389 lines
15 KiB
Ruby
389 lines
15 KiB
Ruby
module ActiveRecord
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module AttributeMethods #:nodoc:
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DEFAULT_SUFFIXES = %w(= ? _before_type_cast)
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ATTRIBUTE_TYPES_CACHED_BY_DEFAULT = [:datetime, :timestamp, :time, :date]
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def self.included(base)
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base.extend ClassMethods
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base.attribute_method_suffix(*DEFAULT_SUFFIXES)
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base.cattr_accessor :attribute_types_cached_by_default, :instance_writer => false
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base.attribute_types_cached_by_default = ATTRIBUTE_TYPES_CACHED_BY_DEFAULT
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base.cattr_accessor :time_zone_aware_attributes, :instance_writer => false
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base.time_zone_aware_attributes = false
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base.class_inheritable_accessor :skip_time_zone_conversion_for_attributes, :instance_writer => false
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base.skip_time_zone_conversion_for_attributes = []
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end
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# Declare and check for suffixed attribute methods.
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module ClassMethods
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# Declares a method available for all attributes with the given suffix.
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# Uses +method_missing+ and <tt>respond_to?</tt> to rewrite the method
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#
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# #{attr}#{suffix}(*args, &block)
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#
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# to
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#
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# attribute#{suffix}(#{attr}, *args, &block)
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#
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# An <tt>attribute#{suffix}</tt> instance method must exist and accept at least
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# the +attr+ argument.
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#
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# For example:
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#
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# class Person < ActiveRecord::Base
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# attribute_method_suffix '_changed?'
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#
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# private
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# def attribute_changed?(attr)
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# ...
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# end
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# end
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#
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# person = Person.find(1)
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# person.name_changed? # => false
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# person.name = 'Hubert'
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# person.name_changed? # => true
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def attribute_method_suffix(*suffixes)
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attribute_method_suffixes.concat suffixes
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rebuild_attribute_method_regexp
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end
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# Returns MatchData if method_name is an attribute method.
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def match_attribute_method?(method_name)
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rebuild_attribute_method_regexp unless defined?(@@attribute_method_regexp) && @@attribute_method_regexp
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@@attribute_method_regexp.match(method_name)
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end
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# Contains the names of the generated attribute methods.
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def generated_methods #:nodoc:
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@generated_methods ||= Set.new
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end
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def generated_methods?
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!generated_methods.empty?
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end
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# Generates all the attribute related methods for columns in the database
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# accessors, mutators and query methods.
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def define_attribute_methods
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return if generated_methods?
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columns_hash.each do |name, column|
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unless instance_method_already_implemented?(name)
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if self.serialized_attributes[name]
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define_read_method_for_serialized_attribute(name)
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elsif create_time_zone_conversion_attribute?(name, column)
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define_read_method_for_time_zone_conversion(name)
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else
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define_read_method(name.to_sym, name, column)
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end
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end
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unless instance_method_already_implemented?("#{name}=")
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if create_time_zone_conversion_attribute?(name, column)
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define_write_method_for_time_zone_conversion(name)
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else
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define_write_method(name.to_sym)
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end
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end
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unless instance_method_already_implemented?("#{name}?")
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define_question_method(name)
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end
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end
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end
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# Checks whether the method is defined in the model or any of its subclasses
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# that also derive from Active Record. Raises DangerousAttributeError if the
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# method is defined by Active Record though.
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def instance_method_already_implemented?(method_name)
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method_name = method_name.to_s
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return true if method_name =~ /^id(=$|\?$|$)/
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@_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
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@@_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
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raise DangerousAttributeError, "#{method_name} is defined by ActiveRecord" if @@_defined_activerecord_methods.include?(method_name)
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@_defined_class_methods.include?(method_name)
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end
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alias :define_read_methods :define_attribute_methods
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# +cache_attributes+ allows you to declare which converted attribute values should
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# be cached. Usually caching only pays off for attributes with expensive conversion
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# methods, like time related columns (e.g. +created_at+, +updated_at+).
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def cache_attributes(*attribute_names)
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attribute_names.each {|attr| cached_attributes << attr.to_s}
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end
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# Returns the attributes which are cached. By default time related columns
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# with datatype <tt>:datetime, :timestamp, :time, :date</tt> are cached.
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def cached_attributes
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@cached_attributes ||=
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columns.select{|c| attribute_types_cached_by_default.include?(c.type)}.map(&:name).to_set
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end
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# Returns +true+ if the provided attribute is being cached.
