require "active_support/core_ext/class/attribute"
require "active_support/core_ext/string/inflections"
require "active_support/core_ext/module/anonymous"
require "set"
module ActiveModel
# Active Model Array Serializer
#
# It serializes an array checking if each element that implements
# the +active_model_serializer+ method passing down the current scope.
class ArraySerializer
attr_reader :object, :scope
def initialize(object, scope)
@object, @scope = object, scope
end
def serializable_array
@object.map do |item|
if item.respond_to?(:active_model_serializer) && (serializer = item.active_model_serializer)
serializer.new(item, scope)
else
item
end
end
end
def as_json(*args)
serializable_array.as_json(*args)
end
end
# Active Model Serializer
#
# Provides a basic serializer implementation that allows you to easily
# control how a given object is going to be serialized. On initialization,
# it expects to object as arguments, a resource and a scope. For example,
# one may do in a controller:
#
# PostSerializer.new(@post, current_user).to_json
#
# The object to be serialized is the +@post+ and the scope is +current_user+.
#
# We use the scope to check if a given attribute should be serialized or not.
# For example, some attributes maybe only be returned if +current_user+ is the
# author of the post:
#
# class PostSerializer < ActiveModel::Serializer
# attributes :title, :body
# has_many :comments
#
# private
#
# def attributes
# hash = super
# hash.merge!(:email => post.email) if author?
# hash
# end
#
# def author?
# post.author == scope
# end
# end
#
class Serializer
module Associations #:nodoc:
class Config < Struct.new(:name, :options) #:nodoc:
def serializer
options[:serializer]
end
end
class HasMany < Config #:nodoc:
def serialize(collection, scope)
collection.map do |item|
serializer.new(item, scope).serializable_hash
end
end
def serialize_ids(collection, scope)
# use named scopes if they are present
# return collection.ids if collection.respond_to?(:ids)
collection.map do |item|
item.read_attribute_for_serialization(:id)
end
end
end
class HasOne < Config #:nodoc:
def serialize(object, scope)
object && serializer.new(object, scope).serializable_hash
end
def serialize_ids(object, scope)
object && object.read_attribute_for_serialization(:id)
end
end
end
class_attribute :_attributes
self._attributes = Set.new
class_attribute :_associations
self._associations = []
class_attribute :_root
class_attribute :_embed
self._embed = :objects
class_attribute :_root_embed
class << self
# Define attributes to be used in the serialization.
def attributes(*attrs)
self._attributes += attrs
end
def associate(klass, attrs) #:nodoc:
options = attrs.extract_options!
self._associations += attrs.map do |attr|
unless method_defined?(attr)
class_eval "def #{attr}() object.#{attr} end", __FILE__, __LINE__
end
options[:serializer] ||= const_get("#{attr.to_s.camelize}Serializer")
klass.new(attr, options)
end
end
# Defines an association in the object should be rendered.
#
# The serializer object should implement the association name
# as a method which should return an array when invoked. If a method
# with the association name does not exist, the association name is
# dispatched to the serialized object.
def has_many(*attrs)
associate(Associations::HasMany, attrs)
end
# Defines an association in the object should be rendered.
#
# The serializer object should implement the association name
# as a method which should return an object when invoked. If a method
# with the association name does not exist, the association name is
# dispatched to the serialized object.
def has_one(*attrs)
associate(Associations::HasOne, attrs)
end
# Define how associations should be embedded.
#
# embed :objects # Embed associations as full objects
# embed :ids # Embed only the association ids
# embed :ids, :include => true # Embed the association ids and include objects in the root
#
def embed(type, options={})
self._embed = type
self._root_embed = true if options[:include]
end
# Defines the root used on serialization. If false, disables the root.
def root(name)
self._root = name
end
def inherited(klass) #:nodoc:
return if klass.anonymous?
name = klass.name.demodulize.underscore.sub(/_serializer$/, '')
klass.class_eval do
alias_method name.to_sym, :object
root name.to_sym unless self._root == false
end
end
end
attr_reader :object, :scope
def initialize(object, scope)
@object, @scope = object, scope
end
# Returns a json representation of the serializable
# object including the root.
def as_json(*)
if _root
hash = { _root => serializable_hash }
hash.merge!(associations) if _root_embed
hash
else
serializable_hash
end
end
# Returns a hash representation of the serializable
# object without the root.
def serializable_hash
if _embed == :ids
attributes.merge(association_ids)
elsif _embed == :objects
attributes.merge(associations)
else
attributes
end
end
# Returns a hash representation of the serializable
# object associations.
def associations
hash = {}
_associations.each do |association|
associated_object = send(association.name)
hash[association.name] = association.serialize(associated_object, scope)
end
hash
end
# Returns a hash representation of the serializable
# object associations ids.
def association_ids
hash = {}
_associations.each do |association|
associated_object = send(association.name)
hash[association.name] = association.serialize_ids(associated_object, scope)
end
hash
end
# Returns a hash representation of the serializable
# object attributes.
def attributes
hash = {}
_attributes.each do |name|
hash[name] = @object.read_attribute_for_serialization(name)
end
hash
end
end
end
class Array
# Array uses ActiveModel::ArraySerializer.
def active_model_serializer
ActiveModel::ArraySerializer
end
end
