module ActiveRecord::AttributeMethods::Serialization::ClassMethods
Public Instance Methods
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.
A notable side effect of serialized attributes is that the model will be updated on every save, even if it is not dirty.
Parameters¶ ↑
-
attr_name
- The field name that should be serialized. -
class_name_or_coder
- Optional, a coder object, which responds to `.load` / `.dump` or a class name that the object type should be equal to.
Example¶ ↑
# Serialize a preferences attribute. class User < ActiveRecord::Base serialize :preferences end # Serialize preferences using JSON as coder. class User < ActiveRecord::Base serialize :preferences, JSON end # Serialize preferences as Hash using YAML coder. class User < ActiveRecord::Base serialize :preferences, Hash end
# File lib/active_record/attribute_methods/serialization.rb, line 52 def serialize(attr_name, class_name_or_coder = Object) include Behavior coder = if [:load, :dump].all? { |x| class_name_or_coder.respond_to?(x) } class_name_or_coder else Coders::YAMLColumn.new(class_name_or_coder) 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
Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.
# File lib/active_record/attribute_methods/serialization.rb, line 20