Couldn't find Vehicle with 'id'= - ruby-on-rails

Question

Im trying to add service details for a vehicle. On the show page for my vehicle I've put a button which links to add new service details
<%= link_to 'Add Service Details', {:controller => :services, :action => :new, :vehicle_id => #vehicle.id}, {class: "btn btn-secondary"} %>
The url will show the vehicle_id like the following
http://localhost:3000/services/new?vehicle_id=3
on the _form.html.erb for services I've got
<div class="field">
<%= form.label :vehicle_id %>
<%= form.text_field :vehicle_id, id: :service_vehicle_id %>
</div>
In the controller I've got
def create
#vehicle = Vehicle.find(params[:vehicle_id])
#service = #vehicle.service.create(service_params)
redirect_to #service, notice: 'Service was successfully created.'
end
and
def new
#vehicle = Vehicle.find(params[:vehicle_id])
#service = Service.new
end
In my model I've defined the relationship as
Vehicle model
has_many :service
Service model
belongs_to :vehicle
My routes file looks like
resources :vehicles
resources :services
Can someone please help me use the vehicle_id and save it as a foreign key. I'm not sure if the above is the right approach but I'd like it so when the user views a vehicle they've got a button which allows them to add service details.

Answer 1

The user go to
http://localhost:3000/services/new?vehicle_id=3
in your controller the following code run
def new
#Serch for a vehicle
#vehicle = Vehicle.find(params[:vehicle_id])
# Create a Service object with no vehicle_id set
#service = Service.new
end
Like vehicle_id is not set then
<%= form.text_field :vehicle_id, id: :service_vehicle_id %>
should genarate a text field without value, when you submit the form
def create
# Here must throw an error
#vehicle = Vehicle.find(params[:vehicle_id])
#service = #vehicle.service.create(service_params)
redirect_to #service, notice: 'Service was successfully created.'
end
Go to the new action set the vehicle id
def new
#Serch for a vehicle
#vehicle = Vehicle.find(params[:vehicle_id])
# Create a Service object with no vehicle_id set
#service = Service.new
# Add vehicle id to service
#service.vehicle_id = #vehicle.id
end

Answer 2

If what you want is a form that you can place on show action of a vehicule to create a new service than what you want is just your run of the mill nested resource:
resources :vehicules do
resources :services, shallow: true
end
This will setup the routes so that you create a new service by POST'ing to /vehicules/:vehicule_id/services. Note that this puts the parent id in the path so that you don't need to send it as a hidden input.
For the form you just do:
<%= form_for([#vehicule, #service || Service.new]) do |f| %>
# inputs go here
<% end %>
# or with Rails 5 'form_with'
# form_with(model: #vehicule, url: [#vehicule, #service || Service.new])
You then setup the controller:
class ServicesController < ApplicationController
before_action :set_vehicule, only: [:new, :create, :index]
def new
#service = #vehicule.services.new
end
def create
#service = #vehicule.services.new(service_params)
if #service.save
# ...
else
# ...
end
end
def index
#services = #vehicule.services
end
# ...
private
def set_vehicule
#vehicule = Vehicule.find(params[:vehicule_id])
end
def service_params
# ...
end
end