module ActiveModel::AttributeMethods::ClassMethods
Public Instance Methods
Allows you to make aliases for attributes.
class Person include ActiveModel::AttributeMethods attr_accessor :name attribute_method_suffix '_short?' define_attribute_methods :name alias_attribute :nickname, :name private def attribute_short?(attr) send(attr).length < 5 end end person = Person.new person.name = 'Bob' person.name # => "Bob" person.nickname # => "Bob" person.name_short? # => true person.nickname_short? # => true
# File lib/active_model/attribute_methods.rb, line 208 def alias_attribute(new_name, old_name) self.attribute_aliases = attribute_aliases.merge(new_name.to_s => old_name.to_s) attribute_method_matchers.each do |matcher| matcher_new = matcher.method_name(new_name).to_s matcher_old = matcher.method_name(old_name).to_s define_proxy_call false, self, matcher_new, matcher_old end end
Returns the original name for the alias name
# File lib/active_model/attribute_methods.rb, line 223 def attribute_alias(name) attribute_aliases[name.to_s] end
Is new_name
an alias?
# File lib/active_model/attribute_methods.rb, line 218 def attribute_alias?(new_name) attribute_aliases.key? new_name.to_s end
Declares a method available for all attributes with the given prefix and
suffix. Uses method_missing
and respond_to?
to
rewrite the method.
#{prefix}#{attr}#{suffix}(*args, &block)
to
#{prefix}attribute#{suffix}(#{attr}, *args, &block)
An #{prefix}attribute#{suffix}
instance method must exist and
accept at least the attr
argument.
class Person include ActiveModel::AttributeMethods attr_accessor :name attribute_method_affix prefix: 'reset_', suffix: '_to_default!' define_attribute_methods :name private def reset_attribute_to_default!(attr) send("#{attr}=", 'Default Name') end end person = Person.new person.name # => 'Gem' person.reset_name_to_default! person.name # => 'Default Name'
# File lib/active_model/attribute_methods.rb, line 179 def attribute_method_affix(*affixes) self.attribute_method_matchers += affixes.map! { |affix| AttributeMethodMatcher.new prefix: affix[:prefix], suffix: affix[:suffix] } undefine_attribute_methods end
Declares a method available for all attributes with the given prefix. Uses
method_missing
and respond_to?
to rewrite the
method.
#{prefix}#{attr}(*args, &block)
to
#{prefix}attribute(#{attr}, *args, &block)
An instance method #{prefix}attribute
must exist and accept at
least the attr
argument.
class Person include ActiveModel::AttributeMethods attr_accessor :name attribute_method_prefix 'clear_' define_attribute_methods :name private def clear_attribute(attr) send("#{attr}=", nil) end end person = Person.new person.name = 'Bob' person.name # => "Bob" person.clear_name person.name # => nil
# File lib/active_model/attribute_methods.rb, line 108 def attribute_method_prefix(*prefixes) self.attribute_method_matchers += prefixes.map! { |prefix| AttributeMethodMatcher.new prefix: prefix } undefine_attribute_methods end
Declares a method available for all attributes with the given suffix. Uses
method_missing
and respond_to?
to rewrite the
method.
#{attr}#{suffix}(*args, &block)
to
attribute#{suffix}(#{attr}, *args, &block)
An attribute#{suffix}
instance method must exist and accept at
least the attr
argument.
class Person include ActiveModel::AttributeMethods attr_accessor :name attribute_method_suffix '_short?' define_attribute_methods :name private def attribute_short?(attr) send(attr).length < 5 end end person = Person.new person.name = 'Bob' person.name # => "Bob" person.name_short? # => true
# File lib/active_model/attribute_methods.rb, line 143 def attribute_method_suffix(*suffixes) self.attribute_method_matchers += suffixes.map! { |suffix| AttributeMethodMatcher.new suffix: suffix } undefine_attribute_methods end
Declares an attribute that should be prefixed and suffixed by
ActiveModel::AttributeMethods
.
