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-rw-r--r--activesupport/lib/active_support/log_subscriber.rb37
-rw-r--r--activesupport/lib/active_support/notifications.rb7
2 files changed, 35 insertions, 9 deletions
diff --git a/activesupport/lib/active_support/log_subscriber.rb b/activesupport/lib/active_support/log_subscriber.rb
index 0f7be06c8e..3c8fce222d 100644
--- a/activesupport/lib/active_support/log_subscriber.rb
+++ b/activesupport/lib/active_support/log_subscriber.rb
@@ -5,8 +5,8 @@ require "active_support/core_ext/class/attribute"
require "active_support/subscriber"
module ActiveSupport
- # ActiveSupport::LogSubscriber is an object set to consume
- # ActiveSupport::Notifications with the sole purpose of logging them.
+ # <tt>ActiveSupport::LogSubscriber</tt> is an object set to consume
+ # <tt>ActiveSupport::Notifications</tt> with the sole purpose of logging them.
# The log subscriber dispatches notifications to a registered object based
# on its given namespace.
#
@@ -29,13 +29,36 @@ module ActiveSupport
# subscriber, the line above should be called after your
# <tt>ActiveRecord::LogSubscriber</tt> definition.
#
- # After configured, whenever a "sql.active_record" notification is published,
- # it will properly dispatch the event (ActiveSupport::Notifications::Event) to
- # the sql method.
+ # After configured, whenever a <tt>"sql.active_record"</tt> notification is published,
+ # it will properly dispatch the event
+ # (<tt>ActiveSupport::Notifications::Event</tt>) to the sql method.
+ #
+ # Being an <tt>ActiveSupport::Notifications</tt> consumer,
+ # <tt>ActiveSupport::LogSubscriber</tt> exposes a simple interface to check if
+ # instrumented code raises an exception. It is common to log a different
+ # message in case of an error, and this can be achieved by extending
+ # the previous example:
+ #
+ # module ActiveRecord
+ # class LogSubscriber < ActiveSupport::LogSubscriber
+ # def sql(event)
+ # exception = event.payload[:exception]
+ #
+ # if exception
+ # exception_object = event.payload[:exception_object]
+ #
+ # "[ERROR] #{event.payload[:name]}: #{exception.join(', ')} " \
+ # "(#{exception_object.backtrace.first})"
+ # else
+ # # standard logger code
+ # end
+ # end
+ # end
+ # end
#
# Log subscriber also has some helpers to deal with logging and automatically
- # flushes all logs when the request finishes (via action_dispatch.callback
- # notification) in a Rails environment.
+ # flushes all logs when the request finishes
+ # (via <tt>action_dispatch.callback</tt> notification) in a Rails environment.
class LogSubscriber < Subscriber
# Embed in a String to clear all previous ANSI sequences.
CLEAR = "\e[0m"
diff --git a/activesupport/lib/active_support/notifications.rb b/activesupport/lib/active_support/notifications.rb
index 01cc363e2b..d968b3a216 100644
--- a/activesupport/lib/active_support/notifications.rb
+++ b/activesupport/lib/active_support/notifications.rb
@@ -67,9 +67,12 @@ module ActiveSupport
# have a key <tt>:exception</tt> with an array of two elements as value: a string with
# the name of the exception class, and the exception message.
# The <tt>:exception_object</tt> key of the payload will have the exception
- # itself as the value.
+ # itself as the value:
#
- # As the previous example depicts, the class <tt>ActiveSupport::Notifications::Event</tt>
+ # event.payload[:exception] # => ["ArgumentError", "Invalid value"]
+ # event.payload[:exception_object] # => #<ArgumentError: Invalid value>
+ #
+ # As the earlier example depicts, the class <tt>ActiveSupport::Notifications::Event</tt>
# is able to take the arguments as they come and provide an object-oriented
# interface to that data.
#