Entity

<?php

namespace My\HelloBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Security\Core\User\UserInterface;

/**
 * My\HelloBundle\Entity\User
 *
 * @ORM\Table()
 * @ORM\Entity
 */
class User implements UserInterface
{
    /**
     * @var integer $id
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var string $username
     *
     * @ORM\Column(name="username", type="string", length=128)
     */
    private $username;

    /**
     * @var string $password
     *
     * @ORM\Column(name="password", type="string", length=128)
     */
    private $password;

    /**
     * @var string $first_name
     *
     * @ORM\Column(name="first_name", type="string", length=128)
     */
    private $first_name;

    /**
     * @var string $last_name
     *
     * @ORM\Column(name="last_name", type="string", length=128)
     */
    private $last_name;

    /**
     * @var string $email
     *
     * @ORM\Column(name="email", type="string", length=128)
     */
    private $email;

    /**
     * @var smallint $role
     *
     * @ORM\Column(name="role", type="string", length=128)
     */
    private $role;

    public function __construct()
    {
        $this->isActive = true;
        $this->salt = base_convert(sha1(uniqid(mt_rand(), true)), 16, 36);
    }



    /**
     * Get id
     *
     * @return integer
     */
    public function getId()
    {
        return $this->id;
    }
    function save($obj){
        $em = $obj->getDoctrine()->getEntityManager();
        $em->persist($this);
        $em->flush();
    }

    function getRoles(){
    }

    function eraseCredentials(){

    }

    function equals(UserInterface $user){
        return ($user->getEmail() === $this->getEmail()) && ($user->getPassword() === $this->getPassword());
    }


    /**
     * Set last_name
     *
     * @param string $lastName
     */
    public function setLastName($lastName)
    {
        $this->last_name = $lastName;
    }

    /**
     * Get last_name
     *
     * @return string
     */
    public function getLastName()
    {
        return $this->last_name;
    }

    /**
     * Set email
     *
     * @param string $email
     */
    public function setEmail($email)
    {
        $this->email = $email;
    }

    /**
     * Get email
     *
     * @return string
     */
    public function getEmail()
    {
        return $this->email;
    }

    /**
     * Set password
     *
     * @param string $password
     */
    public function setPassword($password)
    {
        $this->password = $password;
    }

    /**
     * Get password
     *
     * @return string
     */
    public function getPassword()
    {
        return $this->password;
    }

    /**
     * Set role
     *
     * @param smallint $role
     */
    public function setRole($role)
    {
        $this->role = $role;
    }

    /**
     * Get role
     *
     * @return smallint
     */
    public function getRole()
    {
        return $this->role;
    }

    /**
     * Set first_name
     *
     * @param string $firstName
     */
    public function setFirstName($firstName)
    {
        $this->first_name = $firstName;
    }

    /**
     * Get first_name
     *
     * @return string
     */
    public function getFirstName()
    {
        return $this->first_name;
    }

    /**
     * Set username
     *
     * @param string $username
     */
    public function setUsername($username)
    {
        $this->username = $username;
    }
    /**
     * Get username
     *
     * @return string
     */
    public function getUsername()
    {
        return $this->username;
    }
     /**
     * Set salt
     *
     * @param string $salt
     */
    public function setSalt($salt)
    {
        $this->salt = $salt;
    }

    function getSalt()
    {
        return $this->salt;
    }
}