lib/active_model/attribute_methods.rb in activemodel-3.0.pre vs lib/active_model/attribute_methods.rb in activemodel-3.0.0.rc

- old
+ new

@@ -2,43 +2,112 @@ require 'active_support/core_ext/class/inheritable_attributes' module ActiveModel class MissingAttributeError < NoMethodError end - + # == Active Model Attribute Methods + # + # <tt>ActiveModel::AttributeMethods</tt> 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: + # + # * <tt>include ActiveModel::AttributeMethods</tt> in your object + # * Call each Attribute Method module method you want to add, such as + # attribute_method_suffix or attribute_method_prefix + # * Call <tt>define_attribute_methods</tt> 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 <tt>attributes</tt> 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. + # module AttributeMethods extend ActiveSupport::Concern - # Declare and check for suffixed attribute methods. module ClassMethods - # Defines an "attribute" method (like +inheritance_column+ or - # +table_name+). A new (class) method will be created with the - # given name. If a value is specified, the new method will - # return that value (as a string). Otherwise, the given block - # will be used to compute the value of the method. + # Defines an "attribute" method (like +inheritance_column+ or +table_name+). + # A new (class) method will be created with the given name. If a value is + # specified, the new method will return that value (as a string). + # Otherwise, the given block will be used to compute the value of the + # method. # - # The original method will be aliased, with the new name being - # prefixed with "original_". This allows the new method to - # access the original value. + # The original method will be aliased, with the new name being prefixed + # with "original_". This allows the new method to access the original + # value. # # Example: # - # class A < ActiveRecord::Base + # class Person + # + # include ActiveModel::AttributeMethods + # + # cattr_accessor :primary_key + # cattr_accessor :inheritance_column + # # define_attr_method :primary_key, "sysid" # define_attr_method( :inheritance_column ) do # original_inheritance_column + "_id" # end + # # end + # + # Provides you with: + # + # AttributePerson.primary_key + # # => "sysid" + # AttributePerson.inheritance_column = 'address' + # AttributePerson.inheritance_column + # # => 'address_id' def define_attr_method(name, value=nil, &block) - sing = metaclass - sing.send :alias_method, "original_#{name}", name + sing = singleton_class + sing.class_eval <<-eorb, __FILE__, __LINE__ + 1 + if method_defined?(:original_#{name}) + undef :original_#{name} + end + alias_method :original_#{name}, :#{name} + eorb if block_given? sing.send :define_method, name, &block else # use eval instead of a block to work around a memory leak in dev # mode in fcgi - sing.class_eval "def #{name}; #{value.to_s.inspect}; end" + sing.class_eval <<-eorb, __FILE__, __LINE__ + 1 + def #{name}; #{value.to_s.inspect}; end + eorb end end # Declares a method available for all attributes with the given prefix. # Uses +method_missing+ and <tt>respond_to?</tt> to rewrite the method. @@ -47,28 +116,34 @@ # # to # # #{prefix}attribute(#{attr}, *args, &block) # - # An <tt>#{prefix}attribute</tt> instance method must exist and accept at least - # the +attr+ argument. + # An instance method <tt>#{prefix}attribute</tt> must exist and accept + # at least the +attr+ argument. # # For example: # - # class Person < ActiveRecord::Base + # class Person + # + # include ActiveModel::AttributeMethods + # attr_accessor :name # attribute_method_prefix 'clear_' + # define_attribute_methods [:name] # # private - # def clear_attribute(attr) - # ... - # end + # + # def clear_attribute(attr) + # send("#{attr}=", nil) + # end # end # - # person = Person.find(1) - # person.name # => 'Gem' + # person = Person.new + # person.name = "Bob" + # person.name # => "Bob" # person.clear_name - # person.name # => '' + # person.name # => nil def attribute_method_prefix(*prefixes) attribute_method_matchers.concat(prefixes.map { |prefix| AttributeMethodMatcher.new :prefix => prefix }) undefine_attribute_methods end @@ -84,22 +159,28 @@ # An <tt>attribute#{suffix}</tt> instance method must exist and accept at least # the +attr+ argument. # # For example: # - # class Person < ActiveRecord::Base + # class Person + # + # include ActiveModel::AttributeMethods + # attr_accessor :name # attribute_method_suffix '_short?' + # define_attribute_methods [:name] # # private - # def attribute_short?