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 ActiveModel::Serialization module, so there is no need to explicitly include ActiveModel::Serialization.
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 :only, :except, :methods and :include. The following are all valid examples:
person.serializable_hash(only: 'name')
person.serializable_hash(include: :address)
person.serializable_hash(include: { address: { only: 'city' }})
Methods
Instance Public methods
serializable_hash(options = nil)
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 :include 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"}]}
📝 Source code
# File activemodel/lib/active_model/serialization.rb, line 126
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