NoMethodError undefined method `id' for nil:NilClass: - ruby-on-rails

Question

I know this kind of question is already answered multiple times but i seriously unable to figure it out what is causing a problem here, I am having trouble solving this problem. I keep getting the same error when i'm trying to create new registration ( http://localhost:3000/registrations/new?course_id=1 ) :
NoMethodError at /registrations
undefined method `id' for nil:NilClass
Here is my RegistrationsController:
class RegistrationsController < ApplicationController
before_action :set_registration, only: [:show, :edit, :update, :destroy]
def index
#registrations = Registration.all
end
def show
end
def new
#registration = Registration.new
#course = Course.new
#course = Course.find_by id: params["course_id"]
end
def create
#registration = Registration.new registration_params.merge(email: stripe_params["stripeEmail"], card_token: stripe_params["stripeToken"])
raise "Please Check Registration Errors" unless #registration.valid?
#registration.process_payment
#registration.save
redirect_to #registration, notice: 'Registration was successfully created.'
rescue Exception => e
flash[:error] = e.message
render :new
end
protect_from_forgery except: :webhook
def webhook
event = Stripe::Event.retrieve(params["id"])
case event.type
when "invoice.payment_succeeded" #renew subscription
Registration.find_by_customer_id(event.data.object.customer).renew
end
render status: :ok, json: "success"
end
private
def stripe_params
params.permit :stripeEmail, :stripeToken
end
def set_registration
#registration = Registration.find(params[:id])
end
def registration_params
params.require(:registration).permit(:course_id, :full_name, :company, :telephone, :email, :card_token)
end
end
My Registration Model:
class Registration < ActiveRecord::Base
belongs_to :course
def process_payment
customer_data = {email: email, card: card_token}.merge((course.plan.blank?)? {}: {plan: course.plan})
customer = Stripe::Customer.create customer_data
Stripe::Charge.create customer: customer.id,
amount: course.price * 100,
description: course.name,
currency: 'usd'
#Annotate Customer Id when Registration is Created
cusotmer_id = customer.id
end
def renew
update_attibute :end_date, Date.today + 1.month
end
end
Registration New.html.haml File :
%section#course-content
%section#ruby
%section.detailed-syllabus
.wrapper-inside
= form_for #registration, html: { class: "basic-grey" } do |f|
- if #registration.errors.any?
#error_explanation
%h2
= pluralize(#registration.errors.count, "error")
prohibited this registration from being saved:
%ul
- #registration.errors.full_messages.each do |message|
%li= message
.field
= f.hidden_field :course_id, value: #course.id
.field
= f.label :full_name
= f.text_field :full_name
.field
= f.label :company
= f.text_field :company
.field
= f.label :email
= f.text_field :email
.field
= f.label :telephone
= f.text_field :telephone
//‘Stripe.js’ will recognize the card data because we have marked the inputs with ‘data-stripe’ attribute as: number, cvv, exp-month and exp-year.
= javascript_include_tag "https://js.stripe.com/v2/"
:javascript
Stripe.setPublishableKey('#{Rails.application.secrets.stripe_publishable_key}');
= label_tag "Card Number", nil, required: true
.control-group
.controls
= text_field_tag :card_number, nil, class: "input-block-level", "data-stripe" => "number"
= label_tag "Card Verification", nil, required: true
.control-group
.controls
= text_field_tag :card_verification, nil, class: "input-block-level", "data-stripe" => "cvv"
= label_tag "Card Expires", nil, required: true
= select_tag :exp_month, options_for_select(Date::MONTHNAMES.compact.each_with_index.map { |name,i| ["#{i+1} - #{name}", i+1] }), include_blank: false, "data-stripe" => "exp-month", class: "span2"
= select_tag :exp_year, options_for_select((Date.today.year..(Date.today.year+10)).to_a), include_blank: false, "data-stripe" => "exp-year", class: "span1"
.actions
= f.submit "Registration Payment", class: "btn", style: "color: white;background: rgb(242, 118, 73);"
Does anyone know how to assist me in this? Greatly appreciate all the help.
Additional Can anyone please guide me through how to pass id between 2 models like this guy did between 2 models as he's creating a scaffold for one model but passing ID lets him create values for another model too without creating actions for another controller https://github.com/gotealeaf/stripe-basics.git
Edited:
GitHub Repository For This Code
https://github.com/ChiragArya/Stripe_CheckOut_Demo

Answer 1

From your comments, it appears the error is caused by :
#course.id being nil
The way to fix this is to ensure #course is defined properly. You need to do the following:
def new
#registration = Registration.new
#course = Course.find_by id: params["course_id"]
end
The other issue you have here is that your routes should be able to handle courses without having to append them with ?course_id=1:
#config/routes.rb
resources :registrations do
get :course_id, to: "registrations#new" #-> yoururl.com/registrations/:course_id
end
This will still give you the course_id param in the new action; just makes it more Rails.
--
Controller
You also need some structure in your code (you're aiming for fat model, thin controller). It looks like you're coming to Rails as a Ruby dev; you need to appreciate that Rails handles most of the exceptions etc for you.
Specifically, you need to look at how to remove code out of your actions:
def create
#registration = Registration.new registration_params
#registration.process_payment
if #registration.save
redirect_to #registration, notice: 'Registration was successfully created.'
else
# handle error here
end
end
private
def registration_params
params.require(:registration).permit(:course_id, :full_name, :company, :telephone, :email, :card_token).merge(email: stripe_params["stripeEmail"], card_token: stripe_params["stripeToken"])
end
-
`id' for nil:NilClass
Finally, you have to remember this error basically means the variable you're trying to invoke an action for is nil.
Ruby populates nil variables with a NilClass object, thus it's difficult to determine what the error actually is. All it means is that the variable you're trying to call a method on doesn't have the aforementioned method, as Ruby has populated it with the NilClass object.

Answer 2

Try changing Registration#new action to
def new
#course = Course.find(params[:course_id])
#registration = #course.registrations.new
end

Answer 3

add this in your def create
def create
#course = Course.find_by id: params["registration"]["course_id"]
#registration = Registration.new registration_params.merge(email: stripe_params["stripeEmail"], card_token: stripe_params["stripeToken"])
raise "Please Check Registration Errors" unless #registration.valid?
#registration.process_payment
#registration.save
redirect_to #registration, notice: 'Registration was successfully created.'
rescue Exception => e
flash[:error] = e.message
#course = Course.find_by id: params["registration"]["course_id"]
render :new
end