If you have an attribute that needs to be saved and retrieved to database as an object, then specify the name of that attribute using the serialize method and it will be handled automatically.

The attribute must be declared as a text field.

In the model you must declare the type of the field (Hash or Array)

More info at: serialize >> apidock.com (opens new window)

In your migration

class Users < ActiveRecord::Migration[5.0]
  def change
    create_table :users do |t|
      ...
      t.text :preference
      t.text :tag
      ...
      t.timestamps
    end
  end
end

In your model

class User < ActiveRecord::Base
    serialize :preferences, Hash  
    serialize :tags, Array
end

Syntax

• serialize: <field_plural_symbol>