mirror of
https://github.com/rails/rails.git
synced 2022-11-09 12:12:34 -05:00
80 lines
2.3 KiB
Text
80 lines
2.3 KiB
Text
= Active Model - defined interfaces for Rails
|
|
|
|
Prior to Rails 3.0, if a plugin or gem developer wanted to be able to have
|
|
an object interact with Action Pack helpers, it was required to either
|
|
copy chunks of code from Rails, or monkey patch entire helpers to make them
|
|
handle objects that did not look like Active Record. This generated code
|
|
duplication and fragile applications that broke on upgrades.
|
|
|
|
Active Model is a solution for this problem.
|
|
|
|
Active Model provides a known set of interfaces that your objects can implement
|
|
to then present a common interface to the Action Pack helpers. You can include
|
|
functionality from the following modules:
|
|
|
|
* Adding attribute magic to your objects
|
|
|
|
Add prefixes and suffixes to defined attribute methods...
|
|
|
|
class Person
|
|
include ActiveModel::AttributeMethods
|
|
|
|
attribute_method_prefix 'clear_'
|
|
define_attribute_methods [:name, :age]
|
|
|
|
attr_accessor :name, :age
|
|
|
|
def clear_attribute(attr)
|
|
send("#{attr}=", nil)
|
|
end
|
|
end
|
|
|
|
...gives you clear_name, clear_age.
|
|
|
|
{Learn more}[link:classes/ActiveModel/AttributeMethods.html]
|
|
|
|
* Adding callbacks to your objects
|
|
|
|
class Person
|
|
extend ActiveModel::Callbacks
|
|
define_model_callbacks :create
|
|
|
|
def create
|
|
_run_create_callbacks do
|
|
# Your create action methods here
|
|
end
|
|
end
|
|
end
|
|
|
|
...gives you before_create, around_create and after_create class methods that
|
|
wrap your create method.
|
|
|
|
{Learn more}[link:classes/ActiveModel/CallBacks.html]
|
|
|
|
* For classes that already look like an Active Record object
|
|
|
|
class Person
|
|
include ActiveModel::Conversion
|
|
end
|
|
|
|
...returns the class itself when sent :to_model
|
|
|
|
{Learn more}[link:classes/ActiveModel/Conversion.html]
|
|
|
|
* Tracking changes in your object
|
|
|
|
Provides all the value tracking features implemented by ActiveRecord...
|
|
|
|
person = Person.new
|
|
person.name # => nil
|
|
person.changed? # => false
|
|
person.name = 'bob'
|
|
person.changed? # => true
|
|
person.changed # => ['name']
|
|
person.changes # => { 'name' => [nil, 'bob'] }
|
|
person.name = 'robert'
|
|
person.save
|
|
person.previous_changes # => {'name' => ['bob, 'robert']}
|
|
|
|
{Learn more}[link:classes/ActiveModel/Dirty.html]
|
|
|