Document Action Cable Connection Callbacks

Author: skryukov

actioncable/lib/action_cable/connection/callbacks.rb

@@ -4,6 +4,27 @@
 
 module ActionCable
   module Connection
+    # = Action Cable Connection Callbacks
+    #
+    # There are <tt>before_command</tt>, <tt>after_command</tt>, and <tt>around_command</tt> callbacks
+    # available to be invoked before, after or around every command received by a client respectively.
+    # The term "command" here refers to any interaction received by a client (subscribing, unsubscribing or performing actions):
+    #
+    #    module ApplicationCable
+    #      class Connection < ActionCable::Connection::Base
+    #        identified_by :user
+    #
+    #        around_command :set_current_account
+    #
+    #        private
+    #
+    #        def set_current_account
+    #          # Now all channels could use Current.account
+    #          Current.set(account: user.account) { yield }
+    #        end
+    #      end
+    #    end
+    #
     module Callbacks
       extend  ActiveSupport::Concern
       include ActiveSupport::Callbacks

guides/source/action_cable_overview.md

@@ -165,6 +165,29 @@ end
 
 [`rescue_from`]: https://api.rubyonrails.org/classes/ActiveSupport/Rescuable/ClassMethods.html#method-i-rescue_from
 
+#### Connection Callbacks
+
+There are `before_command`, `after_command`, and `around_command` callbacks available to be invoked before, after or around every command received by a client respectively.
+The term "command" here refers to any interaction received by a client (subscribing, unsubscribing or performing actions):
+
+```ruby
+# app/channels/application_cable/connection.rb
+module ApplicationCable
+  class Connection < ActionCable::Connection::Base
+    identified_by :user
+
+    around_command :set_current_account
+
+    private
+
+    def set_current_account
+      # Now all channels could use Current.account
+      Current.set(account: user.account) { yield }
+    end
+  end
+end
+```
+
 ### Channels
 
 A *channel* encapsulates a logical unit of work, similar to what a controller does in a