Trying to complete exercise 1, Chapter 8, section 8.5 - ruby-on-rails

Question

This is my first post here so hopefully I have followed the guide but if there is a better way to post, feel free to point me in the right direction - I learn fast.
I am new to rails and working through the Hartl Rails Tutorial. I searched google and here for the solution but can't seem to locate an answer to why the tests fail on click_button "Sign in".
I also went through the rails casts video Railscasts #270 Authentication
What am I missing so I can get these tests to pass? Any help would be greatly appreciated.
All the test pass if i use the form_for but fail when I use form_tag in .sessions/new.html.erb. The Sign_in page still renders correctly but once I try to sign in, the web page shows an error on:
def create
user = User.find_by(email: params[:session][:email].downcase)
Here is the exercise that I am trying to accomplish - Chapter 8, section 8.5, exercise 1:
8.5 Exercises
Refactor the signin form to use form_tag in place of form_for. Make
sure the test suite still passes. Hint: See the RailsCast on
authentication in Rails 3.1, and note in particular the change in
the structure of the params hash.
.sessions/new.html.erb
<% provide(:title, "Sign in") %>
<h1>Sign in</h1>
<div class="row">
<div class="span6 offset3">
<%= form_tag sessions_path do %>
<%= label_tag :email %>
<%= text_field :email, params[:email] %>
<%= label_tag :password %>
<%= password_field_tag :password %>
<%= submit_tag "Sign in", class: "btn btn-large btn-primary" %>
<% end %>
<!--
<%= form_for(:session, url: sessions_path) do |f| %>
<%= f.label :email %>
<%= f.text_field :email %>
<%= f.label :password %>
<%= f.password_field :password %>
<%= f.submit "Sign in", class: "btn btn-large btn-primary" %>
<% end %>
-->
<p>New user? <%= link_to "Sign up now!", signup_path %></p>
</div>
</div>
This is the output of rspec spec/
> Failures:
1) Authentication signin with invalid information
Failure/Error: before { click_button "Sign in" }
NoMethodError:
undefined method `[]' for nil:NilClass
# ./app/controllers/sessions_controller.rb:7:in `create'
# ./spec/requests/authentication_pages_spec.rb:19:in `block (4 levels) in <top (required)>'
2) Authentication signin with invalid information
Failure/Error: before { click_button "Sign in" }
NoMethodError:
undefined method `[]' for nil:NilClass
# ./app/controllers/sessions_controller.rb:7:in `create'
# ./spec/requests/authentication_pages_spec.rb:19:in `block (4 levels) in <top (required)>'
3) Authentication signin with invalid information after visiting another page
Failure/Error: before { click_button "Sign in" }
NoMethodError:
undefined method `[]' for nil:NilClass
# ./app/controllers/sessions_controller.rb:7:in `create'
# ./spec/requests/authentication_pages_spec.rb:19:in `block (4 levels) in <top (required)>'
4) Authentication signin with valid information
Failure/Error: fill_in "Email", with: user.email.upcase
Capybara::ElementNotFound:
Unable to find field "Email"
# ./spec/requests/authentication_pages_spec.rb:41:in `block (4 levels) in <top (required)>'
5) Authentication signin with valid information
Failure/Error: fill_in "Email", with: user.email.upcase
Capybara::ElementNotFound:
Unable to find field "Email"
# ./spec/requests/authentication_pages_spec.rb:41:in `block (4 levels) in <top (required)>'
6) Authentication signin with valid information
Failure/Error: fill_in "Email", with: user.email.upcase
Capybara::ElementNotFound:
Unable to find field "Email"
# ./spec/requests/authentication_pages_spec.rb:41:in `block (4 levels) in <top (required)>'
7) Authentication signin with valid information
Failure/Error: fill_in "Email", with: user.email.upcase
Capybara::ElementNotFound:
Unable to find field "Email"
# ./spec/requests/authentication_pages_spec.rb:41:in `block (4 levels) in <top (required)>'
8) Authentication signin with valid information followed by signout
Failure/Error: fill_in "Email", with: user.email.upcase
Capybara::ElementNotFound:
Unable to find field "Email"
# ./spec/requests/authentication_pages_spec.rb:41:in `block (4 levels) in <top (required)>'
.....
./spec/requests/authentication_pages_spec.rb
require 'spec_helper'
describe "Authentication" do
subject { page }
describe "signin page" do
before { visit signin_path }
it { should have_content('Sign in') }
it { should have_title('Sign in') }
end
#Testing for sign in failure
describe "signin" do
before { visit signin_path }
describe "with invalid information" do
before { click_button "Sign in" }
it { should have_title('Sign in') }
# This uses Capabara have_selector method
# dot means "class" in CSS testing for div tag with classes "alert"
# and "alert-error" and the error message contains "invalid"
it { should have_selector('div.alert.alert-error', text: 'Invalid') }
describe "after visiting another page" do
before { click_link "Home" }
it { should_not have_selector('div.alert.alert-error') }
end
end
# Testing for sign success
describe "with valid information" do
# This is using FactoryGirl gem
let(:user) { FactoryGirl.create(:user) }
before do
fill_in "Email", with: user.email.upcase
fill_in "Password", with: user.password
click_button "Sign in"
end
# Uses Capybara's have_link method - takes arguments as text
# of the link and optional :href
it { should have_title(user.name) }
it { should have_link('Profile', href: user_path(user)) }
it { should have_link('Sign out', href: signout_path) }
it { should_not have_link('Sign in', href: signin_path) }
describe "followed by signout" do
before { click_link "Sign out" }
it { should have_link('Sign in') }
end
end
end
end
./app/controllers/sessions_controller.rb
class SessionsController < ApplicationController
def new
end
def create
user = User.find_by(email: params[:session][:email].downcase)
if user && user.authenticate(params[:session][:password])
# Sign the user in and redirect to the user's show page.
sign_in user
redirect_to user
else
# Flash [:error] comes from bootstap CSS
flash.now[:error] = 'Invalid email/password combination'
# This line activates the link signin to show the page view new.html.erb
render 'new'
end
end
def destroy
sign_out
redirect_to root_url
end
end

Answer 1

this works for me
new.html.erb
<% provide(:title, "Sign in") %>
<h1>Sign in</h1>
<div class="row">
<div class="span6 offset3">
<%= form_tag sessions_path do %>
<%= label_tag :email %>
<%= text_field_tag :email %>
<%= label_tag :password %>
<%= password_field_tag :password %>
<%= submit_tag "Sign in", class: "btn btn-large btn-primary" %>
<% end %>
<p>New user? <%= link_to "Sign up now!", signup_path %></p>
</div>
</div>
sessions_controller.erb
class SessionsController < ApplicationController
def new
end
def create
user = User.find_by(email: params[:email].downcase)
if user && user.authenticate(params[:password])
sign_in user
redirect_to user
else
flash.now[:error] = 'Invalid email/password combination'
render 'new'
end
end
def destroy
sign_out
redirect_to root_url
end
end
Please tell me if it works for you.
Thanks

Answer 2

In the exercise is mentioned that the structure of the params hash is changed. You need to edit this in the controller like following (this works in my case). It does not work currently because the params aren't accessible.
User.find_by_email(params[:email].downcase) and authenticate(params[:password]) are modified. If somebody can elaborate why this is feel free to do so.
An extract of my code you can find here:
def create
user = User.find_by_email(params[:email].downcase)
if user && user.authenticate(params[:password])
# Sign in the user and redirect to user show page
sign_in user
redirect_to user
else
flash.now[:error] = 'Invalid email/password combination'
render 'new'
end
end