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

Answer 2

You can put your EmailValidator class inside the models/concerns directory. Then inside your model you can validate the email attribute using the example below.

 class User < ApplicationRecord
   validates :email, presence: true, email: true
 end

Rails will look for the EmailValidator class within the scope when it encounters email: true then validate the attribute using the validate_each method.