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- module ActiveRecord
- module AttributeMethods
- module Serialization
- extend ActiveSupport::Concern
- included do
- # Returns a hash of all the attributes that have been specified for serialization as
- # keys and their class restriction as values.
- class_attribute :serialized_attributes
- self.serialized_attributes = {}
- end
- class Attribute < Struct.new(:coder, :value, :state)
- def unserialized_value
- state == :serialized ? unserialize : value
- end
- def serialized_value
- state == :unserialized ? serialize : value
- end
- def unserialize
- self.state = :unserialized
- self.value = coder.load(value)
- end
- def serialize
- self.state = :serialized
- self.value = coder.dump(value)
- end
- end
- module ClassMethods
- # If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object,
- # then specify the name of that attribute using this method and it will be handled automatically.
- # The serialization is done through YAML. If +class_name+ is specified, the serialized object must be of that
- # class on retrieval or SerializationTypeMismatch will be raised.
- #
- # ==== Parameters
- #
- # * +attr_name+ - The field name that should be serialized.
- # * +class_name+ - Optional, class name that the object type should be equal to.
- #
- # ==== Example
- # # Serialize a preferences attribute
- # class User < ActiveRecord::Base
- # serialize :preferences
- # end
- def serialize(attr_name, class_name = Object)
- coder = if [:load, :dump].all? { |x| class_name.respond_to?(x) }
- class_name
- else
- Coders::YAMLColumn.new(class_name)
- end
- # merge new serialized attribute and create new hash to ensure that each class in inheritance hierarchy
- # has its own hash of own serialized attributes
- self.serialized_attributes = serialized_attributes.merge(attr_name.to_s => coder)
- end
- def initialize_attributes(attributes, options = {}) #:nodoc:
- serialized = (options.delete(:serialized) { true }) ? :serialized : :unserialized
- super(attributes, options)
- serialized_attributes.each do |key, coder|
- if attributes.key?(key)
- attributes[key] = Attribute.new(coder, attributes[key], serialized)
- end
- end
- attributes
- end
- private
- def attribute_cast_code(attr_name)
- if serialized_attributes.include?(attr_name)
- "v.unserialized_value"
- else
- super
- end
- end
- end
- def type_cast_attribute_for_write(column, value)
- if column && coder = self.class.serialized_attributes[column.name]
- Attribute.new(coder, value, :unserialized)
- else
- super
- end
- end
- def _field_changed?(attr, old, value)
- if self.class.serialized_attributes.include?(attr)
- old != value
- else
- super
- end
- end
- def read_attribute_before_type_cast(attr_name)
- if serialized_attributes.include?(attr_name)
- super.unserialized_value
- else
- super
- end
- end
- def attributes_before_type_cast
- super.dup.tap do |attributes|
- self.class.serialized_attributes.each_key do |key|
- if attributes.key?(key)
- attributes[key] = attributes[key].unserialized_value
- end
- end
- end
- end
- end
- end
- end
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