require 'active_support/core_ext/enumerable'
module ActiveRecord
module AttributeMethods #:nodoc:
extend ActiveSupport::Concern
class AttributeMethodMatcher
attr_reader :prefix, :suffix
AttributeMethodMatch = Struct.new(:prefix, :base, :suffix)
def initialize(options = {})
options.symbolize_keys!
@prefix, @suffix = options[:prefix] || '', options[:suffix] || ''
@regex = /^(#{Regexp.escape(@prefix)})(.+?)(#{Regexp.escape(@suffix)})$/
end
def match(method_name)
if matchdata = @regex.match(method_name)
AttributeMethodMatch.new(matchdata[1], matchdata[2], matchdata[3])
else
nil
end
end
end
# Declare and check for suffixed attribute methods.
module ClassMethods
# 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 #{prefix}attribute instance method must exist and accept at least
# the +attr+ argument.
#
# For example:
#
# class Person < ActiveRecord::Base
# attribute_method_prefix 'clear_'
#
# private
# def clear_attribute(attr)
# ...
# end
# end
#
# person = Person.find(1)
# person.name # => 'Gem'
# person.clear_name
# person.name # => ''
def attribute_method_prefix(*prefixes)
attribute_method_matchers.concat(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.
#
# For example:
#
# class Person < ActiveRecord::Base
# attribute_method_suffix '_short?'
#
# private
# def attribute_short?(attr)
# ...
# end
# end
#
# person = Person.find(1)
# person.name # => 'Gem'
# person.name_short? # => true
def attribute_method_suffix(*suffixes)
attribute_method_matchers.concat(suffixes.map { |suffix| AttributeMethodMatcher.new :suffix => suffix })
undefine_attribute_methods
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.
#
# For example:
#
# class Person < ActiveRecord::Base
# attribute_method_affix :prefix => 'reset_', :suffix => '_to_default!'
#
# private
# def reset_attribute_to_default!(attr)
# ...
# end
# end
#
# person = Person.find(1)
# 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 matching_attribute_methods(method_name)
attribute_method_matchers.collect { |method| method.match(method_name) }.compact
end
# 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.
#
# Example:
#
# class A < ActiveRecord::Base
# define_attr_method :primary_key, "sysid"
# define_attr_method( :inheritance_column ) do
# original_inheritance_column + "_id"
# end
# end
def define_attr_method(name, value=nil, &block)
sing = metaclass
sing.send :alias_method, "original_#{name}", name
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"
end
end
def generated_methods #:nodoc:
@generated_methods ||= begin
mod = Module.new
include mod
mod
end
end
# Generates all the attribute related methods for columns in the database
# accessors, mutators and query methods.
def define_attribute_methods
return unless generated_methods.instance_methods.empty?
columns_hash.keys.each do |name|
attribute_method_matchers.each do |method|
method_name = "#{method.prefix}#{name}#{method.suffix}"
unless instance_method_already_implemented?(method_name)
generate_method = "define_method_#{method.prefix}attribute#{method.suffix}"
if respond_to?(generate_method)
send(generate_method, name)
else
generated_methods.module_eval("def #{method_name}(*args); send(:#{method.prefix}attribute#{method.suffix}, '#{name}', *args); end", __FILE__, __LINE__)
end
end
end
end
end
def undefine_attribute_methods
generated_methods.module_eval do
instance_methods.each { |m| undef_method(m) }
end
end
# Checks whether the method is defined in the model or any of its subclasses
# that also derive from Active Record. Raises DangerousAttributeError if the
# method is defined by Active Record though.
def instance_method_already_implemented?(method_name)
method_name = method_name.to_s
@_defined_class_methods ||= ancestors.first(ancestors.index(ActiveRecord::Base)).sum([]) { |m| m.public_instance_methods(false) | m.private_instance_methods(false) | m.protected_instance_methods(false) }.map {|m| m.to_s }.to_set
@@_defined_activerecord_methods ||= (ActiveRecord::Base.public_instance_methods(false) | ActiveRecord::Base.private_instance_methods(false) | ActiveRecord::Base.protected_instance_methods(false)).map{|m| m.to_s }.to_set
raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord" if @@_defined_activerecord_methods.include?(method_name)
@_defined_class_methods.include?(method_name)
end
private
# Default to *=, *? and *_before_type_cast
def attribute_method_matchers
@@attribute_method_matchers ||= []
end
end
# Returns a struct representing the matching attribute method.
# The struct's attributes are prefix, base and suffix.
def match_attribute_method?(method_name)
self.class.matching_attribute_methods(method_name).find do |match|
match.base == 'id' || @attributes.include?(match.base)
end
end
# 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.
def method_missing(method_id, *args, &block)
method_name = method_id.to_s
# If we haven't generated any methods yet, generate them, then
# see if we've created the method we're looking for.
if self.class.generated_methods.instance_methods.empty?
self.class.define_attribute_methods
guard_private_attribute_method!(method_name, args)
if self.class.generated_methods.instance_methods.include?(method_name)
return self.send(method_id, *args, &block)
end
end
if match = match_attribute_method?(method_name)
guard_private_attribute_method!(method_name, args)
return __send__("#{match.prefix}attribute#{match.suffix}", match.base, *args, &block)
end
super
end
# A Person object with a name attribute can ask person.respond_to?(:name),
# person.respond_to?(:name=), and person.respond_to?(:name?)
# which will all return +true+.
alias :respond_to_without_attributes? :respond_to?
def respond_to?(method, include_private_methods = false)
method_name = method.to_s
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.
return false
elsif self.class.generated_methods.instance_methods.empty?
self.class.define_attribute_methods
if self.class.generated_methods.instance_methods.include?(method_name)
return true
end
elsif match_attribute_method?(method_name)
return true
end
super
end
private
# prevent method_missing from calling private methods with #send
def guard_private_attribute_method!(method_name, args)
if self.class.private_method_defined?(method_name)
raise NoMethodError.new("Attempt to call private method", method_name, args)
end
end
def missing_attribute(attr_name, stack)
raise ActiveRecord::MissingAttributeError, "missing attribute: #{attr_name}", stack
end
end
end