module ActiveRecord module AttributeMethods #:nodoc: DEFAULT_SUFFIXES = %w(= ? _before_type_cast) ATTRIBUTE_TYPES_CACHED_BY_DEFAULT = [:datetime, :timestamp, :time, :date] def self.included(base) base.extend ClassMethods base.attribute_method_suffix *DEFAULT_SUFFIXES base.cattr_accessor :attribute_types_cached_by_default, :instance_writer => false base.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT end # Declare and check for suffixed attribute methods. module ClassMethods # Declare 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 '_changed?' # # private # def attribute_changed?(attr) # ... # end # end # # person = Person.find(1) # person.name_changed? # => false # person.name = 'Hubert' # person.name_changed? # => true def attribute_method_suffix(*suffixes) attribute_method_suffixes.concat suffixes rebuild_attribute_method_regexp end # Returns MatchData if method_name is an attribute method. def match_attribute_method?(method_name) rebuild_attribute_method_regexp unless defined?(@@attribute_method_regexp) && @@attribute_method_regexp @@attribute_method_regexp.match(method_name) end # Contains the names of the generated attribute methods. def generated_methods #:nodoc: @generated_methods ||= Set.new end def generated_methods? !generated_methods.empty? end # generates all the attribute related methods for columns in the database # accessors, mutators and query methods def define_attribute_methods return if generated_methods? columns_hash.each do |name, column| unless instance_method_already_implemented?(name) if self.serialized_attributes[name] define_read_method_for_serialized_attribute(name) else define_read_method(name.to_sym, name, column) end end unless instance_method_already_implemented?("#{name}=") define_write_method(name.to_sym) end unless instance_method_already_implemented?("#{name}?") define_question_method(name) end end end # Check to see if the method is defined in the model or any of it's subclasses that also derive from ActiveRecord. # Raise DangerousAttributeError if the method is defined by ActiveRecord though. def instance_method_already_implemented?(method_name) return true if method_name =~ /^id(=$|\?$|$)/ @_defined_class_methods ||= Set.new(ancestors.first(ancestors.index(ActiveRecord::Base)).collect! { |m| m.public_instance_methods(false) | m.private_instance_methods(false) | m.protected_instance_methods(false) }.flatten) @@_defined_activerecord_methods ||= Set.new(ActiveRecord::Base.public_instance_methods(false) | ActiveRecord::Base.private_instance_methods(false) | ActiveRecord::Base.protected_instance_methods(false)) raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord" if @@_defined_activerecord_methods.include?(method_name) @_defined_class_methods.include?(method_name) end alias :define_read_methods :define_attribute_methods # +cache_attributes+ allows you to declare which converted attribute values should # be cached. Usually caching only pays off for attributes with expensive conversion # methods, like date columns (e.g. created_at, updated_at). def cache_attributes(*attribute_names) attribute_names.each {|attr| cached_attributes << attr.to_s} end # returns the attributes where def cached_attributes @cached_attributes ||= columns.select{|c| attribute_types_cached_by_default.include?(c.type)}.map(&:name).to_set end def cache_attribute?(attr_name) cached_attributes.include?(attr_name) end private # Suffixes a, ?, c become regexp /(a|\?|c)$/ def rebuild_attribute_method_regexp suffixes = attribute_method_suffixes.map { |s| Regexp.escape(s) } @@attribute_method_regexp = /(#{suffixes.join('|')})$/.freeze end # Default to =, ?, _before_type_cast def attribute_method_suffixes @@attribute_method_suffixes ||= [] end # Define an attribute reader method. Cope with nil column. def define_read_method(symbol, attr_name, column) cast_code = column.type_cast_code('v') if column access_code = cast_code ? "(v=@attributes['#{attr_name}']) && #{cast_code}" : "@attributes['#{attr_name}']" unless attr_name.to_s == self.primary_key.to_s access_code = access_code.insert(0, "missing_attribute('#{attr_name}', caller) unless @attributes.has_key?('#{attr_name}'); ") end if cache_attribute?