ActiveRecord::Store with default values - ruby-on-rails

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

Answer 3

try to use https://github.com/byroot/activerecord-typedstore gem. It allows you to set default value, use validation end other.

Answer 4

The following code has advantage of the defaults not being saved on every user record which reduces database storage usage and makes it easy in case if you want to change the defaults
class User < ApplicationRecord
DEFAULT_SETTINGS = { color: 'blue', homepage: 'rubyonrails.org' }
store :settings, accessors: DEFAULT_SETTINGS.keys
DEFAULT_SETTINGS.each do |key,value|
define_method(key) {
settings[key] or value
}
end
end

Answer 5

Here's what I just hacked together to solve this problem:
# migration
def change
add_column :my_objects, :settings, :text
end
# app/models/concerns/settings_accessors_with_defaults.rb
module SettingsAccessorsWithDefaults
extend ActiveSupport::Concern
included do
serialize :settings, Hash
cattr_reader :default_settings
end
def settings
self.class.default_settings.merge(self[:settings])
end
def restore_setting_to_default(key)
self[:settings].delete key
end
module ClassMethods
def load_default_settings(accessors_and_values)
self.class_variable_set '##default_settings', accessors_and_values
self.default_settings.keys.each do |key|
define_method("#{key}=") do |value|
self[:settings][key.to_sym] = value
end
define_method(key) do
self.settings[key.to_sym]
end
end
end
end
end
# app/models/my_object.rb
include SettingsAccessorsWithDefaults
load_default_settings(
attribute_1: 'default_value',
attribute_2: 'default_value_2'
)
validates :attribute_1, presence: true
irb(main):004:0> MyObject.default_settings
=> {:attribute_1=>'default_value', :attribute_2=>'default_value_2'}
irb(main):005:0> m = MyObject.last
=> #<MyObject ..., settings: {}>
irb(main):005:0> m.settings
=> {:attribute_1=>'default_value', :attribute_2=>'default_value_2'}
irb(main):007:0> m.attribute_1 = 'foo'
=> "foo"
irb(main):008:0> m.settings
=> {:attribute_1=>"foo", :attribute_2=>'default_value_2'}
irb(main):009:0> m
=> #<MyObject ..., settings: {:attribute_1=>"foo"}>