Can't create new object in SQLite using DataMapper

I am new to Ruby and Sinatra world and I am trying to create a database using SQLite3 with Datamapper as ORM. I have installed the gems required for this action. This is how I am doing db and model:

DataMapper.setup(:default, "sqlite3://#{Dir.pwd}/development.db")

class User
  include DataMapper::Resource

  property :id, Serial
  property :email, String, :required => true
  property :first_name, String
  property :last_name, String
  property :password_hash, String
  property :password_salt, String
end

DataMapper.finalize

      

        
        
        
      

    

I have an HTML registration form:

<form action="/signup" method="POST" accept-charset="utf-8">
    <input type="text" name="first_name" placeholder="First Name">
    <input type="text" name="last_name" placeholder="Last Name">
    <input type="mail" name="email" placeholder="Email">
    <input type="password" name="password" placeholder="Password">
    <button type="submit">Register me !</button>
</form>

      

        
        
        
      

    

This is how I handle the registration action:

post "/signup" do

  password_salt = BCrypt::Engine.generate_salt
  password_hash = BCrypt::Engine.hash_secret(params[:password], password_salt)

  User.create(email: params[:email], first_name: params[:first_name], last_name: params[:last_name], password_hash: password_hash, password_salt: password_salt)

  redirect to '/home'

end

      

        
        
        
      

    

When I execute this and after that I register User.all it does not register the users I have registered.

But if I run irb and typed:

The new user remains in the database.

Any ideas why I can't create the users runtime?

PS There are no errors in the console.

PS 2. I found that the password_salt and password_hash variables are the problem. Both are strings, when I pass them to the create function it doesn't work, but if I pass for example a "test" to the function it works fine. When I write these 2 variables down they seem fine too.