跳至内容 跳至搜索

Active Model 序列化

为您的对象提供基本的序列化到 serializable_hash。

一个最小的实现可能是

class Person
  include ActiveModel::Serialization

  attr_accessor :name

  def attributes
    {'name' => nil}
  end
end

这将为您提供

person = Person.new
person.serializable_hash   # => {"name"=>nil}
person.name = "Bob"
person.serializable_hash   # => {"name"=>"Bob"}

必须定义一个 attributes 哈希，它应该包含您需要序列化的任何属性。 Attributes 必须是字符串，而不是符号。调用时，可序列化哈希将使用与属性哈希键名称匹配的实例方法。为了覆盖此行为，请覆盖 read_attribute_for_serialization 方法。

ActiveModel::Serializers::JSON 模块自动包含 ActiveModel::Serialization 模块，因此无需显式包含 ActiveModel::Serialization。

一个包含 JSON 的最小实现将是

class Person
  include ActiveModel::Serializers::JSON

  attr_accessor :name

  def attributes
    {'name' => nil}
  end
end

这将为您提供

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\"}"

有效的选项是 :only、:except、:methods 和 :include。以下是所有有效的示例

person.serializable_hash(only: 'name')
person.serializable_hash(include: :address)
person.serializable_hash(include: { address: { only: 'city' }})
方法
S

实例公共方法

serializable_hash(options = nil)

返回对象的序列化哈希。

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"}

使用 :include 选项的示例

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"}]}

来源：显示 | 在 GitHub 上

# File activemodel/lib/active_model/serialization.rb, line 125
def serializable_hash(options = nil)
  attribute_names = attribute_names_for_serialization

  return serializable_attributes(attribute_names) if options.blank?

  if only = options[:only]
    attribute_names = Array(only).map(&:to_s) & attribute_names
  elsif except = options[:except]
    attribute_names -= Array(except).map(&:to_s)
  end

  hash = serializable_attributes(attribute_names)

  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