveSupport::Concern
+
+      delegate :broadcasting_for, to: :class
+
+      class_methods do
+        # Broadcast a hash to a unique broadcasting for this <tt>model</tt> in this channel.
+        def broadcast_to(model, message)
+          ActionCable.server.broadcast(broadcasting_for([ channel_name, model ]), message)
+        end
+
+        def broadcasting_for(model) #:nodoc:
+          case
+          when model.is_a?(Array)
+            model.map { |m| broadcasting_for(m) }.join(':')
+          when model.respond_to?(:to_gid_param)
+            model.to_gid_param
+          else
+            model.to_param
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/action_cable/channel/naming.rb b/lib/action_cable/channel/naming.rb
new file mode 100644
index 0000000000..4c9d53b15a
--- /dev/null
+++ b/lib/action_cable/channel/naming.rb
@@ -0,0 +1,22 @@
+module ActionCable
+  module Channel
+    module Naming
+      extend ActiveSupport::Concern
+
+      class_methods do
+        # Returns the name of the channel, underscored, without the <tt>Channel</tt> ending.
+        # If the channel is in a namespace, then the namespaces are represented by single
+        # colon separators in the channel name.
+        #
+        #   ChatChannel.channel_name # => 'chat'
+        #   Chats::AppearancesChannel.channel_name # => 'chats:appearances'
+        def channel_name
+          @channel_name ||= name.sub(/Channel$/, '').gsub('::',':').underscore
+        end
+      end
+
+      # Delegates to the class' <tt>channel_name</tt>
+      delegate :channel_name, to: :class
+    end
+  end
+end
diff --git a/lib/action_cable/channel/streams.rb b/lib/action_cable/channel/streams.rb
index 6a3dc76c1d..f711b065ca 100644
--- a/lib/action_cable/channel/streams.rb
+++ b/lib/action_cable/channel/streams.rb
@@ -1,7 +1,7 @@
 module ActionCable
   module Channel
     # Streams allow channels to route broadcastings to the subscriber. A broadcasting is an discussed elsewhere a pub/sub queue where any data
-    # put into it is automatically sent to the clients that are connected at that time. It's purely an online queue, though. If you're not 
+    # put into it is automatically sent to the clients that are connected at that time. It's purely an online queue, though. If you're not
     # streaming a broadcasting at the very moment it sends out an update, you'll not get that update when connecting later.
     #
     # Most commonly, the streamed broadcast is sent straight to the subscriber on the client-side. The channel just acts as a connector between
@@ -12,7 +12,7 @@ module ActionCable
     #     def follow(data)
     #       stream_from "comments_for_#{data['recording_id']}"
     #     end
-    #   
+    #
     #     def unfollow
     #       stop_all_streams
     #     end
@@ -23,23 +23,37 @@ module ActionCable
     #
     #   ActionCable.server.broadcast "comments_for_45", author: 'DHH', content: 'Rails is just swell'
     #
-    # If you don't just want to parlay the broadcast unfiltered to the subscriber, you can supply a callback that let's you alter what goes out. 
+    # If you have a stream that is related to a model, then the broadcasting used can be generated from the model and channel.
+    # The following example would to subscribe to a broadcasting that would be something like `comments:Z2lkOi8vVGVzdEFwcC9Qb3N0LzE`
+    #
+    #   class CommentsChannel < ApplicationCable::Channel
+    #     def subscribed
+    #       post = Post.find(params[:id])
+    #       stream_for post
+    #     end
+    #   end
+    #
+    # You can then broadcast to this channel using:
+    #
+    #   CommentsChannel.broadcast_to(@post)
+    #
+    # If you don't just want to parlay the broadcast unfiltered to the subscriber, you can supply a callback that let's you alter what goes out.
     # Example below shows how you can use this to provide performance introspection in the process:
     #
     #   class ChatChannel < ApplicationCable::Channel
     #    def subscribed
     #      @room = Chat::Room[params[:room_number]]
-    #  
-    #      stream_from @room.channel, -> (message) do
+    #
+    #      stream_for @room, -> (message) do
     #        message = ActiveSupport::JSON.decode(m)
-    #  
+    #
     #        if message['originated_at'].present?
     #          elapsed_time = (Time.now.to_f - message['originated_at']).round(2)
-    #  
+    #
     #          ActiveSupport::Notifications.instrument :performance, measurement: 'Chat.message_delay', value: elapsed_time, action: :timing
     #          logger.info "Message took #{elapsed_time}s to arrive"
     #        end
-    #  
+    #
     #        transmit message
     #      end
     #    end
@@ -63,6 +77,13 @@ module ActionCable
         logger.info "#{self.class.name} is streaming from #{broadcasting}"
       end
 
+      # Start streaming the pubsub queue for the <tt>model</tt> in this channel. Optionally, you can pass a
+      # <tt>callback</tt> that'll be used instead of the default of just transmitting the updates straight
+      # to the subscriber.
+      def stream_for(model, callback = nil)
+        stream_from(broadcasting_for([ channel_name, model ]), callback)
+      end
+
       def stop_all_streams
         streams.each do |broadcasting, callback|
           pubsub.unsubscribe_proc broadcasting, callback
diff --git a/lib/action_cable/server/base.rb b/lib/action_cable/server/base.rb
index fe7966e090..b09fbf6da4 100644
--- a/lib/action_cable/server/base.rb
+++ b/lib/action_cable/server/base.rb
@@ -9,7 +9,7 @@ module ActionCable
       include ActionCable::Server::Connections
 
       cattr_accessor(:config, instance_accessor: true) { ActionCable::Server::Configuration.new }
-      
+
       def self.logger; config.logger; end
       delegate :logger, to: :config
 
@@ -56,7 +56,7 @@ module ActionCable
             logger.info "[ActionCable] Redis reconnect failed."
             # logger.info "[ActionCable] Redis reconnected. Closing all the open connections."
             # @connections.map &:close
-          end            
+          end
         end
       end
 
diff --git a/lib/action_cable/server/broadcasting.rb b/lib/action_cable/server/broadcasting.rb
index 4f72ffd96f..037b98951e 100644
--- a/lib/action_cable/server/broadcasting.rb
+++ b/lib/action_cable/server/broadcasting.rb
@@ -32,7 +32,7 @@ module ActionCable
       # The redis instance used for broadcasting. Not intended for direct user use.
       def broadcasting_redis
         @broadcasting_redis ||= Redis.new(config.redis)
-      end      
+      end
 
       private
         class Broadcaster