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Instance Public methods
alias_attribute(new_name, old_name) Link
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 activemodel/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) CodeGenerator.batch(self, __FILE__, __LINE__) do |owner| 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, owner, matcher_new, matcher_old end end end
attribute_alias(name) Link
Returns the original name for the alias name
attribute_alias?(new_name) Link
Is new_name
an alias?
attribute_method_affix(*affixes) Link
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'
attribute_method_prefix(*prefixes) Link
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
attribute_method_suffix(*suffixes) Link
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
define_attribute_method(attr_name, _owner: generated_attribute_methods) Link
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 activemodel/lib/active_model/attribute_methods.rb, line 288 def define_attribute_method(attr_name, _owner: generated_attribute_methods) CodeGenerator.batch(_owner, __FILE__, __LINE__) do |owner| 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.target}" if respond_to?(generate_method, true) send(generate_method, attr_name.to_s, owner: owner) else define_proxy_call true, owner, method_name, matcher.target, attr_name.to_s end end end attribute_method_matchers_cache.clear end end
define_attribute_methods(*attr_names) Link
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 activemodel/lib/active_model/attribute_methods.rb, line 253 def define_attribute_methods(*attr_names) CodeGenerator.batch(generated_attribute_methods, __FILE__, __LINE__) do |owner| attr_names.flatten.each { |attr_name| define_attribute_method(attr_name, _owner: owner) } end end
undefine_attribute_methods() Link
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