不了解RailsCast教程中的一些代码

Question

I watched the RailCasts tutorial #274 on Remember Me and Reset Password. The code he adds is the following inside user.rb

def send_password_reset
  generate_token(:password_reset_token)
  save!
  UserMailer.password_reset(self).deliver
end

def generate_token(column)
  begin
    self[column] = SecureRandom.urlsafe_base64
  end while User.exists?(column => self[column])
end

Here what I don't understand is why the save! call inside send_password_reset ? Also, I'm not familiar with the syntax in generate_token : self[column]= . Is this the way to set a column inside a database table?

Here's the create action of the password_resets_controller

  def create
    user = User.find_by_email(params[:email])
    user.send_password_reset if user
    redirect_to root_path, notice: "Email sent with password reset instructions."
  end

Answer 1

save! saves the object and raises an exception if it fails.

---

self[column]= , is a slight meta-programming.

Usually, when you know the column name, you'd do: self.password_reset_token= . Which is the same as self[:password_reset_token]= or self["password_reset_token"]= .

So it's easy to abstract it a bit passing column name as string/symbol.

Clearer?

Answer 2

1) save! is like save , but raise a RecordInvalid exception instead of returning false if the record is not valid.

Example from my console:

User.new().save  # => false 
User.new().save! # ActiveRecord::RecordInvalid: Validation failed: Password can't be blank,  Email can't be blank

2) self[column]= there for setting users column.