Question

I want to implement a method that checks if a model’s instance has only nil or empty attributes, except from its id or timestamps.

I’ve made use of an auxiliary method that removes a key from Hash and return the remaining hash ( question 6227600)

class ActiveRecord::Base
    def blank?
        self.attributes.remove("id","created_at","updated_at").reject{|attr| self[attr].blank?}.empty?
    end
end

I guess that there may be much simpler, efficient or safer way to do this. Any suggestion?

Answer 1

def blank?
  self.attributes.all?{|k,v| v.blank? || %w(id created_at updated_at).include?(k)}
end

My response is almost the same that tadman gave, but expressed in a more concise way.
Be careful with two situations:

– **blank?** is not a good choice as name, since if you call **object_a.object_b.blank?** trying to know if there is or not a object_b inside object_a, you’ll get true event if the object exists. **empty?** seems a better name

– If databases sets defaults values, it can be tricky.

EDIT: Since build an array every iteration is slow (thanks tadman), a beter solution is:

def empty?
  ignored_attrs = {'id' => 1, 'created_at' => 1, 'updated_at' => 1}
  self.attributes.all?{|k,v| v.blank? || ignored_attrs[k]}
end