module ActiveRecord::Serialization - activerecord-4.2.3 Documentation

# module ActiveRecord::Serialization

# Active Record Serialization¶ ↑

### Public Instance Methods

serializable_hash(options = nil) click to toggle source
Calls superclass method

    # File lib/active_record/serialization.rb, line 11
    def serializable_hash(options = nil)
      options = options.try(:clone) || {}

      options[:except] = Array(options[:except]).map { |n| n.to_s }
      options[:except] |= Array(self.class.inheritance_column)

      super(options)
    end

to_xml(options = {}, &block) click to toggle source

Builds an XML document to represent the model. Some configuration is available through `options`. However more complicated cases should override ActiveRecord::Base#to_xml.

By default the generated XML document will include the processing instruction and all the 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`, `:dasherize` and `:camelize` . The `:only` and `:except` options are the same as for the `attributes` method. The default is to dasherize all column names, but you can disable this setting `:dasherize` to `false`. Setting `:camelize` to `true` will camelize all column names - this also overrides `:dasherize`. 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>

Additionally, the record being serialized will be passed to a Proc's second parameter. This allows for ad hoc additions to the resultant document that incorporate the context of the record being serialized. And by leveraging the closure created by a Proc, #to_xml can be used to add elements that normally fall outside of the scope of the model – for example, generating and appending URLs associated with models.

    proc = Proc.new { |options, record| options[:builder].tag!('name-reverse', record.name.reverse) }
    firm.to_xml procs: [ proc ]

    <firm>
      # ... normal attributes as shown above ...
      <name-reverse>slangis73</name-reverse>
    </firm>

To include deeper levels of associations pass a hash like this:

    firm.to_xml include: {account: {}, clients: {include: :address}}
    <?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>
          <address>
            ...
          </address>
        </client>
        <client>
          <rating type="integer">1</rating>
          <name>Microsoft</name>
          <address>
            ...
          </address>
        </client>
      </clients>
      <account>
        <id type="integer">1</id>
        <credit-limit type="integer">50</credit-limit>
      </account>
    </firm>

To include any methods on the model 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 additional Procs use `:procs`. The Procs 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 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>

As noted above, you may override `to_xml` in your ActiveRecord::Base subclasses to have complete control about what's generated. The general form of doing this is:

    class IHaveMyOwnXML < ActiveRecord::Base
      def to_xml(options = {})
        require 'builder'
        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

    # File lib/active_record/serializers/xml_serializer.rb, line 174
    def to_xml(options = {}, &block)
      XmlSerializer.new(self, options).serialize(&block)
    end