Best approach to save user preferences? [closed]

It's usually a good idea to favor normalization. The second solution keeps your models cleaner, allows for easy extensibility if new preferences are added, and keeps your tables uncluttered.

I grappled with this same question so I thought I'd share what I found in a "community wiki" answer.

Serializing in a single attribute

Simple user preferences for your Rails app is a blog post describing how to do this.

Edit a serialized hash in a form? describes how to edit such a hash in a form. A helpful trick is to make the form from OpenStruct.new(@user.preferences) hash to automatically make accessor methods for each hash attribute.

DYE/has_serialized - GitHub lets you treat those attributes in the serialized hash as attributes on the (user) model.

Preferences in a separate table

Best practice to store user settings? has some tips. Below are some libs including two from another answer by @hopeless.

• rails-settings manages a table of key/value pairs like a Hash stored in you database, using simple ActiveRecord like methods for manipulation. You can store any kind of object: Strings, numbers, arrays, or any object which can be noted as YAML. (Tested with Rails 3.1 and newer including Rails 4.x and Rails 5.x)
• Preference-fu is good for simple boolean preferences, uses a single column for multiple preferences.(last updated 2009)
• Preferences is more flexible, uses a separate table, some nice syntactic sugar. (last updated 2011)
• HasEasy stores the data in a vertical table, but allows you to add validations, pre/post storage processing, types, etc. (Last updated 2008)

You can also try using metaprogramming: Practical Metaprogramming with Ruby: Storing Preferences

An improved version of the first approach can be had if you're on PostgreSQL 9.2/3+ and Rails 4+. You can use store_accessor to store preferences in a PostgreSQL hstore column with support for validations and querying.

class User
  store_accessor :preferences, :receive_newsletter

  validates :receive_newsletter, presence: true
end

user.receive_newsletter => 'true'

User.where("preferences->'receive_newsletter' = 'true'")

See http://mikecoutermarsh.com/using-hstore-with-rails-4/ for more details (migrations) and a special note on handling booleans.