(attr_name) access_code = "@attributes_cache['#{attr_name}'] ||= (#{access_code})" end evaluate_attribute_method attr_name, "def #{symbol}; #{access_code}; end" end # Define read method for serialized attribute. def define_read_method_for_serialized_attribute(attr_name) evaluate_attribute_method attr_name, "def #{attr_name}; unserialize_attribute('#{attr_name}'); end" end # Define an attribute ? method. def define_question_method(attr_name) evaluate_attribute_method attr_name, "def #{attr_name}?; query_attribute('#{attr_name}'); end", "#{attr_name}?" end def define_write_method(attr_name) evaluate_attribute_method attr_name, "def #{attr_name}=(new_value);write_attribute('#{attr_name}', new_value);end", "#{attr_name}=" end # Evaluate the definition for an attribute related method def evaluate_attribute_method(attr_name, method_definition, method_name=attr_name) unless method_name.to_s == primary_key.to_s generated_methods << method_name end begin class_eval(method_definition, __FILE__, __LINE__) rescue SyntaxError => err generated_methods.delete(attr_name) if logger logger.warn "Exception occurred during reader method compilation." logger.warn "Maybe #{attr_name} is not a valid Ruby identifier?" logger.warn "#{err.message}" end end end end # ClassMethods # 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? self.class.define_attribute_methods if self.class.generated_methods.include?(method_name) return self.send(method_id, *args, &block) end end if self.class.primary_key.to_s == method_name id elsif md = self.class.match_attribute_method?(method_name) attribute_name, method_type = md.pre_match, md.to_s if @attributes.include?(attribute_name) __send__("attribute#{method_type}", attribute_name, *args, &block) else super end elsif @attributes.include?(method_name) read_attribute(method_name) else super end end # Returns the value of the attribute identified by attr_name after it has been typecast (for example, # "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)). def read_attribute(attr_name) attr_name = attr_name.to_s if !(value = @attributes[attr_name]).nil? if column = column_for_attribute(attr_name) if unserializable_attribute?(attr_name, column) unserialize_attribute(attr_name) else column.type_cast(value) end else value end else nil end end def read_attribute_before_type_cast(attr_name) @attributes[attr_name] end # Returns true if the attribute is of a text column and marked for serialization. def unserializable_attribute?(attr_name, column) column.text? && self.class.serialized_attributes[attr_name] end # Returns the unserialized object of the attribute. def unserialize_attribute(attr_name) unserialized_object = object_from_yaml(@attributes[attr_name]) if unserialized_object.is_a?(self.class.serialized_attributes[attr_name]) || unserialized_object.nil? @attributes.frozen? ? unserialized_object : @attributes[attr_name] = unserialized_object else raise SerializationTypeMismatch, "#{attr_name} was supposed to be a #{self.class.serialized_attributes[attr_name]}, but was a #{unserialized_object.class.to_s}" end end # Updates the attribute identified by attr_name with the specified +value+. Empty strings for fixnum and float # columns are turned into nil. def write_attribute(attr_name, value) attr_name = attr_name.to_s @attributes_cache.delete(attr_name) if (column = column_for_attribute(attr_name)) && column.number? @attributes[attr_name] = convert_number_column_value(value) else @attributes[attr_name] = value end end def query_attribute(attr_name) unless value = read_attribute(attr_name) false else column = self.class.columns_hash[attr_name] if column.nil? if Numeric === value || value !~ /[^0-9]/ !value.to_i.zero? else !value.blank? end elsif column.number? !value.zero? else !value.blank? end end 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_priv = false) method_name = method.to_s if super return true elsif !self.class.generated_methods? self.class.define_attribute_methods if self.class.generated_methods.include?(method_name) return true end end if @attributes.nil? return super elsif @attributes.include?(method_name) return true elsif md = self.class.match_attribute_method?(method_name) return true if @attributes.include?(md.pre_match) end super end private def missing_attribute(attr_name, stack) raise ActiveRecord::MissingAttributeError, "missing attribute: #{attr_name}", stack end # Handle *? for method_missing. def attribute?(attribute_name) query_attribute(attribute_name) end # Handle *= for method_missing. def attribute=(attribute_name, value) write_attribute(attribute_name, value) end # Handle *_before_type_cast for method_missing. def attribute_before_type_cast(attribute_name) read_attribute_before_type_cast(attribute_name) end end end