_blatantly copied from this email by JeremyKemper on the mailing list _
Timestamping callbacks are set up by default for columns named created_at/created_on and updated_at/updated_on. See http://rails.rubyonrails.com/classes/ActiveRecord/Timestamp.html
Using callbacks
Callbacks let you set up “triggers” like this easily. You can reimplement timestamping yourself:
class Foo < ActiveRecord::Base
before_create { |foo| foo.created_at = Time.now }
before_save { |foo| foo.updated_at = Time.now }
end
Package it in a module
Wonderful! Now say we want timestamps in our other models. Let’s make a module to mix in the behavior:
module Timestamped
# Invoked when "include Timestamped" is called in base_class.
def self.append_features(base_class)
base_class.before_create { |model| model.created_at = Time.now }
base_class.before_save { |model| model.updated_at = Time.now }
end
end
It can now be mixed in to a model.
class Foo < ActiveRecord::Base
include Timestamped
end
Make it generic
Then say this is so useful we’d like to add it to any models with these columns:
/lib/timestamped.rb
module Timestamped
def self.append_features(base)
base.before_create do |model|
model.created_at ||= Time.now if model.respond_to?(:created_at)
end
base.before_save do |model|
model.updated_at = Time.now if model.respond_to?(:updated_at)
end
end
end
Extend ActiveRecord, which extends all of your models with this module.
in /config/environment.rb
require 'timestamped'
class ActiveRecord::Base
include Timestamped
end
See UnderstandingWhatMethodsGoWhere for further discussion about where these methods/modules could be placed.
category: Example
_blatantly copied from this email by JeremyKemper on the mailing list _
Timestamping callbacks are set up by default for columns named created_at/created_on and updated_at/updated_on. See http://rails.rubyonrails.com/classes/ActiveRecord/Timestamp.html
Using callbacks
Callbacks let you set up “triggers” like this easily. You can reimplement timestamping yourself:
class Foo < ActiveRecord::Base
before_create { |foo| foo.created_at = Time.now }
before_save { |foo| foo.updated_at = Time.now }
end
Package it in a module
Wonderful! Now say we want timestamps in our other models. Let’s make a module to mix in the behavior:
module Timestamped
# Invoked when "include Timestamped" is called in base_class.
def self.append_features(base_class)
base_class.before_create { |model| model.created_at = Time.now }
base_class.before_save { |model| model.updated_at = Time.now }
end
end
It can now be mixed in to a model.
class Foo < ActiveRecord::Base
include Timestamped
end
Make it generic
Then say this is so useful we’d like to add it to any models with these columns:
/lib/timestamped.rb
module Timestamped
def self.append_features(base)
base.before_create do |model|
model.created_at ||= Time.now if model.respond_to?(:created_at)
end
base.before_save do |model|
model.updated_at = Time.now if model.respond_to?(:updated_at)
end
end
end
Extend ActiveRecord, which extends all of your models with this module.
in /config/environment.rb
require 'timestamped'
class ActiveRecord::Base
include Timestamped
end
See UnderstandingWhatMethodsGoWhere for further discussion about where these methods/modules could be placed.
category: Example