How to use ActiveModel::EachValidator in rails 5

Question

How to validate specific attribute using ActiveModel::EachValidator. I have written the below snippet of code. This validation will not call on saving or validating object.

class EmailValidator < ActiveModel::EachValidator
    def validate_each(record,attribute,value)
       # Logic to check email is valid or not
    end
end

This will work with rails 3.

Answer 1

A simple base class that can be used along with ActiveModel::Validations::ClassMethods#validates_with

class User
  include ActiveModel::Validations
  validates_with EmailValidator
end

class EmailValidator < ActiveModel::Validator
  def validate(record)
     # Logic to check email is valid or not
     record.errors.add :email, "This is some complex validation"
  end
end

Any class that inherits from ActiveModel::Validator must implement a method called validate which accepts a record.

To cause a validation error, you must add to the record's errors directly from within the validators message.

For more details you can check here.

If you are looking for only email validation then you can try this.

class EmailValidator < ActiveModel::EachValidator
  def validate_each(record, attr_name, value)
    unless value =~ /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i
      record.errors.add(attr_name, :email, options.merge(:value => value))
    end
  end
end