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def cache_attribute?(attr_name)
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cached_attributes.include?(attr_name)
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end
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private
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# Suffixes a, ?, c become regexp /(a|\?|c)$/
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def rebuild_attribute_method_regexp
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suffixes = attribute_method_suffixes.map { |s| Regexp.escape(s) }
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@@attribute_method_regexp = /(#{suffixes.join('|')})$/.freeze
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end
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# Default to =, ?, _before_type_cast
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def attribute_method_suffixes
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@@attribute_method_suffixes ||= []
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end
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def create_time_zone_conversion_attribute?(name, column)
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time_zone_aware_attributes && !skip_time_zone_conversion_for_attributes.include?(name.to_sym) && [:datetime, :timestamp].include?(column.type)
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end
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# Define an attribute reader method. Cope with nil column.
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def define_read_method(symbol, attr_name, column)
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cast_code = column.type_cast_code('v') if column
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access_code = cast_code ? "(v=@attributes['#{attr_name}']) && #{cast_code}" : "@attributes['#{attr_name}']"
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unless attr_name.to_s == self.primary_key.to_s
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access_code = access_code.insert(0, "missing_attribute('#{attr_name}', caller) unless @attributes.has_key?('#{attr_name}'); ")
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end
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if cache_attribute?(attr_name)
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access_code = "@attributes_cache['#{attr_name}'] ||= (#{access_code})"
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end
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evaluate_attribute_method attr_name, "def #{symbol}; #{access_code}; end"
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end
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# Define read method for serialized attribute.
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def define_read_method_for_serialized_attribute(attr_name)
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evaluate_attribute_method attr_name, "def #{attr_name}; unserialize_attribute('#{attr_name}'); end"
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end
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# Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
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# This enhanced read method automatically converts the UTC time stored in the database to the time zone stored in Time.zone.
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def define_read_method_for_time_zone_conversion(attr_name)
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method_body = <<-EOV
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def #{attr_name}(reload = false)
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cached = @attributes_cache['#{attr_name}']
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return cached if cached && !reload
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time = read_attribute('#{attr_name}')
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@attributes_cache['#{attr_name}'] = time.acts_like?(:time) ? time.in_time_zone : time
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end
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EOV
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evaluate_attribute_method attr_name, method_body
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end
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# Defines a predicate method <tt>attr_name?</tt>.
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def define_question_method(attr_name)
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evaluate_attribute_method attr_name, "def #{attr_name}?; query_attribute('#{attr_name}'); end", "#{attr_name}?"
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end
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def define_write_method(attr_name)
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evaluate_attribute_method attr_name, "def #{attr_name}=(new_value);write_attribute('#{attr_name}', new_value);end", "#{attr_name}="
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end
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# Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
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# This enhanced write method will automatically convert the time passed to it to the zone stored in Time.zone.
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def define_write_method_for_time_zone_conversion(attr_name)
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method_body = <<-EOV
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def #{attr_name}=(time)
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unless time.acts_like?(:time)
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time = time.is_a?(String) ? Time.zone.parse(time) : time.to_time rescue time
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end
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time = time.in_time_zone rescue nil if time
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write_attribute(:#{attr_name}, time)
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end
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EOV
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evaluate_attribute_method attr_name, method_body, "#{attr_name}="
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end
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# Evaluate the definition for an attribute related method
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def evaluate_attribute_method(attr_name, method_definition, method_name=attr_name)
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unless method_name.to_s == primary_key.to_s
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generated_methods << method_name
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end
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begin
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class_eval(method_definition, __FILE__, __LINE__)
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rescue SyntaxError => err
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generated_methods.delete(attr_name)
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if logger
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logger.warn "Exception occurred during reader method compilation."
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logger.warn "Maybe #{attr_name} is not a valid Ruby identifier?"
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logger.warn err.message
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end
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end
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end
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end # ClassMethods
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# Allows access to the object attributes, which are held in the <tt>@attributes</tt> hash, as though they
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# were first-class methods. So a Person class with a name attribute can use Person#name and
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# Person#name= and never directly use the attributes hash -- except for multiple assigns with
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# ActiveRecord#attributes=. A Milestone class can also ask Milestone#completed? to test that
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# the completed attribute is not +nil+ or 0.
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#
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# It's also possible to instantiate related objects, so a Client class belonging to the clients
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# table with a +master_id+ foreign key can instantiate master through Client#master.
