Symfony: how to cache a FormInterface object - forms

Question

I have a form type in Symfony that shows in every page list and I'd like to catch it to avoid unnecessary database queries as it uses two EntityTypes fields:
->add('brand', EntityType::class, [
'required' => false,
'class' => Brand::class,
'choice_label' => 'name',
'query_builder' => function (BrandRepository $er) {
return $er->createQueryBuilder('b')
->orderBy('b.name', 'ASC');
},
])
->add('car_manufacturer', EntityType::class, [
'class' => CarManufacturer::class,
'choice_label' => 'name',
'required' => false,
'query_builder' => function (CarManufacturerRepository $er) {
return $er->createQueryBuilder('m')
->orderBy('m.name', 'ASC');
},
])
->add('Search', SubmitType::class);
So in the controller I tried to do this:
private function getFiltersForm(): FormInterface {
$cachedForm = $this->cache
->getItem('form_list_filters')
->expiresAfter(3600*24);
if (!$cachedForm->isHit()) {
$form = $this->formFactory->createNamedBuilder('', SearchItemType::class)->getForm();
$cachedForm->set($form);
$this->cache->save($cachedForm);
}
return $cachedForm->get();
}
But it doesn't work, the isHit()is always false and the form is always regenerated which makes me thing there must be some problem on the save process.
Any idea? thanks in advance