Module: Dynabix::Metadata

Defined in:
lib/dynabix/metadata.rb

Overview

Extending ActiveRecord with dynamic accessors for serialization

Instance Method Summary collapse

Instance Method Details

#has_metadata(serializer = :metadata, *attributes) ⇒ void

This method returns an undefined value.

Set up the model for serialization to a HashWithIndifferentAccess.

Examples:

Using the default column name “:metadata”, specify the attributes in a separate step


class Thing < ActiveRecord::Base
  has_metadata

  # full accessors
  metadata_accessor :breakfast_food, :wheat_products, :needs_milk

  # read-only
  metadata_reader :friends_with_spoons
end

Specifying attributes for full attributes accessors in one step


class Thing < ActiveRecord::Base
  has_metadata :metadata, :breakfast_food, :wheat_products, :needs_milk
end

Specifying multiple metadata serializers (Ruby 1.9 only)


class Thing < ActiveRecord::Base
  has_metadata :cows
  has_metadata :chickens, :tasty, :feather_count

  # read-only
  cow_reader :likes_milk, :hates_eggs

  # write-only
  cow_writer :no_wheat_products

  # extra full accessors for chickens
  chicken_accessor :color, :likes_eggs
end

Parameters:

  • serializer, (Symbol) —

    the symbolized name (:metadata) of the database text column used for serialization

  • optional (Array<Symbol>) —

    list of attribute names to add to the model as full accessors



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# File 'lib/dynabix/metadata.rb', line 49

def has_metadata(serializer=:metadata, *attributes)
  serialize(serializer, HashWithIndifferentAccess)

  if RUBY_VERSION < '1.9'
    raise "has_metadata serializer must be named ':metadata', this restriction is lifted in Ruby 1.9+" unless serializer == :metadata
  else
    # we can safely define additional accessors, Ruby 1.8 will only
    # be able to use the statically defined :metadata_accessor
    if serializer != :metadata

      # define the class accessor
      define_singleton_method "#{serializer}_accessor" do |*attrs|
        attrs.each do |attr|
          create_reader(serializer, attr)
          create_writer(serializer, attr)
        end
      end

      # define the class read accessor
      define_singleton_method "#{serializer}_reader" do |*attrs|
        attrs.each do |attr|
          create_reader(serializer, attr)
        end
      end

      # define the class write accessor
      define_singleton_method "#{serializer}_writer" do |*attrs|
        attrs.each do |attr|
          create_writer(serializer, attr)
        end
      end

    end
  end

  # Define each of the attributes for this serializer
  attributes.each do |attr|
    create_reader(serializer, attr)
    create_writer(serializer, attr)
  end
end

#metadata_accessor(*attrs) ⇒ void

This method returns an undefined value.

Default read/write accessor, user defined accessors are available under Ruby 1.9+

Parameters:

  • attributes (Array<Symbol>) 


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# File 'lib/dynabix/metadata.rb', line 96

def metadata_accessor(*attrs)
  attrs.each do |attr|
    create_reader(:metadata, attr)
    create_writer(:metadata, attr)
  end
end

#metadata_reader(*attrs) ⇒ void

This method returns an undefined value.

Default read accessor (getter), user defined accessors are available under Ruby 1.9+

Parameters:

  • attributes (Array<Symbol>) 


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# File 'lib/dynabix/metadata.rb', line 108

def metadata_reader(*attrs)
  attrs.each do |attr|
    create_reader(:metadata, attr)
  end
end

#metadata_writer(*attrs) ⇒ void

This method returns an undefined value.

Default write accessor (setter), user defined accessors are available under Ruby 1.9+

Parameters:

  • attributes (Array<Symbol>) 


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# File 'lib/dynabix/metadata.rb', line 119

def metadata_writer(*attrs)
  attrs.each do |attr|
    create_writer(:metadata, attr)
  end
end