Pass custom data to Form Theme in Symfony/Twig - symfony

Question

I'm new to Symfony, currently working with 4.4, and am trying to implement a simple form theme for one specific form, i.e. the theme is in the same file as the form's html.twig file. I have my own form_row block and I'm trying to pass in custom data (an icon to use within the div) when calling it, so something like (this is highly summarised!):
{{ form_row(signUpForm.email, {
attr: { placeholder: 'e.g. bobsmith#gmail.com' },
icon: 'envelope'
}) }}
then try to render in the form as
{%- block form_row -%}
<div>
{{ form_label(form) }}
{{ form_widget(form, {attr: class: 'input'}) }}
<i class="icon {{ icon }}"></i>
</div>
I tried also passing icon via the formBuilder, along the lines of
$builder
->add('email', EmailType::class, [
'attr'=> ['icon' => 'envelope']
])
but no joy. Surely this must be possible! Any assistance would be much appreciated. Thanks

Answer 1

I'm not sure but you can access to your form variable with {{form}} in your theme. So you can use it.
Hope this help
Edit:
You can add property in your entity and use it in template like this :
{%- block form_row -%}
<div>
{{ form_label(form) }}
{{ form_widget(form, {attr: class: 'input'}) }}
{% set myData = form.vars.value %}
<i class="icon {% if myData.type == 'mail' %}envelope{% endif %}"></i>
I think you have a better way to do this but i do something like that and it's work.

Answer 2

So, I managed to find the "proper" way to do what I want: a Form Type Extension. The Symfony Casts tutorial on it is pretty good. In short, you create a class to extend your main form input class; in my case I was dealing with a text based input, so I created an App\Form\ypeExtension\TextIconExtension class, extended from FormTypeExtensionInterface, then implemented configureOptions and buildView (I removed the functions in the interface I didn't fill in):
class TextIconExtension implements FormTypeExtensionInterface
{
public function buildView(FormView $view, FormInterface $form, array $options)
{
$view->vars['icon'] = $options['icon'];
}
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults([
'icon' => 'user'
]);
}
public function getExtendedType()
{
return TextType::class;
}
public function getExtendedTypes(): iterable
{
return [TextType::class];
}
}
Then, in my form template, I can simply pass a value for icon:
{{ form_row(signUpForm.email, {
attr: { placeholder: 'e.g. bobsmith#gmail.com' },
icon: 'envelope'
}) }}