rails tutorial Chapter 9

Introduction

I will post the process of advancing the rails tutorial on my own.

It touches on words that I didn't understand in the process, jammed errors, and so on.

Please point out any mistakes as it is an output of personal learning.

Since this is my first post, I think there are many places that are difficult to read, but please forgive me.

Chapter 9 Evolving Login Mechanism

9.1.1 Memory token and encryption

Review of attr_accessor

reference https://qiita.com/Hassan/items/0e034a1d42b2335936e6 .remember_token can be used (remember_token attribute can be used)

def remember
  self.remember_token = User.new_token
  update_attribute(:remember_digest, User.digest(remember_token))
end

The last (remember_token) omits self.

9.1.2 Keeping logged in

BCrypt::Password.new(remember_digest) == remember_token

If you take a closer look at this code, it looks really strange. The bcrypt-encrypted password is compared directly to the token. (rails tutorial Quoted from Chapter 9)

Hmmm, surely ...

Is the digest decrypted when comparing with ==? However, the hash of bcrypt should not be decrypted, so it should not be decrypted. (rails tutorial Quoted from Chapter 9)

Well, what's going on?

BCrypt::Password.new(remember_digest).is_password?(remember_token)

Apparently the two codes above have the same meaning. Also, it seems that the is_password? method validates the object and the arguments passed to it and returns true if they match.

9.3.2 Test [Remember me]

Also, the log_in_as helper method defined in Listing 9.24 defines it as session [: user_id]. At this rate, it is very difficult to check the complicated branching process of the current_user method with an integration test. (rails tutorial Quoted from Chapter 9)

Hmm? Why? A. Because the session method cannot be handled in the integration test

test/test_helper.rb

def log_in_as(user)
    session[:user_id] = user.id #Not available
end

test/helpers/sessions_helper_test.rb

test "current_user returns right user when session is nil" do
    assert_equal @user, current_user
    assert is_logged_in?
end

What is this current_user? It seems that it becomes a model object after the current_user method is executed. Perhaps,,,

In other words log_in user And so on, and I think the session method is also being executed ...

app/helpers/sessions_helper.rb

def current_user
  if user_id = session[:user_id] #false
    @current_user ||= User.find_by(id: user_id)
  elsif user_id = cookies.signed[:user_id] #true
    user = User.find_by(id: user_id)
    if user && user.authenticated?(cookies[:remember_token])
      log_in user #Log in
      @current_user = user
    end
  end
end

The current_user method is a model object that returns an instance of the model as a return value.

test/helpers/sessions_helper_test.rb

test "current_user returns nil when remember digest is wrong" do
    @user.update_attribute(:remember_digest,User.digest(User.new_token))
    assert_nil current_user
end

@user.update_attribute(:remember_digest, User.digest(User.new_token))

Updated remember_digest to new one.

assert_nil current_user

Is

app/helpers/sessions_helper.rb

def current_user
  if user_id = session[:user_id]
    @current_user ||= User.find_by(id: user_id)
  elsif user_id = cookies.signed[:user_id]
    user = User.find_by(id: user_id)
    if user && user.authenticated?(cookies[:remember_token]) #false and current_user becomes nil
      log_in user
      @current_user = user
    end
  end
end

if user && user.authenticated?(cookies[:remember_token])

I am checking if current_user is nil in this verification.

At the end

In this chapter, there were few errors and I was able to understand the contents well.