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Diffstat (limited to 'activerecord/lib/active_record/attributes.rb')
| -rw-r--r-- | activerecord/lib/active_record/attributes.rb | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/attributes.rb b/activerecord/lib/active_record/attributes.rb new file mode 100644 index 0000000000..9c80121d70 --- /dev/null +++ b/activerecord/lib/active_record/attributes.rb @@ -0,0 +1,122 @@ +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 |