Rails 4.1 tests return undefined method `authenticate' for nil:NilClass

Question

I'm working through the treehouse tutorials using Ruby 2.1.2 and Rails 4.1.5 and I got into an issue with my tests in the auth tutorial.

The tutorial says that this code should pass:

def create
    user = User.find(params[:email])
    if user && user.authenticate(params[:password])
        session[:user_id] = user.id
        redirect_to todo_lists_path
    else
        flash.now[:error] = "There was an error logging in. Please check your email and password"
        render action: 'new'
    end
end

Here are my tests:

describe "POST 'create'" do
    context "with correct credentials" do
        let!(:user){
            User.create(
            first_name: "Jason", 
            last_name: "Seifer", 
            email: "jason@teamtreehouse.com", 
            password: "teamtreehouse1234",
            password_confirmation:"teamtreehouse1234")}

          it "redirects to the todo list path" do
            post :create, email: "jason@teamtreehouse.com", password: "treehouse1234"
            expect(response).to be_redirect
            expect(response).to redirect_to(todo_lists_path)
          end

          it "finds the user" do
            expect(User).to receive(:find_by).with({email: "jason@teamtreehouse.com"}).and_return(user)
            post :create, email: "jason@teamtreehouse.com", password: "treehouse1234"
          end

          it "authenticates the user" do
            User.stub(:find_by).and_return(user)
            expect(user).to receive(:authenticate)
            post :create, email: "jason@teamtreehouse.com", password: "treehouse1234"
         end

          it "sets the user id in the session" do
            post :create, email: "jason@teamtreehouse.com", password: "treehouse1234"
            expect(session[:user_id]).to eq(user.id)
          end

          it "sets the flash success messagge" do
            post :create, email: "jason@teamtreehouse.com", password: "treehouse1234"
            expect(flash[:success]).to eq("Thanks for logging in!")
          end
        end

        context "with blank credentials" do
          it "renders the new template" do
            post :create
            expect(response).to render_template('new')
          end
          it "sets the flash error messagge" do
            post :create, email: "jason@teamtreehouse.com", password: "treehouse1234"
            expect(flash[:error]).to eq("There was an error logging in. Please check your email and password")
          end
        end

        context "with incorrect credentials" do
          let!(:user){
            User.create(
            first_name: "Jason", 
            last_name: "Seifer", 
            email: "jason@teamtreehouse.com", 
            password: "teamtreehouse1234",
            password_confirmation:"teamtreehouse1234")}

          it "renders the new template" do
            post :create, email: user.email, password: "fuckingpassword"
            expect(response).to render_template('new')
          end
          it "sets the flash error messagge" do
            post :create, email: user.email, password: "fuckingpassword"
            expect(flash[:error]).to eq("There was an error logging in. Please check your email and password")
          end
        end

      end

That gives me the error undefined method `authenticate' for nil:NilClassthe only way I've made the tests pass is with the following:

class UserSessionsController < ApplicationController
    def new
    end

    def create
        user = User.find_by(email: params[:email])

        if user.nil?
            flash[:error] = "There was an error logging in. Please check your email and password"
            render action: 'new'
        else
            user.authenticate(params[:password])
            session[:user_id] = user.id
            flash[:success] = "Thanks for logging in!"
            redirect_to todo_lists_path
        end 
    end
end

I know it's ugly but it worked, right to the point that I needed to test whether it denied authentication with the right user but the wrong password. The tests returned two errors:

1) UserSessionsController POST 'create' with incorrect credentials renders the new template
Failure/Error: expect(response).to render_template('new')

expecting <"new"> but rendering with <[]>

2) UserSessionsController POST 'create' with incorrect credentials sets the flash error messagge 
Failure/Error: expect(flash[:error]).to eq("There was an error logging in. Please check your email and password")
expected: "There was an error logging in. Please check your email and password"
    got: nil

The first example failed because for what ever reason(maybe rspec) the if clause doesn't handle user.authenticate(params[:password]) because it returns a hash.

let it be noted that the following code works in bin/rails console :

> user = User.create(first_name:"John", last_name: "Doe", email: "jon.doe@me.com", password: "password", password_confirmation: "password")
> user.save
> if user && user.authenticate("password")
> puts "wawa"
> end
wawa
=> nil

I've tried refactoring the create method so that it authenticates on assignment to no avail:

def create user = User.find_by(email: params[:email]).authenticate(params[:password])

if user.nil? || user == false
    flash[:error] = "There was an error logging in. Please check your email and password"
    render action: 'new'
else
    session[:user_id] = user.id
    flash[:success] = "Thanks for logging in!"
    redirect_to todo_lists_path
end

end

I get undefined method `authenticate' for nil:NilClass again.

Answer 1 · 2014-09-10T19:02:35Z

September 10, 2014 7:02pm

Found the bug it wasn't in the logic it was in the tests, I was testing the password with incorrect credentials treehouse123 instead of the one that was being created in my user teamtreehouse123.

Inspiration came in this debugging code:

    def create
      user = User.find_by(email: params[:email])
      if (user.nil? == false) 
        if user.authenticate(params[:password]) 
          puts user.authenticate(params[:password])
          puts "NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN Batman!"
          session[:user_id] = user.id
          flash[:success] = "Thanks for logging in!"
          redirect_to todo_lists_path
        else 
          puts user.authenticate(params[:password])
          puts "waka waka waka waka waka waka waka waka waka waka waka waka waka waka waka waka"
          flash[:error] = "There was an error logging in. Please check your email and password"
          render action: "new"
        end
      else
        flash[:error] = "There was an error logging in. Please check your email and password"
        render action: "new"
      end
    end

user.authenticate(params[:password]) always returned false, regardless of what I did, as Jason said once spelling always gets us. Thanks Aurelien and Kang Kyu!

