ActiveRecord::Store with default values

Question

Using the new ActiveRecord::Store for serialization, the docs give the following example implementation:

class User < ActiveRecord::Base
  store :settings, accessors: [ :color, :homepage ]
end

Is it possible to declare attributes with default values, something akin to:

store :settings, accessors: { color: 'blue', homepage: 'rubyonrails.org' }

?

Answer 1

No, there's no way to supply defaults inside the store call. The store macro is quite simple:

def store(store_attribute, options = {})
  serialize store_attribute, Hash
  store_accessor(store_attribute, options[:accessors]) if options.has_key? :accessors
end

And all store_accessor does is iterate through the :accessors and create accessor and mutator methods for each one. If you try to use a Hash with :accessors you'll end up adding some things to your store that you didn't mean to.

If you want to supply defaults then you could use an after_initialize hook:

class User < ActiveRecord::Base
  store :settings, accessors: [ :color, :homepage ]
  after_initialize :initialize_defaults, :if => :new_record?
private
  def initialize_defaults
    self.color    = 'blue'            unless(color_changed?)
    self.homepage = 'rubyonrails.org' unless(homepage_changed?)
  end
end

Answer 2

I wanted to solve this too and ended up contributing to Storext:

class Book < ActiveRecord::Base
  include Storext.model

  # You can define attributes on the :data hstore column like this:
  store_attributes :data do
    author String
    title String, default: "Great Voyage"
    available Boolean, default: true
    copies Integer, default: 0
  end
end