Module: ActiveRecord::Serialization

Defined in:
lib/active_record/serialization.rb,
lib/active_record/serializers/xml_serializer.rb,
lib/active_record/serializers/json_serializer.rb

Defined Under Namespace

Classes: JsonSerializer, Serializer

Instance Method Summary collapse

Instance Method Details

#from_json(json) ⇒ Object 



60
61
62
63
 
# File 'lib/active_record/serializers/json_serializer.rb', line 60

def from_json(json)
  self.attributes = ActiveSupport::JSON.decode(json)
  self
end

#from_xml(xml) ⇒ Object 



128
129
130
131
 
# File 'lib/active_record/serializers/xml_serializer.rb', line 128

def from_xml(xml)
  self.attributes = Hash.from_xml(xml).values.first
  self
end

#to_json(options = {}) ⇒ Object

Returns a JSON string representing the model. Some configuration is available through options.

Without any options, the returned JSON string will include all the model’s attributes. For example:

konata = User.find(1)
konata.to_json

{"id": 1, "name": "Konata Izumi", "age": 16,
 "created_at": "2006/08/01", "awesome": true}

The :only and :except options can be used to limit the attributes included, and work similar to the #attributes method. For example:

konata.to_json(:only => [ :id, :name ])

{"id": 1, "name": "Konata Izumi"}

konata.to_json(:except => [ :id, :created_at, :age ])

{"name": "Konata Izumi", "awesome": true}

To include any methods on the model, use :methods.

konata.to_json(:methods => :permalink)

{"id": 1, "name": "Konata Izumi", "age": 16,
 "created_at": "2006/08/01", "awesome": true,
 "permalink": "1-konata-izumi"}

To include associations, use :include.

konata.to_json(:include => :posts)

{"id": 1, "name": "Konata Izumi", "age": 16,
 "created_at": "2006/08/01", "awesome": true,
 "posts": [{"id": 1, "author_id": 1, "title": "Welcome to the weblog"},
           {"id": 2, author_id: 1, "title": "So I was thinking"}]}

2nd level and higher order associations work as well:

konata.to_json(:include => { :posts => {
                               :include => { :comments => {
                                             :only => :body } },
                               :only => :title } })

{"id": 1, "name": "Konata Izumi", "age": 16,
 "created_at": "2006/08/01", "awesome": true,
 "posts": [{"comments": [{"body": "1st post!"}, {"body": "Second!"}],
            "title": "Welcome to the weblog"},
           {"comments": [{"body": "Don't think too hard"}],
            "title": "So I was thinking"}]}



56
57
58
 
# File 'lib/active_record/serializers/json_serializer.rb', line 56

def to_json(options = {})
  JsonSerializer.new(self, options).to_s
end

#to_xml(options = {}, &block) ⇒ Object

Builds an XML document to represent the model. Some configuration is available through options, however more complicated cases should override ActiveRecord’s to_xml.

By default the generated XML document will include the processing instruction and all object’s attributes. For example:

<?xml version="1.0" encoding="UTF-8"?>
<topic>
  <title>The First Topic</title>
  <author-name>David</author-name>
  <id type="integer">1</id>
  <approved type="boolean">false</approved>
  <replies-count type="integer">0</replies-count>
  <bonus-time type="datetime">2000-01-01T08:28:00+12:00</bonus-time>
  <written-on type="datetime">2003-07-16T09:28:00+1200</written-on>
  <content>Have a nice day</content>
  <author-email-address>[email protected]</author-email-address>
  <parent-id></parent-id>
  <last-read type="date">2004-04-15</last-read>
</topic>

This behavior can be controlled with :only, :except, :skip_instruct, :skip_types and :dasherize. The :only and :except options are the same as for the #attributes method. The default is to dasherize all column names, to disable this, set :dasherize to false. To not have the column type included in the XML output, set :skip_types to true.

For instance:

topic.to_xml(:skip_instruct => true, :except => [ :id, :bonus_time, :written_on, :replies_count ])

<topic>
  <title>The First Topic</title>
  <author-name>David</author-name>
  <approved type="boolean">false</approved>
  <content>Have a nice day</content>
  <author-email-address>[email protected]</author-email-address>
  <parent-id></parent-id>
  <last-read type="date">2004-04-15</last-read>
</topic>

To include first level associations use :include

firm.to_xml :include => [ :account, :clients ]

<?xml version="1.0" encoding="UTF-8"?>
<firm>
  <id type="integer">1</id>
  <rating type="integer">1</rating>
  <name>37signals</name>
  <clients type="array">
    <client>
      <rating type="integer">1</rating>
      <name>Summit</name>
    </client>
    <client>
      <rating type="integer">1</rating>
      <name>Microsoft</name>
    </client>
  </clients>
  <account>
    <id type="integer">1</id>
    <credit-limit type="integer">50</credit-limit>
  </account>
</firm>

To include any methods on the object(s) being called use :methods

firm.to_xml :methods => [ :calculated_earnings, :real_earnings ]

<firm>
  # ... normal attributes as shown above ...
  <calculated-earnings>100000000000000000</calculated-earnings>
  <real-earnings>5</real-earnings>
</firm>

To call any Proc’s on the object(s) use :procs. The Proc’s are passed a modified version of the options hash that was given to #to_xml.

proc = Proc.new { |options| options[:builder].tag!('abc', 'def') }
firm.to_xml :procs => [ proc ]

<firm>
  # ... normal attributes as shown above ...
  <abc>def</abc>
</firm>

Alternatively, you can also just yield the builder object as part of the to_xml call:

firm.to_xml do |xml|
  xml.creator do
    xml.first_name "David"
    xml.last_name "Heinemeier Hansson"
  end
end

<firm>
  # ... normal attributes as shown above ...
  <creator>
    <first_name>David</first_name>
    <last_name>Heinemeier Hansson</last_name>
  </creator>
</firm>

You can override the to_xml method in your ActiveRecord::Base subclasses if you need to. The general form of doing this is

class IHaveMyOwnXML < ActiveRecord::Base
  def to_xml(options = {})
    options[:indent] ||= 2
    xml = options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent])
    xml.instruct! unless options[:skip_instruct]
    xml.level_one do
      xml.tag!(:second_level, 'content')
    end
  end
end



123
124
125
126
 
# File 'lib/active_record/serializers/xml_serializer.rb', line 123

def to_xml(options = {}, &block)
  serializer = XmlSerializer.new(self, options)
  block_given? ? serializer.to_s(&block) : serializer.to_s
end