Symfony2.8错误在不使用doctrine的对象上下文中时使用$ this

I am tryin to call a function from my controller and return the $todolist to my controller. But i get this error, when i leave this function inside the controller it works fine, but i don't want it to be in the controller.

This is my controller

namespace AppBundle\Controller;

use Sensio\Bundle\FrameworkExtraBundle\Configurationoute;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;

use AppBundle\Entity\Todo;
use AppBundle\Model\TodoModel;

class TodoController extends Controller
{
    /**
    * @Route("/", name="homepage")
    */
    public function ShowList()
    {
        $todolist = TodoModel::getTodolist();

        $html = $this->container->get('templating')->render(
            'todolist/todolist.html.twig',
            array('todolist' => $todolist)
        );

        return new response($html);
    }
}

This is my model

namespace AppBundle\Model;

use AppBundle\Entity\Todo;

class TodoModel 
{

     public function getTodolist()
     {
       $repository = $this->getDoctrine()
           ->getRepository('AppBundle:Todo');
       $todolist = $repository->findAll();
       return $todolist;
    }

}

Right way to do it is:

public function ShowList()
{
    $entityManager = $this->get('doctrine.orm.entity_manager');
    $repository = $entityManager->getRepository(Todo::class);
    $todolist = $repository->findAll();

    $html = $this->container->get('templating')->render(
        'todolist/todolist.html.twig',
        array('todolist' => $todolist)
    );

    return new Response($html);
}

If you want to do some kind of abstraction with "TODO provider", then better naming for it is TodoProvider instead of TodoModel.

And it should look like:

namespace AppBundle\Todo;

use Doctrine\ORM\EntityManager;
use AppBundle\Entity\Todo;

class TodoProvider
{
    /**
     * @var EntityManager
     */
    private $entityManager;

    /**
     * TodoProvider constructor.
     * @param EntityManager $entityManager
     */
    public function __construct(EntityManager $entityManager)
    {
        $this->entityManager = $entityManager;
    }

    /**
     * @return Todo[]
     */
    public function getAllTodos()
    {
        return $this->entityManager->getRepository(Todo::class)->findAll();
    }
}

Then register TodoProvider as service (http://symfony.com/doc/current/service_container.html) and get in controller with $this->get('my_todo_provider')

You need to inject doctrine into model, and define model as service. And better to use repository.

Using repositories