diff options
Diffstat (limited to 'activemodel/lib/active_model/attribute.rb')
| -rw-r--r-- | activemodel/lib/active_model/attribute.rb | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/attribute.rb b/activemodel/lib/active_model/attribute.rb new file mode 100644 index 0000000000..b75ff80b31 --- /dev/null +++ b/activemodel/lib/active_model/attribute.rb @@ -0,0 +1,243 @@ +# frozen_string_literal: true + +require "active_support/core_ext/object/duplicable" + +module ActiveModel + class Attribute # :nodoc: + class << self + def from_database(name, value, type) + FromDatabase.new(name, value, type) + end + + def from_user(name, value, type, original_attribute = nil) + FromUser.new(name, value, type, original_attribute) + end + + def with_cast_value(name, value, type) + WithCastValue.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, original_attribute = nil) + @name = name + @value_before_type_cast = value_before_type_cast + @type = type + @original_attribute = original_attribute + end + + def value + # `defined?` is cheaper than `||=` when we get back falsy values + @value = type_cast(value_before_type_cast) unless defined?(@value) + @value + end + + def original_value + if assigned? + original_attribute.original_value + else + type_cast(value_before_type_cast) + end + end + + def value_for_database + type.serialize(value) + end + + def changed? + changed_from_assignment? || changed_in_place? + end + + def changed_in_place? + has_been_read? && type.changed_in_place?(original_value_for_database, value) + end + + def forgetting_assignment + with_value_from_database(value_for_database) + end + + def with_value_from_user(value) + type.assert_valid_value(value) + self.class.from_user(name, value, type, original_attribute || self) + end + + def with_value_from_database(value) + self.class.from_database(name, value, type) + end + + def with_cast_value(value) + self.class.with_cast_value(name, value, type) + end + + def with_type(type) + if changed_in_place? + with_value_from_user(value).with_type(type) + else + self.class.new(name, value_before_type_cast, type, original_attribute) + end + end + + def type_cast(*) + raise NotImplementedError + end + + def initialized? + true + end + + def came_from_user? + false + end + + def has_been_read? + defined?(@value) + end + + def ==(other) + self.class == other.class && + name == other.name && + value_before_type_cast == other.value_before_type_cast && + type == other.type + end + alias eql? == + + def hash + [self.class, name, value_before_type_cast, type].hash + end + + def init_with(coder) + @name = coder["name"] + @value_before_type_cast = coder["value_before_type_cast"] + @type = coder["type"] + @original_attribute = coder["original_attribute"] + @value = coder["value"] if coder.map.key?("value") + end + + def encode_with(coder) + coder["name"] = name + coder["value_before_type_cast"] = value_before_type_cast unless value_before_type_cast.nil? + coder["type"] = type if type + coder["original_attribute"] = original_attribute if original_attribute + coder["value"] = value if defined?(@value) + end + + protected + + attr_reader :original_attribute + alias_method :assigned?, :original_attribute + + def original_value_for_database + if assigned? + original_attribute.original_value_for_database + else + _original_value_for_database + end + end + + private + def initialize_dup(other) + if defined?(@value) && @value.duplicable? + @value = @value.dup + end + end + + def changed_from_assignment? + assigned? && type.changed?(original_value, value, value_before_type_cast) + end + + def _original_value_for_database + type.serialize(original_value) + end + + class FromDatabase < Attribute # :nodoc: + def type_cast(value) + type.deserialize(value) + end + + def _original_value_for_database + value_before_type_cast + end + end + + class FromUser < Attribute # :nodoc: + def type_cast(value) + type.cast(value) + end + + def came_from_user? + !type.value_constructed_by_mass_assignment?(value_before_type_cast) + end + end + + class WithCastValue < Attribute # :nodoc: + def type_cast(value) + value + end + + def changed_in_place? + false + end + end + + class Null < Attribute # :nodoc: + def initialize(name) + super(name, nil, Type.default_value) + end + + def type_cast(*) + nil + end + + def with_type(type) + self.class.with_cast_value(name, nil, type) + 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: + UNINITIALIZED_ORIGINAL_VALUE = Object.new + + def initialize(name, type) + super(name, nil, type) + end + + def value + if block_given? + yield name + end + end + + def original_value + UNINITIALIZED_ORIGINAL_VALUE + end + + def value_for_database + end + + def initialized? + false + end + + def with_type(type) + self.class.new(name, type) + end + end + + private_constant :FromDatabase, :FromUser, :Null, :Uninitialized, :WithCastValue + end +end |