Rails 4: form_for with nested model - ruby-on-rails

Question

I have three models: Client, Car, and ParkingRate. Client has many cars, and car has many parking_rates. I have a form on the client page that creates a car associated with that client. What I don't know how to do is to add a field for parking_rate to that form, so that when a car is created for that client, a parking rate is also created for that car.
My code looks like:
client.rb
class Client < ActiveRecord::Base
has_many :cars, dependent: destroy
end
car.rb
class Car < ActiveRecord::Base
belongs_to :client
has_many :parking_rates
end
parking_rate.rb
class ParkingRate < ActiveRecord::Base
belongs_to :car
end
On the client page (client/:id), I have a form to create a car associated with that client, like this:
views/clients/show.html.erb:
<h1>Client information</h1>
... client info ...
<%= render 'cars/form' %>
views/cars/_form.html.erb:
<%= form_for([#client, #client.cars.build]) do |f| %>
<p>
<%= f.label :vehicle_id_number %><br>
<%= f.text_field :vehicle_id_number %>
</p>
<p>
<%= f.label :enter_date %><br>
<%= f.text_field :enter_date %>
</p>
<p>
<%= f.submit %>
</p>
<% end %>
The Clients and Cars controllers look like this:
clients_controller.rb:
class ClientsController < ApplicationController
def new
#client = Client.new
end
def create
#client = Client.new(client_params)
if #client.save
redirect_to #client
else
render 'new'
end
end
def show
#client = Client.find(params[:id])
end
def index
#clients = Client.all
end
def edit
#client = Client.find(params[:id])
end
def update
#client = Client.find(params[:id])
if #client.update(client_params)
redirect_to #client
else
render 'edit'
end
end
def destroy
#client = Client.find(params[:id])
#client.destroy
redirect_to clients_path
end
private
def client_params
params.require(:client).permit(:first_name, :last_name)
end
end
cars_controller.rb:
class CarsController < ApplicationController
def create
#client = Client.find(params[:client_id])
#car = #client.cars.create(car_params)
#parking_rate = #car.parking_rates.create(rate_params)
redirect_to client_path(#client)
end
def show
#client = Client.find(params[:client_id])
#car = Car.find(params[:id])
end
def edit
#client = Client.find(params[:client_id])
#car = Car.find(params[:id])
end
def update
#client = Client.find(params[:client_id])
#car = Car.find(params[:id])
#car.update(car_params)
redirect_to client_path(#client)
end
def destroy
#client = Client.find(params[:client_id])
#car = #client.cars.find(params[:id])
#car.destroy
redirect_to client_path(#client)
end
private
def car_params
params.require(:car).permit(:vehicle_id_number, :enter_date, :rate)
end
def rate_params
params.require(:parking_rate).permit(:rate)
end
end
With this I am able to add cars to a given client, but I would also like to add a parking_rate to a car on the same form. So right when I create a car using this form, I want to create an associated parking rate. The form_for helper uses a [#client, #client.comments.build] as the model object, so I am not sure how to reference the parking_rate model in the same form. I think the solution is to use a fields_for helper, what would be the model reference for that, and what would I need to add to the cars and client controllers?

Answer 1

In client.rb, add the line
accepts_nested_attributes_for :cars