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require 'active_support/core_ext/hash/indifferent_access'
module ActiveRecord
# Store gives you a thin wrapper around serialize for the purpose of storing hashes in a single column.
# It's like a simple key/value store backed into your record when you don't care about being able to
# query that store outside the context of a single record.
#
# You can then declare accessors to this store that are then accessible just like any other attribute
# of the model. This is very helpful for easily exposing store keys to a form or elsewhere that's
# already built around just accessing attributes on the model.
#
# Make sure that you declare the database column used for the serialized store as a text, so there's
# plenty of room.
#
# You can set custom coder to encode/decode your serialized attributes to/from different formats.
# JSON, YAML, Marshal are supported out of the box. Generally it can be any wrapper that provides +load+ and +dump+.
#
# Examples:
#
# class User < ActiveRecord::Base
# store :settings, accessors: [ :color, :homepage ], coder: JSON
# end
#
# u = User.new(color: 'black', homepage: '37signals.com')
# u.color # Accessor stored attribute
# u.settings[:country] = 'Denmark' # Any attribute, even if not specified with an accessor
#
# # There is no difference between strings and symbols for accessing custom attributes
# u.settings[:country] # => 'Denmark'
# u.settings['country'] # => 'Denmark'
#
# # Add additional accessors to an existing store through store_accessor
# class SuperUser < User
# store_accessor :settings, :privileges, :servants
# end
module Store
extend ActiveSupport::Concern
module ClassMethods
def store(store_attribute, options = {})
serialize store_attribute, options.fetch(:coder, ActiveSupport::HashWithIndifferentAccess)
store_accessor(store_attribute, options[:accessors]) if options.has_key? :accessors
end
def store_accessor(store_attribute, *keys)
keys.flatten.each do |key|
define_method("#{key}=") do |value|
initialize_store_attribute(store_attribute)
send(store_attribute)[key] = value
send("#{store_attribute}_will_change!")
end
define_method(key) do
initialize_store_attribute(store_attribute)
send(store_attribute)[key]
end
end
end
end
private
def initialize_store_attribute(store_attribute)
case attribute = send(store_attribute)
when ActiveSupport::HashWithIndifferentAccess
# Already initialized. Do nothing.
when Hash
# Initialized as a Hash. Convert to indifferent access.
send :"#{store_attribute}=", attribute.with_indifferent_access
else
# Uninitialized. Set to an indifferent hash.
send :"#{store_attribute}=", ActiveSupport::HashWithIndifferentAccess.new
end
end
end
end
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