在 ActiveModel::EachValidator 中使用实例变量

Question

I faced with curious fact (for me) about using each validators. For example we have a some custom each validator and some model:

class Thing < ApplicationRecord
  validates :field, custom: true
end

class CustomValidator < ActiveModel::EachValidator
  def validate_each(record, _attribute, _value)
    @record = record
  end
end

I've found out that an instance of CustomValidator class will be created once when we call Thing model for the first time. It means that we will have same validator object for every Thing instance. And my question is: How do you think, can we use instance variables inside validators like this or not... because looks like validator object will be created only once, and, for example, if we will call Thing.first.valid? and then Thing.last.valid? the @record will have the same value before we reassign it.

Or maybe a separate validator object will be created for each client?

I just worry is it possible that we can face races around @record variable when several widgets will be validated at the same time?

Thnx

Answer 1

I found another way, just define the class with a class method "validate" and an instance method "validate", and use this class method like a block. So, we can move huge validation in class, use it shortly in model Thing, and use instance variable between validator methods

class Thing < ApplicationRecord
  validate MyCustomValidator
end

class MyCustomValidator
  def self.validate(record)
    new(record).validate
  end

  def initialize(record)
    @record = record
  end

  def validate
    # some payload with @record
    validate_breakdowns
    validate_indicators
  end

  private

  attr_reader :record

  def validate_breakdowns
    # some payload with @record
  end

  def validate_indicators
    # some payload with @record
  end
end