(attr) - # ... - # end + # + # def attribute_short?(attr) + # send(attr).length < 5 + # end # end # - # person = Person.find(1) - # person.name # => 'Gem' - # person.name_short? # => true + # person = Person.new + # person.name = "Bob" + # person.name # => "Bob" + # person.name_short? # => true def attribute_method_suffix(*suffixes) attribute_method_matchers.concat(suffixes.map { |suffix| AttributeMethodMatcher.new :suffix => suffix }) undefine_attribute_methods end @@ -116,75 +197,112 @@ # An <tt>#{prefix}attribute#{suffix}</tt> instance method must exist and # accept at least the +attr+ argument. # # For example: # - # class Person < ActiveRecord::Base + # 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) - # ... - # end + # + # def reset_attribute_to_default!(attr) + # ... + # end # end # - # person = Person.find(1) + # person = Person.new # person.name # => 'Gem' # person.reset_name_to_default! # person.name # => 'Gemma' def attribute_method_affix(*affixes) attribute_method_matchers.concat(affixes.map { |affix| AttributeMethodMatcher.new :prefix => affix[:prefix], :suffix => affix[:suffix] }) undefine_attribute_methods end def alias_attribute(new_name, old_name) attribute_method_matchers.each do |matcher| - module_eval <<-STR, __FILE__, __LINE__+1 + module_eval <<-STR, __FILE__, __LINE__ + 1 def #{matcher.method_name(new_name)}(*args) send(:#{matcher.method_name(old_name)}, *args) end STR end end + # Declares a the attributes that should be prefixed and suffixed by + # ActiveModel::AttributeMethods. + # + # To use, pass in an array of 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 declares. + # define_attribute_methods [:name, :age, :address] + # + # private + # + # def clear_attribute(attr) + # ... + # end + # end def define_attribute_methods(attr_names) return if attribute_methods_generated? attr_names.each do |attr_name| attribute_method_matchers.each do |matcher| unless instance_method_already_implemented?(matcher.method_name(attr_name)) generate_method = "define_method_#{matcher.prefix}attribute#{matcher.suffix}" if respond_to?(generate_method) send(generate_method, attr_name) else - generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__+1 - def #{matcher.method_name(attr_name)}(*args) + method_name = matcher.method_name(attr_name) + + generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1 + if method_defined?(:#{method_name}) + undef :#{method_name} + end + def #{method_name}(*args) send(:#{matcher.method_missing_target}, '#{attr_name}', *args) end STR end end end end @attribute_methods_generated = true end + # Removes all the preiously dynamically defined methods from the class def undefine_attribute_methods generated_attribute_methods.module_eval do instance_methods.each { |m| undef_method(m) } end @attribute_methods_generated = nil end + # Returns true if the attribute methods defined have been generated. def generated_attribute_methods #:nodoc: @generated_attribute_methods ||= begin mod = Module.new include mod mod end end + # Returns true if the attribute methods defined have been generated. def attribute_methods_generated? @attribute_methods_generated ||= nil end protected @@ -224,18 +342,21 @@ def attribute_method_matchers #:nodoc: read_inheritable_attribute(:attribute_method_matchers) || write_inheritable_attribute(:attribute_method_matchers, []) end end - # Allows access to the object attributes, which are held in the <tt>@attributes</tt> 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. + # Allows access to the object attributes, which are held in the + # <tt>@attributes</tt> 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. + # 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. 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) @@ -250,10 +371,10 @@ 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 given method is private. + # 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