The Treehouse code is correct, but I'm changing all occurrences of teamtreehouse123 to password.

Answer 2 · 2014-09-09T10:59:32Z

September 9, 2014 10:59am

Hello Ricardo, I didn't figure this out, but from the test code I suspect let declaration didn't do its job. Well sorry couldn't be much help

Answer 3 · 2014-09-09T08:00:16Z

September 9, 2014 8:00am

1) Try replacing render 'new' with render "new" (double quotes), and see if that fixes your first problem.

You can also do render :new. Symbols are strings but can behave as representation of a name that Ruby saves during the execution of the program. Symbols are really handy in many ways when working with rails.

(see here different examples of rendering views/templates: http://guides.rubyonrails.org/layouts_and_rendering.html)

2) In your User model did you add the Public Instance Method has_secure_password?

class User < ActiveRecord::Base
  has_secure_password
end

has_secure_password will provide a series of methods including the method authenticate

user = User.new(name: 'david', password: '', password_confirmation: 'nomatch')
user.save                                                       # => false, password required
user.password = 'mUc3m00RsqyRe'
user.save                                                       # => false, confirmation doesn't match
user.password_confirmation = 'mUc3m00RsqyRe'
user.save                                                       # => true
user.authenticate('notright')                                   # => false
user.authenticate('mUc3m00RsqyRe')                              # => user
User.find_by(name: 'david').try(:authenticate, 'notright')      # => false
User.find_by(name: 'david').try(:authenticate, 'mUc3m00RsqyRe') # => user
``

Answer 4 · 2014-09-09T10:23:58Z

September 9, 2014 10:23am

I will also add this answer. Sorry about clogging up your question.

Treehouse made a mistake in their video page with their code snippet.

They wrote

user = User.find(params[:email])

When you write ModelName.find() it expects to look for an id number. An exception to that Rails rule would be to create a custom to_params method in the model where you can have the model search by another column instead of ID.

However Ruby provides other methods when you want to find a record by using another column instead of the ID column such as

ModelName.find_by(column_name: [params: column_name])

# And you can also remove the parentheses because Ruby is cool

ModelName.find_by column_name: [params: column_name]

# OR you can use the where method

ModelName.where(column_name: [params: column_name]) 

#and this gets handy if you chain it with .first_or_create when creating Tag words for example

I hope this helps clears up the confusion about the find_by() error.

Jason actually uses find_by(email: params[:email]) in the video not like in the code snippet on the presentation page.

The second problem with your refactored code is actually really simple:

    def create
        user = User.find_by(email: params[:email])

        if user.nil?
            flash[:error] = "There was an error logging in. Please check your email and password"
            render action: 'new'
        else
            user.authenticate(params[:password])
            session[:user_id] = user.id
            flash[:success] = "Thanks for logging in!"
            redirect_to todo_lists_path
        end 
    end

In the code above you first check if the user with email exists, if it doesnt it throws an error. If it does exist it will try to authenticate the user with the given password. If the password is good it will work, however you did not add a conditional if the authentication fails with the wrong password. Thats why your test gives you the error undefined method `authenticate' for nil:NilClass (Jason actually explains that part in the first of the two videos) . When you refactored your own code the second time, the problem remained

Now in the snippet code on the presentation and in Jason's video, he uses conditional block with && operator. This will check if the user exists in the database with the given email AND if the user has authenticated . You can correct your code by trying out

def create
    user = User.find_by(email: params[:email])
    if user.nil?
       flash[:error] = "There was an error logging in. Please check your email and password"
       render action: 'new'
   else
      if user.authenticate(params[:password])
          session[:user_id] = user.id
          flash[:success] = "Thanks for logging in!"
          redirect_to todo_lists_path
      else
          flash[:error] = "There was an error logging in. Please check your email and password"
          render action: 'new'
      end
   end
end

But that is the same as

def create
    user = User.find_by(email: params[:email])
    if user && user.authenticate(params[:password])
        session[:user_id] = user.id
          flash[:success] = "Thanks for logging in!"
          redirect_to todo_lists_path

   else
      flash[:error] = "There was an error logging in. Please check your email and password"
       render action: 'new'
   end
end

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Ricardo Acuna

Ricardo Acuna

Rails 4.1 tests return undefined method `authenticate' for nil:NilClass

4 Answers

Ricardo Acuna

Ricardo Acuna

Aurelien Schlumberger

Aurelien Schlumberger

Kevin Mulhern

Kevin Mulhern

Kang-Kyu Lee

Kang-Kyu Lee

Kang-Kyu Lee

Kang-Kyu Lee

Ricardo Acuna

Ricardo Acuna

Aurelien Schlumberger

Aurelien Schlumberger

Aurelien Schlumberger

Aurelien Schlumberger

Ricardo Acuna

Ricardo Acuna

Aurelien Schlumberger

Aurelien Schlumberger

Ricardo Acuna

Ricardo Acuna

Aurelien Schlumberger

Aurelien Schlumberger

Aurelien Schlumberger

Aurelien Schlumberger

Ricardo Acuna

Ricardo Acuna

Aurelien Schlumberger

Aurelien Schlumberger

Ricardo Acuna

Ricardo Acuna

Aurelien Schlumberger

Aurelien Schlumberger

Ricardo Acuna

Ricardo Acuna

Aurelien Schlumberger

Aurelien Schlumberger

Ricardo Acuna

Ricardo Acuna