NoMethodError in Users#unsubscribe - ruby

Question

I am working on implementing unsubscribe link to my rails mailer. Unfortunately, my code breaks with this:
NoMethodError in Users#unsubscribe - undefined method `unsubscribe_hash' for nil:NilClass
which points to /app/views/users/unsubscribe.html.erb line #3
<h4>Unsubscribe from Mysite Emails</h4>
<p>By unsubscribing, you will no longer receive email...</p>
<%= simple_form_for(#user, unsubscribe_path(id: #user.unsubscribe_hash)) do |f| %>
<%= f.hidden_field(:subscription, value: false) %>
<%= f.submit 'Unsubscribe' %>
<%= link_to 'Cancel', root_url %>
<% end %>
my user_controller is as shown below
class UsersController < ApplicationController
protect_from_forgery
def new
#user = User.new
end
def create
#user = User.new(secure_params)
if #user.save
flash[:notice] = "Thanks! You have subscribed #{#user.email} for Jobs Alert."
else
flash[:notice] = 'Error Subscribing! Kindly check your email and try again.'
end
redirect_to root_path
end
def unsubscribe
user = User.find_by_unsubscribe_hash(params[:unsubscribe_hash])
#user = User.find_by_unsubscribe_hash(user)
end
def update
#user = User.find(params[:id])
if #user.update(secure_params)
flash[:notice] = 'Subscription Cancelled'
redirect_to root_url
else
flash[:alert] = 'There was a problem'
render :unsubscribe
end
end
private
def secure_params
params.require(:user).permit(:email, :subscription)
end
end
Route.rb
resources :users, only: [:new, :create]
get 'users/:unsubscribe_hash/unsubscribe' => 'users#unsubscribe', as: :unsubscribe
patch 'users/update'
user.rb
class User < ActiveRecord::Base
before_create :add_unsubscribe_hash, :add_true_to_users_table
validates :email, :uniqueness => true
validates_presence_of :email
validates_format_of :email, :with => /\A[-a-z0-9_+\.]+\#([-a-z0-9]+\.)+[a-z0-9]{2,4}\z/i
private
def add_unsubscribe_hash
self.unsubscribe_hash = SecureRandom.hex
end
def add_true_to_users_table
self.subscription = true
end
end
unsubscribe link in the email which calls unsubscribe action
# app/views/job_notifier/send_post_email.html.erb
...
<%= link_to "Unsubscribe", unsubscribe_url(id: #unsubscribe) %>.
diagrammatic view of the error
Its seems that I am missing something, do I need to define something in my users_controller? I have never in my life being able to solve NoMethodError or I don't understand what it's all about.

Answer 1

You get that error because #user (set in UsersController#unsubscribe) is nil. That is what the "for nil:NilClass" in undefined methodunsubscribe_hash' for nil:NilClass` is referring to.
This method doesn't seem correct:
def unsubscribe
user = User.find_by_unsubscribe_hash(params[:unsubscribe_hash])
#user = User.find_by_unsubscribe_hash(user)
end
You are looking up a user by unsubscribe_hash and assigning it to user, and then looking up user by unsubscribe_hash again but passing in user as the value to find_by_unsubscribe_hash.
I believe something like this is more as intended:
def unsubscribe
#user = User.find_by_unsubscribe_hash(params[:unsubscribe_hash])
end

Answer 2

Whenever you see any error messages in ruby of the format:
undefined method 'method_name' for nil:NilClass
you are being told you are trying to call something on a nil object and so the focus of your attention should be on why is that object nil. You are also told in your log where the error occurs - in your case it refers to the line, which refers to #user in #user.unsubscribe_hash in your form declaration.
So #user is nil and in this case it's nil because your controller responsible for rendering the form isn't setting #user:
user = User.find_by_unsubscribe_hash(params[:unsubscribe_hash])
#user = User.find_by_unsubscribe_hash(user)
Now quite why you are attempting to find the user and then pass that user into the second line to find #user is beyond me, but anyway the real issue is that you have no user that matches params[:unsubscribe_hash]
So the issue is related to whatever is invoking your unsubscribe action ... you have neglected to add that to your question so I cannot help with that but that is where your focus start.