How can I skip before_validations in Rails?

Question

I have code that updates/fixes some model data in my before_validation callbacks.

However, I'd like to be able to still run validations to see if a model is ok as-is.

More specifically, i'd like to know if a record in the database is valid or not. So I'd like to be able to load a value and ask .valid? without having my callbacks run that would affect the answer.

So, I tried this (and a few variations) but it didn't work:

skip_callback :validation, :before, unless: ->{self.changed?}

The docs for skip_callback are poor, so I'm not sure I'm using it properly. Can this be made to work?

Thanks.

Answer 1

According to APIDock skip_callback takes callback_name , then *filter_lists as arguments (then a block).

filter_list must include your callback method name. Like this below.

class User < ActiveRecord::Base
  validates_presence_of :name
  before_validation :set_name

  skip_callback :validation, :before, :set_name, unless: -> { self.changed? }

  def set_name
    self.name ||= 'foobar'
  end
end

#<User:0x007ffcd7165248 id: 2, name: nil, created_at: Fri, 03 Feb 2017 01:10:37 UTC +00:00, updated_at: Fri, 03 Feb 2017 01:10:37 UTC +00:00>

User.find(2).valid? # returns false

user = User.find(2)
user.updated_at = Time.now
user.valid? # returns true, because it invokes :set_name before validation

Answer 2

You can skip any callback. You have to skip the callback and do the transaction and set the call back again. Model.skip_callback(:callback_name, :callback_position, :callback_action_name)

For eg.

class ModelName < ApplicationRecord 
    before_validation :validation_action
    
    def validation_action
    end 

end 

To skip this validation when calling ModelName

ModelName.skip_validation(:validation, :before, :validation_action)
ModelName.create!()
ModelName.set_validation(:validation, :before, :validation_action)

Similarly, you can skip all callbacks from here

Answer 3

.. I'd like to be able to .. ask .valid? without having my callbacks run that would affect the answer.

Make the validation conditional on an attr_accessor .

# banana.rb
attr_accessor :use_validation_callbacks
before_validation :derp, if: { |b| b.use_validation_callbacks }
def initialize(*)
  self.use_validation_callbacks = true
  super
end

# elsewhere
banana = Banana.new
banana.use_validation_callbacks = false
banana.valid?