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# frozen_string_literal: true
# ActiveModelSerializers::Model is a convenient superclass for making your models
# from Plain-Old Ruby Objects (PORO). It also serves as a reference implementation
# that satisfies ActiveModel::Serializer::Lint::Tests.
require 'active_support/core_ext/hash'
module ActiveModelSerializers
class Model
include ActiveModel::Serializers::JSON
include ActiveModel::Model
# Declare names of attributes to be included in +attributes+ hash.
# Is only available as a class-method since the ActiveModel::Serialization mixin in Rails
# uses an +attribute_names+ local variable, which may conflict if we were to add instance methods here.
#
# @overload attribute_names
# @return [Array<Symbol>]
class_attribute :attribute_names, instance_writer: false, instance_reader: false
# Initialize +attribute_names+ for all subclasses. The array is usually
# mutated in the +attributes+ method, but can be set directly, as well.
self.attribute_names = []
# Easily declare instance attributes with setters and getters for each.
#
# To initialize an instance, all attributes must have setters.
# However, the hash returned by +attributes+ instance method will ALWAYS
# be the value of the initial attributes, regardless of what accessors are defined.
# The only way to change the change the attributes after initialization is
# to mutate the +attributes+ directly.
# Accessor methods do NOT mutate the attributes. (This is a bug).
#
# @note For now, the Model only supports the notion of 'attributes'.
# In the tests, there is a special Model that also supports 'associations'. This is
# important so that we can add accessors for values that should not appear in the
# attributes hash when modeling associations. It is not yet clear if it
# makes sense for a PORO to have associations outside of the tests.
#
# @overload attributes(names)
# @param names [Array<String, Symbol>]
# @param name [String, Symbol]
def self.attributes(*names)
self.attribute_names |= names.map(&:to_sym)
# Silence redefinition of methods warnings
ActiveModelSerializers.silence_warnings do
attr_accessor(*names)
end
end
# Opt-in to breaking change
def self.derive_attributes_from_names_and_fix_accessors
unless included_modules.include?(DeriveAttributesFromNamesAndFixAccessors)
prepend(DeriveAttributesFromNamesAndFixAccessors)
end
end
module DeriveAttributesFromNamesAndFixAccessors
def self.included(base)
# NOTE that +id+ will always be in +attributes+.
base.attributes :id
end
# Override the +attributes+ method so that the hash is derived from +attribute_names+.
#
# The fields in +attribute_names+ determines the returned hash.
# +attributes+ are returned frozen to prevent any expectations that mutation affects
# the actual values in the model.
def attributes
self.class.attribute_names.each_with_object({}) do |attribute_name, result|
result[attribute_name] = public_send(attribute_name).freeze
end.with_indifferent_access.freeze
end
end
# Support for validation and other ActiveModel::Errors
# @return [ActiveModel::Errors]
attr_reader :errors
# (see #updated_at)
attr_writer :updated_at
# The only way to change the attributes of an instance is to directly mutate the attributes.
# @example
#
# model.attributes[:foo] = :bar
# @return [Hash]
attr_reader :attributes
# @param attributes [Hash]
def initialize(attributes = {})
attributes ||= {} # protect against nil
@attributes = attributes.symbolize_keys.with_indifferent_access
@errors = ActiveModel::Errors.new(self)
super
end
# Defaults to the downcased model name.
# This probably isn't a good default, since it's not a unique instance identifier,
# but that's what is currently implemented \_('-')_/.
#
# @note Though +id+ is defined, it will only show up
# in +attributes+ when it is passed in to the initializer or added to +attributes+,
# such as <tt>attributes[:id] = 5</tt>.
# @return [String, Numeric, Symbol]
def id
attributes.fetch(:id) do
defined?(@id) ? @id : self.class.model_name.name && self.class.model_name.name.downcase
end
end
# When not set, defaults to the time the file was modified.
#
# @note Though +updated_at+ and +updated_at=+ are defined, it will only show up
# in +attributes+ when it is passed in to the initializer or added to +attributes+,
# such as <tt>attributes[:updated_at] = Time.current</tt>.
# @return [String, Numeric, Time]
def updated_at
attributes.fetch(:updated_at) do
defined?(@updated_at) ? @updated_at : File.mtime(__FILE__)
end
end
# To customize model behavior, this method must be redefined. However,
# there are other ways of setting the +cache_key+ a serializer uses.
# @return [String]
def cache_key
ActiveSupport::Cache.expand_cache_key([
self.class.model_name.name.downcase,
"#{id}-#{updated_at.strftime('%Y%m%d%H%M%S%9N')}"
].compact)
end
end
end
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