Module | ActiveRecord::Serialization
In: | lib/active_record/serialization.rb lib/active_record/serializers/json_serializer.rb lib/active_record/serializers/xml_serializer.rb

### Methods

from_json from_xml to_json to_xml

### Public Instance methods

from_json(json)
from_xml(xml)
to_json(options = {})

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"}]}

to_xml(options = {}, &block)

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>david@loudthinking.com</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>david@loudthinking.com</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

[Validate]