Thoughts on ActiveModel::Validator as a validation service

use_validation_helpers.rb

# I love the helpers, they help to make the intention clear.
# I want to be able to do this. That is, using the validation helpers inside a validator object,
# rather than having to do manual validation.

class EmployeeValidator < ActiveModel::Validator
  def validate(record)
    record.validates_presence_of :email
  end
end

# After some reading, I realize I can do this

class EmployeeValidator < ActiveModel::Validator
  def setup(employee_class)
    user_class.validates_presence_of :email
  end

  def validate(record)    
  end
end

# This provides the ability to use the helpers from a validator object.

# Now, I'm working on a way to bypass the validations from examples 
# that aren't concerned with the validity of an object, such scope examples.
# Unfortunately, the setup method is called once when validates_with is called
# since ActiveRecord caches the validation objects. So, it has already been called
# and configured with the validation before a non-validation-oriented example
# can use it. So, no over-riding.

# Looking at the way validation helpers work, they all are backed by a subclass of
# Validator (or EachValidator), so you should be able to instantiate one and use it.


class EmployeeValidator < ActiveModel::Validator
  def validate(record)
    ActiveModel::Validations::PresenceValidator.new(attributes: [:first_name]).validate record
  end
end

# This works for doing the validation.

# Yes, this is ugly, but we can wrap it in a helper, perhaps even having Active Record models
# expose the helpers on an instance level.

# However, when our example runs that wants to bypass them, it keeps using the old version.
# I want to be able to do this at the top of my validation-less example.

class EmployeeValidator < ActiveModel::Validator
  def validate(record); end
end

# But, because the instance of the validator is cached when validates_with EmployeeValidator is
# called, my over-ride does not cut in. Boo!

# ActiveModel::Validations uses hooks to call the validations.
# Is there a way to disable the hook for a single example?

FYI that's how it's gonna work in DM2. We're moving away from validations being mixed into domain models.

Cool. ActiveModel::Validator looks nice, and I've got this working, now just figuring out how to disable them if I don't want them.

What do you think about the idea that one of a number of User validation classes could be used in different contexts.
I'm starting to think it could be an anti-pattern. If there are different validation rules based on the context, then the User model should probably be broken up.

@codesoda Yeah, it does feel like an anti-pattern to have different validations based on different contexts of use. In production, you want the validations to run, it is just in the example (e.g. scope specs) that I don't want them to run.

@coreyhaines I knew if I creeped up in your gists I'd find something like this. Did you figure out how to disable in a test context?

I like the helpers as well but am thinking a PORO approach may be easier. Inject a NilValidator in some kind of test context. Currently working on this so I'll post whatever I come up with.