Submitting form data is a common feature of web applications – allowing users to submit their information and giving them feedback whether the information is valid or not.
ActiveRecord comes with a powerful set of validators for attributes on a persisted data model. When data is not persisted, or used for other non-active record purposes, Active Model Helper Modules reduce the complexity of validations on your plain old Ruby objects.
Create the routes needed for displaying the form object and posting the data
- Restrict resources to the routes you need using
# config/routes.rb resources :registration, only: [:new, :create]
Controller and Actions
Create a controller with
respond_withwill re-render the
newaction if there are any validation errors on the model
- If there are no errors on the model the visitor will be redirected to
showthe current resource. In this case the user will be redirected to
# app/controllers/registration_controller.rb class RegistrationsController < ApplicationController respond_to :html def new @registration = Registration.new end def create @registration = Registration.new(registration_params) @registration.register respond_with @registration, location: some_success_path end private def registration_params # ... end end
View with Registration Form
The view renders a web form with fields to submit.
- Use the ActiveModel object
@registrationin the form
- Form generates the endpoint
registration_pathand method of delivery
- Validation errors will display inline within the form just like ActiveRecord
# app/views/registration/new.html.erb <%= form_for @registration do |f| %> <%= f.label :first_name, 'First Name' %>: <%= f.text_field :first_name %> ... <%= f.submit %> <% end %>
Object with ActiveModel Conversion, Naming, and Validations
Use any of the ActiveRecord Validations in the model.
- Command pattern used when calling
- ActiveRecord validation syntax on attributes.
- ActiveModel::Model mixin includes modules, and includes an initialization method.
# app/models/registration.rb class Registration include ActiveModel::Model attr_accessor( :company_name, :email, :first_name, :last_name, :terms_of_service ) validates :company_name, presence: true validates :email, presence: true, email: true validates :first_name, presence: true validates :last_name, presence: true validates :terms_of_service, acceptance: true def register if valid? # Do something interesting here # - create user # - send notifications # - log events, etc. end end private def create_user # ... end end
- Keep business logic out of the Controller and Views
- Add validation support to plain Ruby object using ActiveModel includes
- Display data validation errors in the form
- Use ActiveModel naming conventions for generating form endpoints