How to fix 'Variable does not exist' when using FormBuilder? - symfony

Question

I've worked through a few of the Forms-Tutorials on the Symfony-Page (especially How to Embed a Collection of Forms, How To use a Form without a Dataclass & CollectionType Field ).
I'm trying to show a form with multiple lead partners which can be edited and submitted back to the system.
But i get a Twig_Runtime_Error saying: ''Variable "lead_partners" does not exist''.
My Twig:
{% block content %}
<div>
{{ form_start(form) }}
{% for partner in lead_partners %}
{{ form_row(partner.name) }}
{% endfor %}
{{ form_end(form) }}
</div>
{% endblock content %}
My Controller Code:
public function overview(Request $request, \App\Utility\LeadPartnerLoader $LeadPartnerLoader)
{
$leadPartnerList = $LeadPartnerLoader->loadAll();
$form = $this->createFormBuilder($leadPartnerList)
->add('lead_partners', CollectionType::class, [
'entry_type' => LeadPartnerFormType::class,
])->getForm();
$form->handleRequest($request);
if($form->isSubmitted() && $form->isValid())
{
$data = $form->getData();
}
return $this->render(
'lead_partner_overview2.html.twig',
[
'form' => $form->createView()
]);
}
And the Form Type (LeadPartnerFormType):
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(array(
'data_class' => LeadPartner::class,
));
}
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('id', HiddenType::class)
->add('name', TextType::class);
}
$leadPartnerList is of type array.
What am i doing wrong/missing here?
Kind Regards

Answer 1

It seems your action overview soesn't return the lead_partners variable you use in your template.
You can try to do this
return $this->render(
'lead_partner_overview2.html.twig',
[
'form' => $form->createView(),
'lead_partners' => $leadPartnerList, // I gess that's the list you want to loop ?
]);