diff options
Diffstat (limited to 'activerecord/lib/active_record/attribute.rb')
-rw-r--r-- | activerecord/lib/active_record/attribute.rb | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/attribute.rb b/activerecord/lib/active_record/attribute.rb new file mode 100644 index 0000000000..8cc1904575 --- /dev/null +++ b/activerecord/lib/active_record/attribute.rb @@ -0,0 +1,131 @@ +module ActiveRecord + class Attribute # :nodoc: + class << self + def from_database(name, value, type) + FromDatabase.new(name, value, type) + end + + def from_user(name, value, type) + FromUser.new(name, value, type) + end + + def null(name) + Null.new(name) + end + + def uninitialized(name, type) + Uninitialized.new(name, type) + end + end + + attr_reader :name, :value_before_type_cast, :type + + # This method should not be called directly. + # Use #from_database or #from_user + def initialize(name, value_before_type_cast, type) + @name = name + @value_before_type_cast = value_before_type_cast + @type = type + end + + def value + # `defined?` is cheaper than `||=` when we get back falsy values + @value = original_value unless defined?(@value) + @value + end + + def original_value + type_cast(value_before_type_cast) + end + + def value_for_database + type.type_cast_for_database(value) + end + + def changed_from?(old_value) + type.changed?(old_value, value, value_before_type_cast) + end + + def changed_in_place_from?(old_value) + type.changed_in_place?(old_value, value) + end + + def with_value_from_user(value) + self.class.from_user(name, value, type) + end + + def with_value_from_database(value) + self.class.from_database(name, value, type) + end + + def type_cast(*) + raise NotImplementedError + end + + def initialized? + true + end + + def ==(other) + self.class == other.class && + name == other.name && + value_before_type_cast == other.value_before_type_cast && + type == other.type + end + + protected + + def initialize_dup(other) + if defined?(@value) && @value.duplicable? + @value = @value.dup + end + end + + class FromDatabase < Attribute # :nodoc: + def type_cast(value) + type.type_cast_from_database(value) + end + end + + class FromUser < Attribute # :nodoc: + def type_cast(value) + type.type_cast_from_user(value) + end + end + + class Null < Attribute # :nodoc: + def initialize(name) + super(name, nil, Type::Value.new) + end + + def value + nil + end + + def with_value_from_database(value) + raise ActiveModel::MissingAttributeError, "can't write unknown attribute `#{name}`" + end + alias_method :with_value_from_user, :with_value_from_database + end + + class Uninitialized < Attribute # :nodoc: + def initialize(name, type) + super(name, nil, type) + end + + def value + if block_given? + yield name + end + end + + def value_for_database + end + + def initialized? + false + end + end + private_constant :FromDatabase, :FromUser, :Null, :Uninitialized + end +end |