Rails - Convert hours and minutes to seconds then assign value to key - ruby-on-rails

Question

I would like to combine both values :hours and :minutes and convert them to to_i in seconds. Next is to assign this value (which should be in seconds) to the :time_duration which is a column in the cars db before it creates a new service. The :time_duration is in a hidden_field because there's no reason to render this data in the view.
views
This is my _car_fields.html.erb which is a nested partial inside a view template called, _form.html.erb .
_car_fields.html.erb
<div class="nested-fields">
<div class="field">
<%= f.label :name %><br>
<%= f.text_field :name %><br>
<%= f.label :hours %>
<%= f.select :hours, '0'..'8' %>
<%= f.label :minutes %>
<%= f.select :minutes, options_for_select( (0..45).step(15), selected: f.object.minutes )%><br>
<%= f.label :price %><br>
<%= f.text_field :price, :value => (number_with_precision(f.object.price, :precision => 2) || 0) %> <br>
<%= f.label :details %><br>
<%= f.text_area :details %></div>
<%= link_to_remove_association "Remove Car", f, class: 'btn btn-default' %>
<%= f.hidden_field :time_duration, value: %>
<br>
<hr>
</div>
_form.html.erb
<%= simple_form_for #service do |f| %>
<div class="field">
<%= f.label "Select service category" %>
<br>
<%= collection_select(:service, :service_menu_id, ServiceMenu.all, :id, :name, {:prompt => true }) %>
<%= f.fields_for :cars do |task| %>
<%= render 'car_fields', :f => task %>
<% end %>
</div>
<div class="links">
<%= link_to_add_association 'Add New Car', f, :cars, class: 'btn btn-default' %>
</div><br>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
controller
services_controller
def new
#service = current_tech.services.build
end
def create
#service = current_tech.services.build(service_params)
respond_to do |format|
if #service.save
format.html { redirect_to #service, notice: 'Service was successfully created.' }
format.json { render :show, status: :created, location: #service }
else
format.html { render :new }
format.json { render json: #service.errors, status: :unprocessable_entity }
end
end
end
private
def service_params
params.require(:service).permit(:name, :service_menu_id, cars_attributes: [:tech_id, :name, :hours, :minutes, :price, :details, :_destroy])
end
models
service.rb
class Service < ActiveRecord::Base
belongs_to :tech
belongs_to :service_menu
has_many :cars, dependent: :destroy
accepts_nested_attributes_for :cars, :reject_if => :all_blank, :allow_destroy => true
end
car.rb
class Car< ActiveRecord::Base
belongs_to :service
belongs_to :tech
has_many :appointments
end

Answer 1

First, you can remove the hidden time_duration field from the form, since it is not needed.
Then, you'll create a before_save method for your car model:
car.rb
class Car < ActiveRecord::Base
belongs_to :service
belongs_to :tech
has_many :appointments
before_save :generate_time_duration
def generate_time_duration
self[:time_duration] = hours.hours.to_i + minutes.minutes.to_i
end
end
What this does: Before the car object is saved, it will run the generate_time_duration method. What this method does is it simply sums the hours.to_i and minutes.to_i and assigns it to the car's time_duration attribute.
Update old DB records
Since you're adding this functionality in your application AFTER records have already been created, here is a quick way to update all of your current records:
In your command line, open a rails console by running the command rails c (or rails console)
In the console, run this command: Car.all.each { |c| c.save! }
This is a quick, one-time fix that will loop through all Car records, save them, and subsequently update their time_duration fields.