require "active_support/core_ext/class/attribute"
require "active_support/core_ext/module/anonymous"
require "set"
module ActiveModel
class OrderedSet
def initialize(array)
@array = array
@hash = {}
array.each do |item|
@hash[item] = true
end
end
def merge!(other)
other.each do |item|
next if @hash.key?(item)
@hash[item] = true
@array.push item
end
end
def to_a
@array
end
end
# Active Model Array Serializer
#
# It serializes an array checking if each element that implements
# the +active_model_serializer+ method.
class ArraySerializer
attr_reader :object, :options
def initialize(object, options={})
@object, @options = object, options
end
def serializable_array
@object.map do |item|
if item.respond_to?(:active_model_serializer) && (serializer = item.active_model_serializer)
serializer.new(item, @options)
else
item
end
end
end
def as_json(*args)
@options[:hash] = hash = {}
@options[:unique_values] = {}
array = serializable_array.map(&:serializable_hash)
if root = @options[:root]
hash.merge!(root => array)
else
array
end
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 options. For example,
# one may do in a controller:
#
# PostSerializer.new(@post, :scope => current_user).to_json
#
# The object to be serialized is the +@post+ and the current user is passed
# in for authorization purposes.
#
# 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 #:nodoc:
class_attribute :options
def self.refine(name, class_options)
current_class = self
Class.new(self) do
singleton_class.class_eval do
define_method(:to_s) do
"(subclass of #{current_class.name})"
end
alias inspect to_s
end
self.options = class_options
end
end
self.options = {}
def initialize(name, source, options={})
@name = name
@source = source
@options = options
end
def option(key, default=nil)
if @options.key?(key)
@options[key]
elsif self.class.options.key?(key)
self.class.options[key]
else
default
end
end
def target_serializer
option(:serializer)
end
def source_serializer
@source
end
def key
option(:key) || @name
end
def root
option(:root) || plural_key
end
def name
option(:name) || @name
end
def associated_object
option(:value) || source_serializer.send(name)
end
def embed_ids?
option(:embed, source_serializer._embed) == :ids
end
def embed_objects?
option(:embed, source_serializer._embed) == :objects
end
def embed_in_root?
option(:include, source_serializer._root_embed)
end
protected
def find_serializable(object)
if target_serializer
target_serializer.new(object, source_serializer.options)
elsif object.respond_to?(:active_model_serializer) && (ams = object.active_model_serializer)
ams.new(object, source_serializer.options)
else
object
end
end
end
class HasMany < Config #:nodoc:
alias plural_key key
def serialize
associated_object.map do |item|
find_serializable(item).serializable_hash
end
end
alias serialize_many serialize
def serialize_ids
# Use pluck or select_columns if available
# return collection.ids if collection.respond_to?(:ids)
associated_object.map do |item|
item.read_attribute_for_serialization(:id)
end
end
end
class HasOne < Config #:nodoc:
def plural_key
key.to_s.pluralize.to_sym
end
def serialize
object = associated_object
object && find_serializable(object).serializable_hash
end
def serialize_many
object = associated_object
value = object && find_serializable(object).serializable_hash
value ? [value] : []
end
def serialize_ids
if object = associated_object
object.read_attribute_for_serialization(:id)
else
nil
end
end
end
end
class_attribute :_attributes
self._attributes = {}
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 = _attributes.dup
attrs.each do |attr|
attribute attr
end
end
def attribute(attr, options={})
self._attributes = _attributes.merge(attr => options[:key] || attr)
unless method_defined?(attr)
class_eval "def #{attr}() object.read_attribute_for_serialization(:#{attr}) end", __FILE__, __LINE__
end
end
def associate(klass, attrs) #:nodoc:
options = attrs.extract_options!
self._associations = _associations.dup
attrs.each do |attr|
unless method_defined?(attr)
class_eval "def #{attr}() object.#{attr} end", __FILE__, __LINE__
end
self._associations[attr] = klass.refine(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
