How to set minimum and maximum number of tags?

Question

I am using acts-as-taggable-on gem and I am trying to make some sort of the validation on number of tags. I followed this tutorial and it works fine: http://railscasts.com/episodes/382-tagging

I have an article which acts as taggable. For now I validate that tags need to be present and number of characters:

class Article < ActiveRecord::Base
  acts_as_taggable
  validates :tag_list, presence: true, length: { maximum: 100 }
end

This is not really good solution for tags as there are many of them with many different sizes and they are separated by commas. How can I set required minimum and maximum number of tags which need to be connected with article? I would like to set minimum to 3 tags and maximum to 10 tags so length of text is not a good solution.

Thank you for your help :)

Answer 1

This example should point the right direction:

validate :tag_list_validation

def tag_list_validation
  errors[:tag_list] << "3 tags minimum" if tag_list.count < 3
  errors[:tag_list] << "10 tags maximum" if tag_list.count > 10
  self.tag_list.each do |tag|
    errors[:tag_list] << "#{tag} must be shorter than 100 characters maximum" if tag.length > 100
  end
end

EDIT: Solution to your question:

class Article < ActiveRecord::Base
  acts_as_taggable

  validate :tag_list_count

  def tag_list_count
    errors[:tag_list] << "3 tags minimum" if tag_list.count < 3
    errors[:tag_list] << "10 tags maximum" if tag_list.count > 10
  end
end