ApplicationForm

Painless forms for ActiveRecord. Based on Inheritance. Included:

• Strong parameters
• Validation (based on the model validation)
• Data normalization

Add this line to your application's Gemfile:

gem 'application_form'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install application_form

1. Create directory app/forms
2. Add Form class for a model
3. Add permitted params inside the class
4. Use it as a normal model (without strong_params)

Use the supplied generator to generate forms:

$ rails g application_form:form sign_up --model=user

or with namespace model

$ rails g application_form:form admin_post --model=blog/post

# app/forms/user_sign_up_form.rb
class UserSignUpForm < User
  include ApplicationForm

  # list all the permitted params
  permit :first_name, :email, :password

  # add validation if necessary
  # they will be merged with base class' validation
  validates :password, presence: true

  # optional data normalization
  def email=(email)
    if email.present?
      write_attribute(:email, email.downcase)
    else
      super
    end
  end
end

form = UserSignUpForm.new(user_params)
form.valid?

In some cases it is necessary to use ActiveRecord object directly without form. For such cases conveniently to use method becomes() (built-in ActiveRecord):

user = User.find(params[:id])
form = user.becomes(UserSignUpForm)

Checks are build on top of Rails validations. They are semantically separated from validations, because we treat them as business logic checks, not as data validation.

class ReservationCreateForm < Reservation
  include ApplicationForm

  permit :user_id, :vehicle_id, :start_at, :end_at, :pickup_location_id, :return_location_id

  check :max_number_of_reservations_reached, ->(form) { !form.user&.reservations_limit_reached? }
  check :car_is_on_maintenance, ->(form) { form.vehicle&.reservable? }
end

# In controller:
form = ReservationCreateForm.new(prepared_params)

if form.checks_passed?
  # ...
else
  render_error!(form.first_failed_check) # form.first_failed_check returns "reservation.error.max_number_of_reservations_reached"
end

You can also assign check to a specific field:

check :end_at_must_be_greater_then_start_at, ->(form) { form.end_at > form.start_at }, :end_at

In this case it will work as a regular validation.

It works as regular assign_attributes but it also returns the object, so that you can chain it:

form = current_user.becomes(UserApplyReferralProgramForm)
                   .assign_attrs(registration_referral_code: referral_code)

It is a usual pattern when you use for in #update action.

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

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

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

Everyone interacting in the ApplicationForm project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.