How can I store a regex expression string in a helper method to use to validate several different fields?

Question

I have several different fields that store different phone numbers in my rails app as a string. I can use the built-in rails format validator with a regex expression. Is there a way to place this expression in a helper method for all my phone number validations instead of having to open each model file and paste the expression string.

Answer 1

You can require any file from application.rb:

# application.rb
require Rails.root.join "lib", "regexes.rb"

# lib/regexes.rb
PHONE_NUMBER_REGEX = /your regex/

Then you simply use the constant wherever needed

You can alternatively make use of the built in autoload functionality of Rails, for example with the concern approach the other commenter laid out - the concern file is autoloaded by default, as are models, controllers, etc

Loading custom files instead of using the Rails' defaults might not seem idiomatic or the "rails way". However, I do think it's important to understand that you can load any files you want. Some people autoload the entire lib/ folder and subfolders (see Auto-loading lib files in Rails 4)

Another alternative is to place your code somewhere in the config/initializers folder, these files are automatically loaded at startup and you can define shared classes/modules/constants there

Answer 2

Add a custom validator app/validators/phone_validator.rb

class PhoneValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    unless value.to_s =~ /YOUR_REGEX_HERE/
      record.errors.add attribute, 'must be a valid phone number'
    end
  end
end

Then in your models

class MyModel < ApplicationRecord
  #phone: true tells it to use the PhoneValidator defined above
  validates :phone_number, presence: true, phone: true 
end

Answer 3

One way to do this is to create a concern that will be included in each model that has a phone number. In models/concerns, create a new file called something like phonable.rb.

# models/concerns/phonable.rb

module Phonable
  extend ActiveSupport::Concern

  VALID_PHONE_REGEX = /\A\+?\d+\z/ # Use your regex here

end

Now include the concern like this:

# models/my_model.rb

class MyModel < ApplicationRecord
  include Phonable

  validates :phone, format: {with: VALID_PHONE_REGEX}
  ...

end

Now that you have a Phonable concern, you can put any other phone-number-related logic here as well, such as parsing and the like. The advantage of this approach is that all your logic related to phone numbers will be available for use in the models that need it, and none of that logic will be available in models that don't need it.

Answer 4

You can put it in ApplicationRecord (application_record.rb)

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true

  VALID_PHONE_NUMBER_REGEX = /\d{10}/ # your regex here
end

And then you can use it in any model that inherits fro ApplicationRecord