Module: ActiveModel::AttributeMethods
- Extended by:
- ActiveSupport::Concern
- Defined in:
- activemodel/lib/active_model/attribute_methods.rb
Overview
Active Model Attribute Methods
ActiveModel::AttributeMethods provides a way to add prefixes and suffixes to your methods as well as handling the creation of Active Record like class methods such as table_name.
The requirements to implement ActiveModel::AttributeMethods are to:
-
include ActiveModel::AttributeMethods in your object
-
Call each Attribute Method module method you want to add, such as attribute_method_suffix or attribute_method_prefix
-
Call define_attribute_methods after the other methods are called.
-
Define the various generic _attribute methods that you have declared
A minimal implementation could be:
class Person
include ActiveModel::AttributeMethods
attribute_method_affix :prefix => 'reset_', :suffix => '_to_default!'
attribute_method_suffix '_contrived?'
attribute_method_prefix 'clear_'
define_attribute_methods ['name']
attr_accessor :name
private
def attribute_contrived?(attr)
true
end
def clear_attribute(attr)
send("#{attr}=", nil)
end
def reset_attribute_to_default!(attr)
send("#{attr}=", "Default Name")
end
end
Notice that whenever you include ActiveModel::AttributeMethods in your class, it requires you to implement a attributes methods which returns a hash with each attribute name in your model as hash key and the attribute value as hash value.
Hash keys must be strings.
Defined Under Namespace
Modules: ClassMethods
Instance Method Summary (collapse)
-
- (Object) method_missing(method_id, *args, &block)
Allows access to the object attributes, which are held in the @attributes hash, as though they were first-class methods.
- - (Boolean) respond_to?(method, include_private_methods = false) (also: #respond_to_without_attributes?)
Methods included from ActiveSupport::Concern
append_features, extended, included
Dynamic Method Handling
This class handles dynamic methods through the method_missing method
- (Object) method_missing(method_id, *args, &block)
Allows access to the object attributes, which are held in the @attributes hash, as though they were first-class methods. So a Person class with a name attribute can use Person#name and Person#name= and never directly use the attributes hash -- except for multiple assigns with ActiveRecord#attributes=. A Milestone class can also ask Milestone#completed? to test that the completed attribute is not nil or 0.
It's also possible to instantiate related objects, so a Client class belonging to the clients table with a master_id foreign key can instantiate master through Client#master.
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# File 'activemodel/lib/active_model/attribute_methods.rb', line 358 def method_missing(method_id, *args, &block) method_name = method_id.to_s if match = match_attribute_method?(method_name) guard_private_attribute_method!(method_name, args) return __send__(match.target, match.attr_name, *args, &block) end super end |
Instance Method Details
- (Boolean) respond_to?(method, include_private_methods = false) Also known as: respond_to_without_attributes?
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# File 'activemodel/lib/active_model/attribute_methods.rb', line 371 def respond_to?(method, include_private_methods = false) if super return true elsif !include_private_methods && super(method, true) # If we're here then we haven't found among non-private methods # but found among all methods. Which means that the given method is private. return false elsif match_attribute_method?(method.to_s) return true end super end |