Question

Is there any way to initialize a model object like:

@review = current_user.reviews.build(params[:review])

and then check it’s validity against the validation rules in review.rb?

…without attempting to save the model object to the DB??

Answer 1

You can use @review.valid? to check if the model is valid without saving it to the database.

if @review.valid?
  #Do something
end

PS: In fact you can add validations to any class without having to use database functionality by using ActiveModel::Validations. See Railscast #219 for an example.