Combine columns in choice list Symfony form

In my Symfony form I have a choiceType field listing categories. My categorie table looks like this:

id code categorie
1  100  First categorie
2  200  Second categorie
3  210  Second subcategorie

In my form I have a selectfield and with 'choice_label' I can decide which column, either 'code' or 'categorie' to use for the select list. I would like to use both so the user has a selectlist showing:

• 100 First categorie
• 200 Second categorie
• .. etc

Is it possible to join the 2 columns for the choice_label; Concatenate the 2 columns in a string just for the purpose of the selectoptions to show? I have tried to find it here and elsewhere. The official docs do not mention this option.

Even in ChoiceType for choice_label you can use callable to set it link

'choice_label' => function($category, $key, $index) {
    /** @var Category $category */
    return $category->getId() . ' ' . $category->getName();
},

But why do you use ChoiceType for you categories, how do you going to set choices? Why don't you use EntityType?

->add('category', EntityType::class, array(
    'choice_label' => function ($category) {
        return $category->getId() . ' ' . $category->getName();
    },
    'class' => 'AppBundle:Category',
    'query_builder' => function (EntityRepository $er) {
        return $er->createQueryBuilder('c')
            ->orderBy('c.id', 'ASC');
    },
))