ActiveModel attributes

Question

How do I get ActiveRecord attributes method functionality? I have this class:

class PurchaseForm
  include ActiveModel::Validations
  include ActiveModel::Conversion
  extend ActiveModel::Naming

  attr_accessor :name,
                :surname,
                :email

  validates_presence_of :name

  validates_format_of :email, :with => /^[-a-z0-9_+\.]+\@([-a-z0-9]+\.)+[a-z0-9]{2,4}$/i

  def initialize(attributes = {}, shop_name)
    if not attributes.nil?
      attributes.each do |name, value|
      send("#{name}=", value)
    end
  end

  def persisted?
    false
  end
end

What I need to do, to have an attributes method to list all names and values from PurchaseForm object?

Answer 1

Here is the refactored variant:

class PurchaseForm
  include ActiveModel::Model

  def self.attributes
    [:name, :surname, :email]
  end

  attr_accessor *self.attributes

  # your validations

  def to_hash
    self.class.attributes.inject({}) do |hash, key|
      hash.merge({ key => self.send(key) })
    end
  end  
end

Now you can easily work with this class:

irb(main):001:0> a = PurchaseForm.new({ name: 'Name' })
=> #<PurchaseForm:0x00000002606b50 @name="Name">
irb(main):002:0> a.to_hash
=> {:name=>"Name", :surname=>nil, :email=>nil}
irb(main):003:0> a.email = '[email protected]'
=> "[email protected]"
irb(main):004:0> a
=> #<PurchaseForm:0x00000002606b50 @name="Name", @email="[email protected]">
irb(main):005:0> a.to_hash
=> {:name=>"Name", :surname=>nil, :email=>"[email protected]"}

Even more, if you want to make this behaviour reusable, consider extraction of .attributes and #to_hash methods into separate module:

module AttributesHash
  extend ActiveSupport::Concern

  class_methods do
    def attr_accessor(*args)
      @attributes = args
      super(*args)
    end

    def attributes
      @attributes
    end
  end

  included do
    def to_hash
      self.class.attributes.inject({}) do |hash, key|
        hash.merge({ key => self.send(key) })
      end
    end
  end
end

Now, just include it to your model and you're done:

class PurchaseForm
  include ActiveModel::Model
  include AttributesHash

  attr_accessor :name, :surname, :email

  # your validations
end