attr_statements

AttrStatements

AttrStatements is a simple strong typed attributes generator on classes. It also add the ability to validate these attributes. These validations are extended with ActiveModel::Errors, so you can have a full integration with ActiveRecord. A typical usecase will be extending a serializer with AttrStatements in order to have automatic ActiveModel::Errors management.

Installation

Add this line to your application's Gemfile:

gem 'attr_statements', '~> 0.1.1'

And then execute:

$ bundle

Or install it yourself as:

$ gem install attr_statements

Usage

require 'attr_statements'

class Profile
  extend AttrStatements

  attr_statement :email, String, presence: true, length: { maximum: 15 }
  attr_statement :city,  String
end

Profile.attr_statements
# => [:email, :city]

profile = Profile.new
# => #<Profile:0x007fc83511e8b0>

profile.valid?
# => false

profile.errors.any?
# => true

profile.errors
# => #<ActiveModel::Errors:0x007fc82bec5d88 @base=#<Profile:0x007fc83511e8b0 @errors=#<ActiveModel::Errors:0x007fc82bec5d88 ...>>, @messages={:email=>["can't be blank"]}>

profile.errors.full_messages
# => ["Email can't be blank"]

profile.email = '[e-mail]'
# => "[e-mail]"

profile.valid?
# => false

profile.errors.full_messages
# => ["Email is too long (maximum is 15 characters)"]

profile.email = '[e-mail]'
# => '[e-mail]'

profile.valid?
# => true

profile.email = 42
# => 42

profile.valid?
# => false

profile.errors.full_messages
# => ["Email must be a String"]

Bonuses

Add translations

The type validation for example would need a translation (at least a default :en). Translation is compatible with I18n. So all we need, is a yml with:

en:
  errors:
    messages:
      type: 'must be a %{class}'

Inject AttrStatements errors within an ActiveRecord validation process

AttrStatements errors can be easily injected within an ActiveRecord validation processus. Here is an example:

Class User < ActiveRecord::Base
  serialize :profile_attributes, Profile

  after_validation :validate_profile_attributes

  private

  def validate_profile_attributes
    if profile_attributes && !profile_attributes.valid?
      # merge child errors with parent errors
      profile_attributes.errors.each do |k, v|
        errors.add("profile_attribute_#{k}", v)
      end
    end
  end
end

User will now have the :profile_attributes errors generated by AttrStatements on create, update. (see ActiveRecord::Validations#valid?)

Running tests

To run tests:

$ bundle exec rake spec

Running CI tools

To run rubocop:

$ rubocop

To run reek:

$ reek

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/SparkHub/attr_statements. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.