Where to perform validation <p>If I have two models, and am using <code>accepts_nested_attributes_for</code> where should I be putting my validations for the child model.</p> <p>For example; if I want to validate the images size and limit (ie only allow the user to upload 3 images) should I be validating in the Animal or AnimalImage model</p> <pre><code>class Animal &lt; ActiveRecord::Base has_many :animal_images, dependent: :destroy accepts_nested_attributes_for :animal_images, allow_destroy: :true end class AnimalImage &lt; ActiveRecord::Base mount_uploader :image, AnimalImageUploader belongs_to :animal end </code></pre> <p>I am using carrierwave to upload my images. I have noticed they have some built in helper methods but from the examples I have seen the image is always in the parent model (ie a user having an avatar)</p> <p>Any help appreciated</p> <p>Thanks</p>