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78 lines
2 KiB
Text
78 lines
2 KiB
Text
= Active Model - defined interfaces for Rails
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Prior to Rails 3.0, if a plugin or gem developer wanted to be able to have
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an object interact with Action Pack helpers, it was required to either
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copy chunks of code from Rails, or monkey patch entire helpers to make them
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handle objects that did not look like Active Record. This generated code
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duplication and fragile applications that broke on upgrades.
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Active Model is a solution for this problem.
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Active Model provides a known set of interfaces that your objects can implement
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to then present a common interface to the Action Pack helpers.
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You can include functionality from the following modules:
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* Adding callbacks to your class
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class MyClass
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extend ActiveModel::Callbacks
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define_model_callbacks :create
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def create
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_run_create_callbacks do
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# Your create action methods here
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end
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end
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end
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...gives you before_create, around_create and after_create class methods that
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wrap your create method.
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{Learn more}[link:classes/ActiveModel/CallBacks.html]
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* For classes that already look like an Active Record object
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class MyClass
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include ActiveModel::Conversion
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end
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...returns the class itself when sent :to_model
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* Tracking changes in your object
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class Person
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include ActiveModel::Dirty
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define_attribute_methods [:name]
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def name
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@name
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end
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def name=(val)
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name_will_change!
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@name = val
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end
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def save
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@previously_changed = changes
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true
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end
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end
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...provides all the value tracking features implemented by ActiveRecord
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person = Person.new
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person.name # => nil
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person.changed? # => false
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person.name = 'bob'
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person.changed? # => true
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person.changed # => ['name']
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person.changes # => { 'name' => [nil, 'bob'] }
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person.name = 'robert'
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person.save
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person.previous_changes # => {'name' => ['bob, 'robert']}
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{Learn more}[link:classes/ActiveModel/Dirty.html]
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