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def method_missing(method_id, *args, &block)
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method_name = method_id.to_s
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if self.class.private_method_defined?(method_name)
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raise NoMethodError.new("Attempt to call private method", method_name, args)
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end
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# If we haven't generated any methods yet, generate them, then
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# see if we've created the method we're looking for.
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if !self.class.generated_methods?
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self.class.define_attribute_methods
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if self.class.generated_methods.include?(method_name)
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return self.send(method_id, *args, &block)
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end
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end
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if self.class.primary_key.to_s == method_name
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id
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elsif md = self.class.match_attribute_method?(method_name)
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attribute_name, method_type = md.pre_match, md.to_s
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if @attributes.include?(attribute_name)
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__send__("attribute#{method_type}", attribute_name, *args, &block)
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else
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super
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end
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elsif @attributes.include?(method_name)
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read_attribute(method_name)
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else
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super
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end
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end
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# Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
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# "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)).
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def read_attribute(attr_name)
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attr_name = attr_name.to_s
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if !(value = @attributes[attr_name]).nil?
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if column = column_for_attribute(attr_name)
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if unserializable_attribute?(attr_name, column)
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unserialize_attribute(attr_name)
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else
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column.type_cast(value)
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end
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else
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value
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end
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else
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nil
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end
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end
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def read_attribute_before_type_cast(attr_name)
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@attributes[attr_name]
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end
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# Returns true if the attribute is of a text column and marked for serialization.
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def unserializable_attribute?(attr_name, column)
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column.text? && self.class.serialized_attributes[attr_name]
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end
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# Returns the unserialized object of the attribute.
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def unserialize_attribute(attr_name)
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unserialized_object = object_from_yaml(@attributes[attr_name])
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if unserialized_object.is_a?(self.class.serialized_attributes[attr_name]) || unserialized_object.nil?
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@attributes.frozen? ? unserialized_object : @attributes[attr_name] = unserialized_object
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else
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raise SerializationTypeMismatch,
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"#{attr_name} was supposed to be a #{self.class.serialized_attributes[attr_name]}, but was a #{unserialized_object.class.to_s}"
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end
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end
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# Updates the attribute identified by <tt>attr_name</tt> with the specified +value+. Empty strings for fixnum and float
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# columns are turned into +nil+.
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def write_attribute(attr_name, value)
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attr_name = attr_name.to_s
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@attributes_cache.delete(attr_name)
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if (column = column_for_attribute(attr_name)) && column.number?
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@attributes[attr_name] = convert_number_column_value(value)
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else
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@attributes[attr_name] = value
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end
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end
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def query_attribute(attr_name)
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unless value = read_attribute(attr_name)
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false
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else
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column = self.class.columns_hash[attr_name]
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if column.nil?
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if Numeric === value || value !~ /[^0-9]/
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!value.to_i.zero?
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else
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return false if ActiveRecord::ConnectionAdapters::Column::FALSE_VALUES.include?(value)
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!value.blank?
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end
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elsif column.number?
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!value.zero?
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else
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!value.blank?
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end
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end
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end
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# A Person object with a name attribute can ask <tt>person.respond_to?(:name)</tt>,
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# <tt>person.respond_to?(:name=)</tt>, and <tt>person.respond_to?(:name?)</tt>
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# which will all return +true+.
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alias :respond_to_without_attributes? :respond_to?
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def respond_to?(method, include_private_methods = false)
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method_name = method.to_s
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if super
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return true
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elsif !include_private_methods && super(method, true)
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# If we're here than we haven't found among non-private methods
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# but found among all methods. Which means that given method is private.
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return false
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elsif !self.class.generated_methods?
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self.class.define_attribute_methods
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if self.class.generated_methods.include?(method_name)
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return true
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end
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end
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if @attributes.nil?
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return super
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elsif @attributes.include?(method_name)
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return true
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elsif md = self.class.match_attribute_method?(method_name)
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return true if @attributes.include?(md.pre_match)
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end
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super
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end
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private
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def missing_attribute(attr_name, stack)
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raise ActiveRecord::MissingAttributeError, "missing attribute: #{attr_name}", stack
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end
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# Handle *? for method_missing.
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def attribute?(attribute_name)
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query_attribute(attribute_name)
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end
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# Handle *= for method_missing.
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def attribute=(attribute_name, value)
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write_attribute(attribute_name, value)
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end
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# Handle *_before_type_cast for method_missing.
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def attribute_before_type_cast(attribute_name)
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read_attribute_before_type_cast(attribute_name)
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end
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end
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end
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