A better validates_associated

As you may very well know, validates_associated is good, but not great. Yes, it does ensure that your related models adhere to the rules in your multi-model form. But there are two fundamental problems with it:

1. The actual error messages are useless (i.e. “[Model] is invalid”) — I’d like to know why it’s invalid
2. Redundant messages for each and every invalid associated model

The first, everyone can agree on. So let’s fix that one right away:

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# config/initializers/validation_fixes.rb
module ValidatesAssociatedAttributes
  module ActiveRecord::Validations::ClassMethods
    def validates_associated(*associations)
      class_eval do
        validates_each(associations) do |record, associate_name, value|
          (value.respond_to?(:each) ? value : [value]).each do |rec|
            if rec && !rec.valid?
              rec.errors.each do |key, value|
                record.errors.add(key, value)
              end
            end
          end
        end
      end
    end
  end
end

There, now you’ll get the true error messages. For example, “[Model] is invalid” now becomes “[Model] is not formatted properly”, or the like.

Now, onto the second one. I find that most of my multi-model forms have more than one nested model. To save you from a contrived example, let’s use Golf Trac. Well, a course has 4 different sets of 18 yardages (72 yardages), 2 sets of 18 handicaps, 18 par ratings, then 1 rating and 1 slope for each of the 4 possible tees (black, blue, white, red). That’s a total of (I think) 134 fields on a course (I know, that’s why courses are now reusable).

So, the course form, when submitted, gets split out into three tables: courses, tees, and holes, each with their own validation rules. Let’s say a user submits a blank form. Originally, validates_associated would say “Hole is invalid” a gajillion times. That’s stupid in my case. I’d rather it just say “Par cannot be blank” and/or “Par must be a number” one time each. So, combined with step #1, I did something like this:

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# config/initializers/validation_fixes.rb
class ActiveRecord::Errors
  alias old_full_messages full_messages
  def full_messages
    old_full_messages.uniq
  end
end

Now I get much better error messages and I’m only yelling at the user one time.