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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
base.cattr_accessor :time_zone_aware_attributes, :instance_writer => false
base.time_zone_aware_attributes = false
base.class_inheritable_accessor :skip_time_zone_conversion_for_attributes, :instance_writer => false
base.skip_time_zone_conversion_for_attributes = []
end
# Declare and check for suffixed attribute methods.
module ClassMethods
# Declares a method available for all attributes with the given suffix.
# Uses +method_missing+ and <tt>respond_to?</tt> to rewrite the method
#
# #{attr}#{suffix}(*args, &block)
#
# to
#
# attribute#{suffix}(#{attr}, *args, &block)
#
# An <tt>attribute#{suffix}</tt> 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)
elsif create_time_zone_conversion_attribute?(name, column)
define_read_method_for_time_zone_conversion(name)
else
define_read_method(name.to_sym, name, column)
end
end
unless instance_method_already_implemented?("#{name}=")
if create_time_zone_conversion_attribute?(name, column)
define_write_method_for_time_zone_conversion(name)
else
define_write_method(name.to_sym)
end
end
unless instance_method_already_implemented?("#{name}?")
define_question_method(name)
end
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
return true if method_name =~ /^id(=$|\?$|$)/
@_defined_class_methods ||= ancestors.first(ancestors.index(ActiveRecord::Base)).sum([]) { |m| m.public_instance_methods(false) | m.private_instance_methods(false) | m.protected_instance_methods(false) }.map(&:to_s).to_set
@@_defined_activerecord_methods ||= (ActiveRecord::Base.public_instance_methods(false) | ActiveRecord::Base.private_instance_methods(false) | ActiveRecord::Base.protected_instance_methods(false)).map(&:to_s).to_set
raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord" if @@_defined_activerecord_methods.include?(method_name)
@_defined_class_methods.include?(method_name)
end
alias :define_read_methods :define_attribute_methods
# +cache_attributes+ allows you to declare which converted attribute values should
# be cached. Usually caching only pays off for attributes with expensive conversion
# methods, like time related columns (e.g. +created_at+, +updated_at+).
def cache_attributes(*attribute_names)
attribute_names.each {|attr| cached_attributes << attr.to_s}
end
# Returns the attributes which are cached. By default time related columns
# with datatype <tt>:datetime, :timestamp, :time, :date</tt> are cached.
def cached_attributes
@cached_attributes ||=
columns.select{|c| attribute_types_cached_by_default.include?(c.type)}.map(&:name).to_set
end
# Returns +true+ if the provided attribute is being cached.
def cache_attribute?(attr_name)
cached_attributes.include?(attr_name)
end
private
# Suffixes a, ?, c become regexp /(a|\?|c)$/
def rebuild_attribute_method_regexp
suffixes = attribute_method_suffixes.map { |s| Regexp.escape(s) }
@@attribute_method_regexp = /(#{suffixes.join('|')})\z/.freeze
end
# Default to =, ?, _before_type_cast
def attribute_method_suffixes
@@attribute_method_suffixes ||= []
end
def create_time_zone_conversion_attribute?(name, column)
time_zone_aware_attributes && !skip_time_zone_conversion_for_attributes.include?(name.to_sym) && [:datetime, :timestamp].include?(column.type)
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
# Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
# This enhanced read method automatically converts the UTC time stored in the database to the time zone stored in Time.zone.
def define_read_method_for_time_zone_conversion(attr_name)
method_body = <<-EOV
def #{attr_name}(reload = false)
cached = @attributes_cache['#{attr_name}']
return cached if cached && !reload
time = read_attribute('#{attr_name}')
@attributes_cache['#{attr_name}'] = time.acts_like?(:time) ? time.in_time_zone : time
end
EOV
evaluate_attribute_method attr_name, method_body
end
# Defines a predicate method <tt>attr_name?</tt>.
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
# Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
# This enhanced write method will automatically convert the time passed to it to the zone stored in Time.zone.
def define_write_method_for_time_zone_conversion(attr_name)
method_body = <<-EOV
def #{attr_name}=(time)
unless time.acts_like?(:time)
time = time.is_a?(String) ? Time.zone.parse(time) : time.to_time rescue time
end
time = time.in_time_zone rescue nil if time
write_attribute(:#{attr_name}, time)
end
EOV
evaluate_attribute_method attr_name, method_body, "#{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__)
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 <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.
def method_missing(method_id, *args, &block)
method_name = method_id.to_s
if self.class.private_method_defined?(method_name)
raise NoMethodError.new("Attempt to call private method", method_name, args)
end
# 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 <tt>attr_name</tt> 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 <tt>attr_name</tt> 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
return false if ActiveRecord::ConnectionAdapters::Column::FALSE_VALUES.include?(value)
!value.blank?
end
elsif column.number?
!value.zero?
else
!value.blank?
end
end
end
# A Person object with a name attribute can ask <tt>person.respond_to?(:name)</tt>,
# <tt>person.respond_to?(:name=)</tt>, and <tt>person.respond_to?(:name?)</tt>
# 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 than 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?
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
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