diff options
Diffstat (limited to 'activemodel/lib/active_model/serialization.rb')
| -rw-r--r-- | activemodel/lib/active_model/serialization.rb | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/activemodel/lib/active_model/serialization.rb b/activemodel/lib/active_model/serialization.rb new file mode 100644 index 0000000000..47cb81bee5 --- /dev/null +++ b/activemodel/lib/active_model/serialization.rb @@ -0,0 +1,192 @@ +# frozen_string_literal: true + +require "active_support/core_ext/hash/except" +require "active_support/core_ext/hash/slice" + +module ActiveModel + # == Active \Model \Serialization + # + # Provides a basic serialization to a serializable_hash for your objects. + # + # A minimal implementation could be: + # + # class Person + # include ActiveModel::Serialization + # + # attr_accessor :name + # + # def attributes + # {'name' => nil} + # end + # end + # + # Which would provide you with: + # + # person = Person.new + # person.serializable_hash # => {"name"=>nil} + # person.name = "Bob" + # person.serializable_hash # => {"name"=>"Bob"} + # + # An +attributes+ hash must be defined and should contain any attributes you + # need to be serialized. Attributes must be strings, not symbols. + # When called, serializable hash will use instance methods that match the name + # of the attributes hash's keys. In order to override this behavior, take a look + # at the private method +read_attribute_for_serialization+. + # + # ActiveModel::Serializers::JSON module automatically includes + # the <tt>ActiveModel::Serialization</tt> module, so there is no need to + # explicitly include <tt>ActiveModel::Serialization</tt>. + # + # A minimal implementation including JSON would be: + # + # class Person + # include ActiveModel::Serializers::JSON + # + # attr_accessor :name + # + # def attributes + # {'name' => nil} + # end + # end + # + # Which would provide you with: + # + # person = Person.new + # person.serializable_hash # => {"name"=>nil} + # person.as_json # => {"name"=>nil} + # person.to_json # => "{\"name\":null}" + # + # person.name = "Bob" + # person.serializable_hash # => {"name"=>"Bob"} + # person.as_json # => {"name"=>"Bob"} + # person.to_json # => "{\"name\":\"Bob\"}" + # + # Valid options are <tt>:only</tt>, <tt>:except</tt>, <tt>:methods</tt> and + # <tt>:include</tt>. The following are all valid examples: + # + # person.serializable_hash(only: 'name') + # person.serializable_hash(include: :address) + # person.serializable_hash(include: { address: { only: 'city' }}) + module Serialization + # Returns a serialized hash of your object. + # + # class Person + # include ActiveModel::Serialization + # + # attr_accessor :name, :age + # + # def attributes + # {'name' => nil, 'age' => nil} + # end + # + # def capitalized_name + # name.capitalize + # end + # end + # + # person = Person.new + # person.name = 'bob' + # person.age = 22 + # person.serializable_hash # => {"name"=>"bob", "age"=>22} + # person.serializable_hash(only: :name) # => {"name"=>"bob"} + # person.serializable_hash(except: :name) # => {"age"=>22} + # person.serializable_hash(methods: :capitalized_name) + # # => {"name"=>"bob", "age"=>22, "capitalized_name"=>"Bob"} + # + # Example with <tt>:include</tt> option + # + # class User + # include ActiveModel::Serializers::JSON + # attr_accessor :name, :notes # Emulate has_many :notes + # def attributes + # {'name' => nil} + # end + # end + # + # class Note + # include ActiveModel::Serializers::JSON + # attr_accessor :title, :text + # def attributes + # {'title' => nil, 'text' => nil} + # end + # end + # + # note = Note.new + # note.title = 'Battle of Austerlitz' + # note.text = 'Some text here' + # + # user = User.new + # user.name = 'Napoleon' + # user.notes = [note] + # + # user.serializable_hash + # # => {"name" => "Napoleon"} + # user.serializable_hash(include: { notes: { only: 'title' }}) + # # => {"name" => "Napoleon", "notes" => [{"title"=>"Battle of Austerlitz"}]} + def serializable_hash(options = nil) + options ||= {} + + attribute_names = attributes.keys + if only = options[:only] + attribute_names &= Array(only).map(&:to_s) + elsif except = options[:except] + attribute_names -= Array(except).map(&:to_s) + end + + hash = {} + attribute_names.each { |n| hash[n] = read_attribute_for_serialization(n) } + + Array(options[:methods]).each { |m| hash[m.to_s] = send(m) } + + serializable_add_includes(options) do |association, records, opts| + hash[association.to_s] = if records.respond_to?(:to_ary) + records.to_ary.map { |a| a.serializable_hash(opts) } + else + records.serializable_hash(opts) + end + end + + hash + end + + private + + # Hook method defining how an attribute value should be retrieved for + # serialization. By default this is assumed to be an instance named after + # the attribute. Override this method in subclasses should you need to + # retrieve the value for a given attribute differently: + # + # class MyClass + # include ActiveModel::Serialization + # + # def initialize(data = {}) + # @data = data + # end + # + # def read_attribute_for_serialization(key) + # @data[key] + # end + # end + alias :read_attribute_for_serialization :send + + # Add associations specified via the <tt>:include</tt> option. + # + # Expects a block that takes as arguments: + # +association+ - name of the association + # +records+ - the association record(s) to be serialized + # +opts+ - options for the association records + def serializable_add_includes(options = {}) #:nodoc: + return unless includes = options[:include] + + unless includes.is_a?(Hash) + includes = Hash[Array(includes).map { |n| n.is_a?(Hash) ? n.to_a.first : [n, {}] }] + end + + includes.each do |association, opts| + if records = send(association) + yield association, records, opts + end + end + end + end +end |