Render action with parameters after form error - ruby-on-rails

Question

I have basic form that is accessed, for example via: http://url.com/rentals/new/dvd/10.
The problem is when form error happens I can't redirect it to the same page with the same
url segments and show the form error messages.
rentals_controller.rb:
def create
#rental = Rental.new(rental_params)
respond_to do |format|
if #rental.save
format.html { redirect_to #rental, notice: 'Rental was successfully created.' }
format.json { render :show, status: :created, location: #rental }
else
format.html { render :new }
format.json { render json: #rental.errors, status: :unprocessable_entity }
end
end
end
routes.rb
get 'rentals/new/dvd/:dvd_id' => 'rentals#new', as: :new_dvd_rental
I have the following models created:
dvd.rb
class Dvd < ActiveRecord::Base
has_many :rentals
has_many :users, through: :rentals
validates :title, presence: true
validates :year, inclusion: {in: 1900..Time.now.year.to_i}, :presence => {:message => 'Year must be from 1900 till current year.'}
validates :length, inclusion: {in: 1..999}, :presence => {:message => 'DVD length must be in minutes in range 1..999.'}
end
rental.rb
class Rental < ActiveRecord::Base
belongs_to :user
belongs_to :dvd
validates :user_id, presence: true
validates :total_price, presence: true
end
user.rb
class User < ActiveRecord::Base
has_many :rentals
has_many :dvds, through: :rentals
end
As well as rentals_controller.rb:
class RentalsController < ApplicationController
before_action :set_rental, only: [:show, :edit, :update, :destroy]
# GET /rentals
# GET /rentals.json
def index
#rentals = Rental.all
end
# GET /rentals/1
# GET /rentals/1.json
def show
end
# GET /rentals/new
def new
#rental = Rental.new
#users = User.all
#dvd = Dvd.find(params[:dvd_id])
end
# GET /rentals/1/edit
def edit
end
# POST /rentals
# POST /rentals.json
def create
#rental = Rental.new(rental_params)
respond_to do |format|
if #rental.save
format.html { redirect_to #rental, notice: 'Rental was successfully created.' }
format.json { render :show, status: :created, location: #rental }
else
format.html { render :new }
format.json { render json: #rental.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /rentals/1
# PATCH/PUT /rentals/1.json
def update
respond_to do |format|
if #rental.update(rental_params)
format.html { redirect_to #rental, notice: 'Rental was successfully updated.' }
format.json { render :show, status: :ok, location: #rental }
else
format.html { render :edit }
format.json { render json: #rental.errors, status: :unprocessable_entity }
end
end
end
# DELETE /rentals/1
# DELETE /rentals/1.json
def destroy
#rental.destroy
respond_to do |format|
format.html { redirect_to rental_url, notice: 'Rental was successfully deleted.' }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_rental
#rental = Rental.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def rental_params
params.require(:rental).permit(:dvd_id, :user_id, :rent_date, :return_date, :total_price, :returned)
end
end
I've tried to modify rental controller like this, but still do not know how to pass other segments like new and dvd:
render :action => "new", :dvd_id => params[:dvd_id]
Any ideas?

Answer 1

I think if you draw a more restful route like this
resources :dvds do
resources :rentals
end
you will get the routes like http://url.com/dvd/10/rentals/new
here you will always get dvd_id
and in rentals_controller create method look like
def create
#dvd = Dvd.find(params[:dvd_id])
#rental = Rental.new(rental_params)
respond_to do |format|
if #rental.save
format.html { redirect_to #rental, notice: 'Rental was successfully created.' }
format.json { render :show, status: :created, location: #rental }
else
format.html { render :new }
format.json { render json: #rental.errors, status: :unprocessable_entity }
end
end
end

Answer 2

-- Waiting for #Sanket's ideas
Routes
The issue will almost certainly be with your redirect_to method
The problem is that your controller doesn't know you're using a nested resource, and consequently when you redirect to an object, it will likely just take you to the simplest route it can find
I would try this:
def create
...
else
format.html { render your_nested_resource_path(dvd_id: params[:dvd_id], other: params[:params]) }
...
end
This allows you to send the request to the nested route, which Rails won't route to without support