models/SignupForm.php
public function signup()
    {
        if ($this->validate()) {
            $user = new User();
            $user->username = $this->username;
            $user->email = $this->email;
            $user->setPassword($this->password);
            $user->generateAuthKey();
            if ($user->save()) {
                return $user;
            }
        }

        return null;
    }
public function signup()
    {
        if ($this->validate()) {
            $user = new User();
            $user->username = $this->username;
            $user->email = $this->email;
            $user->setPassword($this->password);
            $user->generateAuthKey();
            if ($user->save()) {
                return $user;
            }
        }

        return null;
    }
Signs user up.

@return User|null the saved model or null if saving fails