Model preferences allow you to easily extend Spree models with configuration options. Thanks to this you can store useful information on Spree models, eg. 
user.preferred_language = "English"
user.save

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Defining Model Preferences

To define a model preference, you need to add them to your model class. Make sure to generate a migration to add the preferences column to the table. This column will store the preferences in a serialized format. 
rails g migration AddPreferencesToSpreeUsers preferences:text
Run the migration. 
rails db:migrate

class Spree::User < ApplicationRecord
  # ... you existing code ...

  # include the preferable module
  include Spree::Preferences::Preferable
  # define the preferences
  preference :language, :string, default: "English"
  preference :sms_marketing, :boolean, default: false
end
This will add a language preference to the User model. The preference will be stored in the newly created preferences column of the spree_users table. You can add more preferences to the model in the same way.

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Accessing Model Preferences

Once preferences have been defined for a model, they can be accessed either using the shortcut methods that are generated for each preference or the generic methods that are not specific to a particular preference.

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Shortcut Methods

There are several shortcut methods that are generated. They are shown below. Query methods: 
user.prefers_sms_marketing? # => false
Reader methods: 
user.preferred_sms_marketing      # => false
user.preferred_language   # => "English"
Writer methods: 
user.prefers_sms_marketing = false         # => false
user.preferred_language = "English"    # => "English"
Remember to run user.save after setting the preference value to save the changes to the database.
Check if a preference is available: 
user.has_preference? :sms_marketing

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Generic Methods

Each shortcut method is essentially a wrapper for the various generic methods shown below: Query method: 
user.prefers?(:sms_marketing)       # => false
user.prefers?(:language)  # => false
Reader methods: 
user.preferred(:sms_marketing)      # => false
user.preferred(:language)   # => "English"

user.get_preference :sms_marketing
user.get_preference :language
Writer method: 
user.set_preference(:sms_marketing, false)     # => false
user.set_preference(:language, "English")  # => "English"

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Accessing All Preferences

You can get a hash of all stored preferences by accessing the preferences helper: 
user.preferences # => {"language"=>"English", "sms_marketing"=>false}
This hash will contain the value for every preference that has been defined for the model instance, whether the value is the default or one that has been previously stored.

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Models with preferences

The following Spree models already have preferences defined:
  • Spree::Calculator
  • Spree::Gateway
  • Spree::PageBlock
  • Spree::PageSection
  • Spree::Page
  • Spree::PaymentMethod
  • Spree::PromotionRule
  • Spree::Store
  • Spree::Theme