HStore accessor: Postgres, Rails

hstore_accessor_for_model.rb

  def hstore_get(field_name)
    method(field_name).call
  end
  def hstore_set(field_name,value)
    method("#{field_name}=").call(value)
  end
  
  def hstore_accessor(field_name,name)
    define_method(name) do
      hstore = hstore_get(field_name)
      hstore && hstore[name]
    end
    define_method("#{name}=") do |value|
      hstore = hstore_get(field_name) || {}
      hstore_set field_name, hstore.merge( name => value )
    end
    define_method("#{name}_present?") do
      hstore = hstore_get(field_name)
      hstore && hstore.has_key?(name)
    end
  end

hstore_migration.rb

class CreateXxx < ActiveRecord::Migration
  def change
    create_table :xxxs do |t|
      t.hstore :params
    end
    add_index "xxxs", ["params"], name: "xxxs_gin_params", using: :gin
  end
end