[4.x]:{% namespace %} Twig tag should allow 0

[engram-design]

What happened?

Thinking that the {% namespace %} tag should accept 0 as a value, and it currently doesn't. Probably to do with a falsey check, but I can't figure out how that works, sorry!

{% set items = ['first', 'second'] %}

{% for item in items %}
    {% namespace loop.index0 %}
        {{ tag('input', {
            name: item,
        }) }}
    {% endnamespace %}
{% endfor %}

// Produces
<input name="first">
<input name="1[second]">

// Expected
<input name="0[first]">
<input name="1[second]">

In reality, this would be surrounded by fields and the field handle, but in this reduced example, you can't have multiple {% namespace %} tags, so in a real-world use-case you'd produce:

// Expected
<input name="fields[myField][0][first]">
<input name="fields[myField][1][second]">

My use-case here is that the value for a field is an array, and I'd like to keep things simple by using an array syntax, rather than new1 or similar like Matrix does.

Craft CMS version

4.5.9

PHP version

No response

Operating system and version

No response

Database type and version

No response

Image driver and version

No response

Installed plugins and versions

[engram-design]

Oh, managed to track down where that is, keen to hear your opinion on #13944

[brandonkelly]

Namespaces are used to prefix id HTML attributes, and id attributes aren’t allowed to begin with a number. So namespaces shouldn’t be either.

I’ve just added a check to ensure namespaces follow id attribute rules for Craft 5 (d568986).

You can work around that by prefixing your keys with a string, e.g. value:0, value:1, etc.

[brandonkelly]

Nevermind, that turned out to be pretty heavy-handed, and I forgot that we’re already ensuring namespaces are properly formatted for id attributes via craft\helpers\Html::id().

Your PR is now merged for the next Craft 4 release, and I’ve adjusted Html::id() to trim out any leading digits for Craft 5. (Entirely-numeric IDs will end up getting normalized to a 10-digit random string.)

[engram-design]

Cheers! I know it's kinda a "dumb" PR, but might be handy in some instances...

[brandonkelly]

4.5.13 is out with that change!