# Return a schema hash for the current serializer. This information
# can be used to generate clients for the serialized output.
#
# The schema hash has two keys: +attributes+ and +associations+.
#
# The +attributes+ hash looks like this:
#
# { :name => :string, :age => :integer }
#
# The +associations+ hash looks like this:
# { :posts => { :has_many => :posts } }
#
# If :key is used:
#
# class PostsSerializer < ActiveModel::Serializer
# has_many :posts, :key => :my_posts
# end
#
# the hash looks like this:
#
# { :my_posts => { :has_many => :posts }
#
# This information is extracted from the serializer's model class,
# which is provided by +SerializerClass.model_class+.
#
# The schema method uses the +columns_hash+ and +reflect_on_association+
# methods, provided by default by ActiveRecord. You can implement these
# methods on your custom models if you want the serializer's schema method
# to work.
#
# TODO: This is currently coupled to Active Record. We need to
# figure out a way to decouple those two.
def schema
klass = model_class
columns = klass.columns_hash
attrs = _attributes.inject({}) do |hash, (name,key)|
column = columns[name.to_s]
hash.merge key => column.type
end
associations = _associations.inject({}) do |hash, (attr,association_class)|
association = association_class.new(attr, self)
model_association = klass.reflect_on_association(association.name)
hash.merge association.key => { model_association.macro => model_association.name }
end
{ :attributes => attrs, :associations => associations }
end
# The model class associated with this serializer.
def model_class
name.sub(/Serializer$/, '').constantize
end
# Define how associations should be embedded.
#
# embed :objects # Embed associations as full objects
# embed :ids # Embed only the association ids
# embed :ids, :include => true # Embed the association ids and include objects in the root
#
def embed(type, options={})
self._embed = type
self._root_embed = true if options[:include]
end
# Defines the root used on serialization. If false, disables the root.
def root(name)
self._root = name
end
def inherited(klass) #:nodoc:
return if klass.anonymous?
name = klass.name.demodulize.underscore.sub(/_serializer$/, '')
klass.class_eval do
alias_method name.to_sym, :object
root name.to_sym unless self._root == false
end
end
end
attr_reader :object, :options
def initialize(object, options={})
@object, @options = object, options
end
def url_options
@options[:url_options]
end
# Returns a json representation of the serializable
# object including the root.
def as_json(options=nil)
options ||= {}
if root = options.fetch(:root, @options.fetch(:root, _root))
@options[:hash] = hash = {}
@options[:unique_values] = {}
hash.merge!(root => serializable_hash)
hash
else
serializable_hash
end
end
# Returns a hash representation of the serializable
# object without the root.
def serializable_hash
node = attributes
include_associations!(node) if _embed
node
end
def include_associations!(node)
_associations.each do |attr, klass|
opts = { :node => node }
if options.include?(:include) || options.include?(:exclude)
opts[:include] = included_association?(attr)
end
include! attr, opts
end
end
def included_association?(name)
if options.key?(:include)
options[:include].include?(name)
elsif options.key?(:exclude)
!options[:exclude].include?(name)
else
true
end
end
def include!(name, options={})
# Make sure that if a special options[:hash] was passed in, we generate
# a new unique values hash and don't clobber the original. If the hash
# passed in is the same as the current options hash, use the current
# unique values.
#
# TODO: Should passing in a Hash even be public API here?
unique_values =
if hash = options[:hash]
if @options[:hash] == hash
@options[:unique_values] ||= {}
else
{}
end
else
hash = @options[:hash]
@options[:unique_values] ||= {}
end
node = options[:node]
value = options[:value]
association_class =
if klass = _associations[name]
klass
elsif value.respond_to?(:to_ary)
Associations::HasMany
else
Associations::HasOne
end
association = association_class.new(name, self, options)
if association.embed_ids?
node[association.key] = association.serialize_ids
if association.embed_in_root?
merge_association hash, association.root, association.serialize_many, unique_values
end
elsif association.embed_objects?
node[association.key] = association.serialize
end
end
# In some cases, an Array of associations is built by merging the associated
# content for all of the children. For instance, if a Post has_many comments,
# which has_many tags, the top-level :tags key will contain the merged list
# of all tags for all comments of the post.
#
# In order to make this efficient, we store a :unique_values hash containing
# a unique list of all of the objects that are already in the Array. This
# avoids the need to scan through the Array looking for entries every time
# we want to merge a new list of values.
def merge_association(hash, key, value, unique_values)
if current_value = unique_values[key]
current_value.merge! value
hash[key] = current_value.to_a
elsif value
hash[key] = value
unique_values[key] = OrderedSet.new(value)
end
end
# Returns a hash representation of the serializable
# object attributes.
def attributes
hash = {}
_attributes.each do |name,key|
hash[key] = read_attribute_for_serialization(name)
end
hash
end
alias :read_attribute_for_serialization :send
end
end
class Array
# Array uses ActiveModel::ArraySerializer.
def active_model_serializer
ActiveModel::ArraySerializer
end
end