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module ActiveRecord
module Attributes # :nodoc:
extend ActiveSupport::Concern
Type = ActiveRecord::Type
included do
class_attribute :user_provided_columns, instance_accessor: false # :internal:
self.user_provided_columns = {}
end
module ClassMethods
# Defines or overrides a 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 overriden.
#
# # 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
clear_caches_calculated_from_columns
# Assign a new hash to ensure that subclasses do not share a hash
self.user_provided_columns = user_provided_columns.merge(name => connection.new_column(name, options[:default], cast_type))
end
# Returns an array of column objects for the table associated with this class.
def columns
@columns ||= add_user_provided_columns(connection.schema_cache.columns(table_name))
end
# Returns a hash of column objects for the table associated with this class.
def columns_hash
@columns_hash ||= Hash[columns.map { |c| [c.name, c] }]
end
def reset_column_information # :nodoc:
super
clear_caches_calculated_from_columns
end
private
def add_user_provided_columns(schema_columns)
existing_columns = schema_columns.map do |column|
user_provided_columns[column.name] || column
end
existing_column_names = existing_columns.map(&:name)
new_columns = user_provided_columns.except(*existing_column_names).values
existing_columns + new_columns
end
def clear_caches_calculated_from_columns
@columns = nil
@columns_hash = nil
@column_types = nil
@column_defaults = nil
@raw_column_defaults = nil
@column_names = nil
@content_columns = nil
end
end
end
end
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