Symfony2 Variable "name" does not exist - php

Question

I'm new to Symfony, so this is most certain a simple mistake from my side.
I get the following error: Variable "worker" does not exist.
The template looks like this:
{% extends "NTSBSServiceBundle::layout.html.twig" %}
{% block body %}
<h1>Rapportera</h1>
{% for worker in workers if workers %}
{{ worker.name }}
{% else %}
<em>Det finns inga öppna protokoll för närvarande...</em>
{% endfor %}
{% endblock %}
And the controller method look like this:
/**
* List all open protocols, grouped by worker.
*
* #Route("/", name="report")
* #Method("GET")
* #Template()
*/
public function indexAction()
{
$em = $this->getDoctrine()->getManager();
$workers = $em->getRepository('NTSBSServiceBundle:Worker')->findAll();
return array(
'workers' => $workers,
);
}
I have checked, and $workers does contain entities from the database. The twig gets rendered. If I remove the for-loop, naturally the error message disappears.
Hoping that someone can explain to me what I'm doing wrong.
UPDATE:
Have confirmed that the correct controller is used by exiting in indexAction(). If i do a print_r of $workers, I get the following output:
Array
(
[0] => NT\SBSServiceBundle\Entity\Worker Object
(
[id:NT\SBSServiceBundle\Entity\Worker:private] => 2
[name:protected] => Worker 1
[mail:protected] => worker1#example.com
[phone:protected] => 123456789
)
[1] => NT\SBSServiceBundle\Entity\Worker Object
(
[id:NT\SBSServiceBundle\Entity\Worker:private] => 3
[name:protected] => Worker 2
[mail:protected] => worker2#example.com
[phone:protected] => 123456789
)
)
Also I have tried to change the rendering-method by changing from annotation to using the render-method, as such:
return $this->render('NTSBSServiceBundle:Report:index.html.twig',array( 'workers' => $workers ));

Answer 1

You can not do {% for i in x if x %}
You have to do
{% if x | length > 0 %}
{% for i in x %}
instructions
{% endfor %}
{% endif %}
Use twig doc : http://twig.sensiolabs.org/doc

Answer 2

I do always loop through arrays in Twig like that:
{% for b in books %}
{{ b.name }}
{% endfor %}
{% if not books %}
<i>{% trans %}utils.nothing{% endtrans %}</i>
{% endif %}
But your error looks like a variable is missing. What is your error message?
Symfony2 Variable “name” does not exist
or
Variable "worker" does not exist.