Question

I have a standard active record model with an attributes that is required:

class Sample < ActiveRecord::Base
  has_many :colors

  before_validation :grab_colors

  validates_presence_of :size
  validate :number_of_colors

  private

  def grab_colors
    # grab x number of colors | x = size
  end

  def number_of_colors
    self.errors.add("size","is to large.") if colors.count < size
  end
end

My problem is that the grab_colors method requires the size attribute but performs a result that needs to be validated as well. In the case above size is used before it’s presence is validated.

Can I set the instance as invalid and stop the save process after all validation have been made?

Answer 1

I am assuming that you want the number_of_colors method to run after the grab_colors method. In that case I would recommend calling both methods in order from a validate method.

def validate
  unless size.blank?
    grab_colors 
    number_of_colors
  end
end

The validation of size is still handled by

validates_presence_of :size

But if you have size then grab_colors and number_of_colors run. Now you won’t need these lines

before_validation :grab_colors
validate :number_of_colors