How to work with Versionable entities with Doctrine2 Extensions?

I'm trying to use Versionable extension from Doctrine2Extensions but I couldn't a way to implement it.

It is mentioned that we need to 'implements' Versionable interface (which is empty by the way)

Requirements of your entities are:

Single Identifier Column (String or Integer)

Entity has to be versioned (using @version annotation)

Implementing Versionable would look like:

namespace MyProject;
use DoctrineExte开发者_运维知识库nsions\Versionable\Versionable;

class BlogPost implements Versionable {
    // blog post API 
}

From the documentation.

What I don't understand is :

Single Identifier Column (String or Integer) Entity has to be versioned (using @version annotation)

What those both requirements means?

Here my entity:

<?php
namespace Jo\Model;
use DoctrineExtensions\Versionable\Versionable;
/**
 * @Entity
 */
class Comment implements Versionable
{
    /**
     * @Id
     * @Column(type="integer")
     * @GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @Column(type="string", length=255)
     */
    protected $body;

What are missing to make version works?

Your $id property provides a single identifier.

From my reading of things, you'll also need a $version (or similar) property, which could be an integer or datetime, and it must be annoted with @Version

This (old) blog post may help give you some more insight (but some of it may be out of date)