The morning standup was a quick one and we returned to our desks. My pair made good progress in the morning and we had an hour lunch break from 12:30 until 13:30. From 13:30 until 14:30 we were reviewing our code from the morning and headed down for our standups (we were in different bytes) at 14:30.

The 14:30 standup ended relatively quickly as we had a session focused on heroku as many of us were finding it challenging to upload their bookmark managers on the web, using heroku. After the session, my pair partner and I resumed going through the exercises and ended the day experimenting with our results.

Our major challenge was to understand to logic behind DataMapper’s Validation Confirmation. So our code looked like this:

class User
  include DataMapper::Resource

  property :id, Serial
  property :email, String
  property :password_digest, Text

  attr_reader :password
  attr_accessor :password_confirmation

  validates_confirmation_of :password

  def password=(password)
    @password = password
    self.password_digest = BCrypt::Password.create(password)
  end

end

We were asking the user to fill in a form and submit it. We were then using the information to create a user in our database. The code in our Controller looked like this and the parameteres were provided by the user when they submitted their form earlier:

post '/users' do
  user = User.create(email: params[:email], password: params[:password], password_confirmation: params[:password_confirmation])
  session[:user_id] = user.id
  redirect '/users'
end

As you could see, we were asking the user to provide an email address, password and to confirm that password. If the passwords were not identical, the creation of a new user would fail. However, it took us a long time to get our heads around, how on earth it was doing the comparison between the password and the password_confirmation inputs. The magic happened thanks to validates_confirmation_of in our User class.

What validates_confirmation_of did was it took a parameter, in our case :password, and by default the value it’s looking to compare the parameter in question ( i.e. :password) was #{parameter}_confirmation - i.e password_confirmation. As you can see our user had already given us the password_confirmation information and thanks to the password method, we had also assigned the user’s input of the password to the @password variable which we could read thanks to our attr_reader. What happened next was, the DataMapper did its magic and compared our password and password_confirmation and if they were identical proceeded by generating an encrypted password (2nd line of our password method) and now we had all of our information to create an user in our database (property: id would be generated automatically, however we would have needed values for the property: email and property :password_diggest) which we now had.

Are you still awake? I am not, good night.

Zhivko