Is there a way to make Rails ActiveRecord attributes private?

Question

By default, ActiveRecord takes all fields from the corresponding database table and creates public attributes for all of them.

I think that it's reasonable not to make all attributes in a model public. Even more, exposing attributes that are meant for internal use clutters the model's interface and violates the encapsulation principle.

So, is there a way to make some of the attributes literally private?

Or, maybe I should move on to some other ORM?

Answer 1

Jordini was most of the way there

Most of active_record happens in method_missing. If you define the method up front, it won't hit method_missing for that method, and use yours in stead (effectively overwriting, but not really)

class YourModel < ActiveRecord::Base

  private

  def my_private_attribute
    self[:my_private_attribute]
  end

  def my_private_attribute=(val)
    write_attribute :my_private_attribute, val
  end

end

Answer 2

well, you could always override the methods...

class YourModel < ActiveRecord::Base

  private

  def my_private_attribute
    self[:my_private_attribute]
  end

  def my_private_attribute=(val)
    self[:my_private_attribute] = val
  end

end

Answer 3

Stumbled upon this recently. If you want private writing and reading and public reading something like this

class YourModel < ActiveRecord::Base

  attr_reader :attribute

  private

  attr_accessor :attribute


end

seems to work fine for me. You can fiddle with attr_reader, attr_writer and attr_accessor to decide what should be exposed and what should be private.

Answer 4

You can make an existing method private:

YourClass.send(:private, :your_method)

Answer 5

For me methods from both Otto and jordinl are working fine and make rspec for object of Class to pass:

object.should_not respond_to :attribute

But when I use jordinl method, I have a deprecation message to not write to database directly, but use attr_writer instead.

UPDATE:

But the truly "right" metod to do it turns out to be simple. Thanks to Mladen Jablanović and Christopher Creutzig from here. To make predefined method private or protected... simply redefine it:

Class Class_name

  private :method_name
  protected :method_name_1
end

What's important, you needn't rewrite previously defined method's logic.

Answer 6

Making the setting private does generate ActiveRecord error.

I put access control code in the overwritten method of the public setter by checking the caller:

def my_private_attribute=(val)
  if (caller.first.include?('active_record/base.rb') || caller.first.include?('app/models/myclass.rb'))
    self[:my_private_attribute] = val
  else
     raise Exception.new("Cannot set read-only attribute.")
  end
end

Answer 7

I don't think there is 100% reliable way to do this. It's also worth checking the most popular ways to access attributes:

http://www.davidverhasselt.com/set-attributes-in-activerecord/