module ActiveRecord
module Attributes # :nodoc:
extend ActiveSupport::Concern
Type = ActiveRecord::Type
included do
class_attribute :attributes_to_define_after_schema_loads, instance_accessor: false # :internal:
self.attributes_to_define_after_schema_loads = {}
end
module ClassMethods # :nodoc:
# Defines or overrides an attribute on this model. This allows customization of
# Active Record's type casting behavior, as well as adding support for user defined
# types.
#
# +name+ The name of the methods to define attribute methods for, and the column which
# this will persist to.
#
# +cast_type+ A type object that contains information about how to type cast the value.
# See the examples section for more information.
#
# ==== Options
# The options hash accepts the following options:
#
# +default+ is the default value that the column should use on a new record.
#
# ==== Examples
#
# The type detected by Active Record can be overridden.
#
# # db/schema.rb
# create_table :store_listings, force: true do |t|
# t.decimal :price_in_cents
# end
#
# # app/models/store_listing.rb
# class StoreListing < ActiveRecord::Base
# end
#
# store_listing = StoreListing.new(price_in_cents: '10.1')
#
# # before
# store_listing.price_in_cents # => BigDecimal.new(10.1)
#
# class StoreListing < ActiveRecord::Base
# attribute :price_in_cents, Type::Integer.new
# end
#
# # after
# store_listing.price_in_cents # => 10
#
# Users may also define their own custom types, as long as they respond to the methods
# defined on the value type. The +type_cast+ method on your type object will be called
# with values both from the database, and from your controllers. See
# +ActiveRecord::Attributes::Type::Value+ for the expected API. It is recommended that your
# type objects inherit from an existing type, or the base value type.
#
# class MoneyType < ActiveRecord::Type::Integer
# def type_cast(value)
# if value.include?('$')
# price_in_dollars = value.gsub(/\$/, '').to_f
# price_in_dollars * 100
# else
# value.to_i
# end
# end
# end
#
# class StoreListing < ActiveRecord::Base
# attribute :price_in_cents, MoneyType.new
# end
#
# store_listing = StoreListing.new(price_in_cents: '$10.00')
# store_listing.price_in_cents # => 1000
def attribute(name, cast_type, **options)
name = name.to_s
reload_schema_from_cache
self.attributes_to_define_after_schema_loads = attributes_to_define_after_schema_loads.merge(name => [cast_type, options])
end
def define_attribute(
name,
cast_type,
default: NO_DEFAULT_PROVIDED,
user_provided_default: true
)
attribute_types[name] = cast_type
define_default_attribute(name, default, cast_type, from_user: user_provided_default)
end
def load_schema!
super
attributes_to_define_after_schema_loads.each do |name, (type, options)|
define_attribute(name, type, **options)
end
end
private
NO_DEFAULT_PROVIDED = Object.new # :nodoc:
private_constant :NO_DEFAULT_PROVIDED
def define_default_attribute(name, value, type, from_user:)
if value == NO_DEFAULT_PROVIDED
default_attribute = _default_attributes[name].with_type(type)
elsif from_user
default_attribute = Attribute.from_user(name, value, type)
else
default_attribute = Attribute.from_database(name, value, type)
end
_default_attributes[name] = default_attribute
end
end
end
end
