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author | Olli Jokinen <olli.jokinen@enemy.fi> | 2011-12-01 15:32:59 +0200 |
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committer | Olli Jokinen <olli.jokinen@enemy.fi> | 2011-12-01 15:32:59 +0200 |
commit | b4e1903d23a760028d58bc3bb20a1d491bfd4a4b (patch) | |
tree | a40bdce1bd4800124ab6eaed2a6be017bf9cfd3d /activerecord/lib/active_record/attribute_methods/serialization.rb | |
parent | fae9ad9c712decef70b379f5aa1faa0149902831 (diff) | |
parent | 1e51cd957e3c90f4be35f1f0c4c380d8f7d40d66 (diff) | |
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Merge remote-tracking branch 'upstream/master'
Diffstat (limited to 'activerecord/lib/active_record/attribute_methods/serialization.rb')
-rw-r--r-- | activerecord/lib/active_record/attribute_methods/serialization.rb | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/attribute_methods/serialization.rb b/activerecord/lib/active_record/attribute_methods/serialization.rb new file mode 100644 index 0000000000..d1eb3d5bfc --- /dev/null +++ b/activerecord/lib/active_record/attribute_methods/serialization.rb @@ -0,0 +1,100 @@ +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 define_method_attribute(attr_name) + if serialized_attributes.include?(attr_name) + generated_attribute_methods.module_eval(<<-CODE, __FILE__, __LINE__) + def _#{attr_name} + @attributes['#{attr_name}'].unserialized_value + end + alias #{attr_name} _#{attr_name} + CODE + else + super + end + end + end + + def set_serialized_attributes + self.class.serialized_attributes.each do |key, coder| + if @attributes.key?(key) + @attributes[key] = Attribute.new(coder, @attributes[key], :serialized) + end + end + end + + def type_cast_attribute(column, value) + if column && self.class.serialized_attributes[column.name] + value.unserialized_value + else + super + 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 + end + end +end |