Module: ActiveModel::AttributeMethods
Relationships & Source Files | |
Namespace Children | |
Modules:
| |
Extension / Inclusion / Inheritance Descendants | |
Included In:
| |
Super Chains via Extension / Inclusion / Inheritance | |
Class Chain:
self,
::ActiveSupport::Concern
|
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Defined in: | activemodel/lib/active_model/attribute_methods.rb |
Overview
Provides a way to add prefixes and suffixes to your methods as well as handling the creation of ::ActiveRecord::Base
- like class methods such as table_name
.
The requirements to implement AttributeMethods
are to:
-
include ActiveModel::AttributeMethods
in your class. -
Call each of its methods you want to add, such as
attribute_method_suffix
orattribute_method_prefix
. -
Call
define_attribute_methods
after the other methods are called. -
Define the various generic
_attribute
methods that you have declared. -
Define an
attributes
method 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.
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
def attributes
{ 'name' => @name }
end
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
Constant Summary
-
CALL_COMPILABLE_REGEXP =
# File 'activemodel/lib/active_model/attribute_methods.rb', line 68/\A[a-zA-Z_]\w*[!?]?\z/
-
FORWARD_PARAMETERS =
# File 'activemodel/lib/active_model/attribute_methods.rb', line 69"*args"
-
NAME_COMPILABLE_REGEXP =
# File 'activemodel/lib/active_model/attribute_methods.rb', line 67/\A[a-zA-Z_]\w*[!?=]?\z/
Class Method Summary
::ActiveSupport::Concern
- Extended
class_methods | Define class methods from given block. |
included | Evaluate given block in context of base class, so that you can write class macros here. |
prepended | Evaluate given block in context of base class, so that you can write class macros here. |
Instance Method Summary
-
#attribute_missing(match, *args, &block)
#attribute_missing is like #method_missing, but for attributes.
-
#method_missing(method, *args, &block)
Allows access to the object attributes, which are held in the hash returned by
attributes
, as though they were first-class methods. - #respond_to?(method, include_private_methods = false) ⇒ Boolean
-
#respond_to_without_attributes?
A
Person
instance with aname
attribute can askperson.respond_to?(:name)
,person.respond_to?(:name=)
, andperson.respond_to?(:name?)
which will all returntrue
.
Dynamic Method Handling
This class handles dynamic methods through the method_missing method
#method_missing(method, *args, &block)
Allows access to the object attributes, which are held in the hash returned by attributes
, as though they were first-class methods. So a Person
class with a name
attribute can for example use Person#name
and Person#name=
and never directly use the attributes hash – except for multiple assignments with ActiveRecord::Base#attributes=
.
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
.
# File 'activemodel/lib/active_model/attribute_methods.rb', line 506
def method_missing(method, *args, &block) if respond_to_without_attributes?(method, true) super else match = matched_attribute_method(method.to_s) match ? attribute_missing(match, *args, &block) : super end end
DSL Calls
included
[ GitHub ]71 72 73 74
# File 'activemodel/lib/active_model/attribute_methods.rb', line 71
included do class_attribute :attribute_aliases, instance_writer: false, default: {} class_attribute :attribute_method_patterns, instance_writer: false, default: [ ClassMethods::AttributeMethodPattern.new ] end
Instance Method Details
#attribute_missing(match, *args, &block)
attribute_missing
is like #method_missing, but for attributes. When #method_missing is called we check to see if there is a matching attribute method. If so, we tell attribute_missing
to dispatch the attribute. This method can be overloaded to customize the behavior.
# File 'activemodel/lib/active_model/attribute_methods.rb', line 520
def attribute_missing(match, *args, &block) __send__(match.proxy_target, match.attr_name, *args, &block) end
#respond_to?(method, include_private_methods = false) ⇒ Boolean
# File 'activemodel/lib/active_model/attribute_methods.rb', line 529
def respond_to?(method, include_private_methods = false) if super 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. false else !matched_attribute_method(method.to_s).nil? end end
#respond_to_without_attributes?
A Person
instance with a name
attribute can ask person.respond_to?(:name)
, person.respond_to?(:name=)
, and person.respond_to?(:name?)
which will all return true
.
# File 'activemodel/lib/active_model/attribute_methods.rb', line 528
alias :respond_to_without_attributes? :respond_to?