To use, pass an attribute name (as string or symbol). Be sure to declare
define_attribute_method
after you define any prefix, suffix or
affix method, or they will not hook in.
class Person include ActiveModel::AttributeMethods attr_accessor :name attribute_method_suffix '_short?' # Call to define_attribute_method must appear after the # attribute_method_prefix, attribute_method_suffix or # attribute_method_affix declarations. define_attribute_method :name private def attribute_short?(attr) send(attr).length < 5 end end person = Person.new person.name = 'Bob' person.name # => "Bob" person.name_short? # => true
# File lib/active_model/attribute_methods.rb, line 284 def define_attribute_method(attr_name) attribute_method_matchers.each do |matcher| method_name = matcher.method_name(attr_name) unless instance_method_already_implemented?(method_name) generate_method = "define_method_#{matcher.method_missing_target}" if respond_to?(generate_method, true) send(generate_method, attr_name.to_s) else define_proxy_call true, generated_attribute_methods, method_name, matcher.method_missing_target, attr_name.to_s end end end attribute_method_matchers_cache.clear end
Declares the attributes that should be prefixed and suffixed by
ActiveModel::AttributeMethods
.
To use, pass attribute names (as strings or symbols). Be sure to declare
define_attribute_methods
after you define any prefix, suffix
or affix methods, or they will not hook in.
class Person include ActiveModel::AttributeMethods attr_accessor :name, :age, :address attribute_method_prefix 'clear_' # Call to define_attribute_methods must appear after the # attribute_method_prefix, attribute_method_suffix or # attribute_method_affix declarations. define_attribute_methods :name, :age, :address private def clear_attribute(attr) send("#{attr}=", nil) end end
# File lib/active_model/attribute_methods.rb, line 251 def define_attribute_methods(*attr_names) attr_names.flatten.each { |attr_name| define_attribute_method(attr_name) } end
Removes all the previously dynamically defined methods from the class.
class Person include ActiveModel::AttributeMethods attr_accessor :name attribute_method_suffix '_short?' define_attribute_method :name private def attribute_short?(attr) send(attr).length < 5 end end person = Person.new person.name = 'Bob' person.name_short? # => true Person.undefine_attribute_methods person.name_short? # => NoMethodError
# File lib/active_model/attribute_methods.rb, line 324 def undefine_attribute_methods generated_attribute_methods.module_eval do instance_methods.each { |m| undef_method(m) } end attribute_method_matchers_cache.clear end
Private Instance Methods
The methods method_missing
and respond_to?
of
this module are invoked often in a typical rails, both of which invoke the
method matched_attribute_method
. The latter method iterates
through an array doing regular expression matches, which results in a lot
of object creations. Most of the time it returns a nil
match.
As the match result is always the same given a method_name
,
this cache is used to alleviate the GC, which ultimately also speeds up the
app significantly (in our case our test suite finishes 10% faster with this
cache).
# File lib/active_model/attribute_methods.rb, line 351 def attribute_method_matchers_cache @attribute_method_matchers_cache ||= Concurrent::Map.new(initial_capacity: 4) end
# File lib/active_model/attribute_methods.rb, line 355 def attribute_method_matchers_matching(method_name) attribute_method_matchers_cache.compute_if_absent(method_name) do # Must try to match prefixes/suffixes first, or else the matcher with no prefix/suffix # will match every time. matchers = attribute_method_matchers.partition(&:plain?).reverse.flatten(1) matchers.map { |method| method.match(method_name) }.compact end end
Define a method `name` in `mod` that dispatches to `send` using the given `extra` args. This falls back on `define_method` and `send` if the given names cannot be compiled.
# File lib/active_model/attribute_methods.rb, line 367 def define_proxy_call(include_private, mod, name, send, *extra) defn = if NAME_COMPILABLE_REGEXP.match?(name) "def #{name}(*args)" else "define_method(:'#{name}') do |*args|" end extra = (extra.map!(&:inspect) << "*args").join(", ".freeze) target = if CALL_COMPILABLE_REGEXP.match?(send) "#{"self." unless include_private}#{send}(#{extra})" else "send(:'#{send}', #{extra})" end mod.module_eval " #{defn} #{target} end ", __FILE__, __LINE__ + 1 end
# File lib/active_model/attribute_methods.rb, line 338 def instance_method_already_implemented?(method_name) generated_attribute_methods.method_defined?(method_name) end