Decide how Twig filters should process against an array of render arrays

So this would require changing \Drupal\Core\Template\TwigExtension::addClass() and friends.

IMHO Twig Filters do not make sense to apply to an array of render arrays. The problem grows more complex too: what about an array of arrays of render arrays (i.e. with an extra level of indirection)? What about an array that contains both render arrays directly and indirectly?

The better solutions IMHO, because they would be more reliable:

1. — captured as in 📌 [SPIKE] Comprehensive plan for integrating with SDC Active
2. restricting what the accepted contents are of a slot — captured as in 📌 [SPIKE] Comprehensive plan for integrating with SDC Active . ← Applied to this issue, that would mean that a slot only accepts a render element (i.e. ['#type' => …, … => …]) render array, not an arbitrary render array. That'd then allow using the add_class Twig filter without changing it.

Hi,

we have overridden Core's |add_class() and set_attribute() filters in UI Patterns (1 & 2) since May 2023, and... it works.

https://git.drupalcode.org/project/ui_patterns/-/blob/2.0.x/src/Template...

what about an array of arrays of render arrays?

As long as the array is a list, as expected.

It is a simple and useful solution, used by many projects for many months. No need to introduce complicated concepts like "repeatable slots" or "slots restrictions"

Yeah we need something like this.

Especially with SDCs it's becoming common for me to use set_attribute to the next level below.

So for example this works to set the slot attribute if link is a single value.

button: field_link|set_attribute('slot', 'button__link'),

However if link is multivalue, none of the links get the attribute.

In the parent issue it was suggested to do this:

{% for index,item in my_list_of_renderable_arrays %}
  {{ item|add_class('item', 'item--' ~ index) }}
{% endfor %}

but are you excepted to rebuild that as an array? I'd expect it to set the attribute for everything in the list.

I feel like when it's a multi value field it should always apply to all items.

Hi @nicxvan, you have open a MR, can you assign the issue to you so people will know you are working on it?

MR has the code for setattribute, need to do that for add_class too I guess?

I've pushed up the class override, I'm not actively working on this at the moment so no need to assign myself.

This needs tests.