How to add to the form a virtual fields

Question

Starting to learn the Ruby on Rails.
How to add to the form a virtual fields?
After submitting the form, these fields must be combined and stored in a single database field.

Answer 1

First set up your form as usual:

<%= form_for @user do |f| %>
<ol>
  <li>
    <%= f.label :first_name, 'First Name' %>
    <%= f.text_field :first_name %>
  </li>
  <li>
    <%= f.label :last_name, 'Last Name' %>
    <%= f.text_field :last_name %>
  </li>
  <%= f.submit %>
</ol>
<% end %>

In this example we are adding a virtual attribute for first_name and last_name.

user.rb

class User < ActiveRecord::Base
  attr_accessor :first_name
  attr_accessor :last_name
end

Add an attr_accessor for your new virtual attribute.

users_controller.rb

def create
  @user = User.new(:full_name => {'firstname' => user_params[:first_name], 'lastname' => user_params[:last_name]})
  ...
end

private

def user_params
  params.require(:user).permit(:first_name, :last_name)
end

Finally, add a method to permit the virtual attribute params (assuming Rails 4).

To save multiple inputs and save them into a single field in the DB you can combine the virtual fields in the controller and then save them to the DB, as shown in the create method above.