FILTER option based on a specific product metafield list

[bacounts]

While testing and researching #1456, I came across the following notation about comma-separated lists for a "filter based on a specific variant metafield".... https://shopify.dev/themes/navigation-search/filtering/storefront-filtering#variant-specific-filters.

While this notation is referring to the URL structure, the notion of filtering from a comma-separated metafield is worth exploring.

It seems counterintuitive not to have a better option that provides similar functionality to "tag groups," which were standard practice before storefront filtering. These tag groups allowed for more intuitive user filtering, especially when a merchant did not want to create a new variable option or all three options were already occupied within a product.

Possible solution:
The "single line of text" metafield allows a select menu option, which could be extended to a multi-select menu. Creating a new collapsible menu for every item like a "material" would be a nightmare and take up the 20 slots custom filtering slots available, especially on a store with a large catalog.

@tyleralsbury is looking into a core filtering issue I raised in #788; maybe this issue could be triaged alongside?!

Proof:
Comunity thread of people discussing this issue: https://community.shopify.com/c/technical-q-a/insert-a-table-in-product-description-area-with-metafields-amp/td-p/1413183 — issue also raised in #381 (comment)

A separated list metafield could come in handy in other places like the product page. By giving access to the storefront API, I could eventually create a block that lists each of these values as a clickable URL, creating a pho "tag list" that allows the buyer to click and return to a filtered collection for that value. << This is a rough example to prove scalability.

I have included some reference images below using my system.

Originally posted by @bacounts in #1456 (comment)
CC: @tyleralsbury @carolineschnapp

[2rvdev]

Hello,
Thank you for mentionning this issue, again.
This issue has been reported numerous time since many months and we still don't have any workaround.
I don't understand why this problem is overlooked by the team.
I sell bikes and most of my bikes can be used in multiple terrain (city, country, moutain, etc...) and I actually don't have a solution to materialize this on my shop.

[carolineschnapp]

Hi @bacounts, @2rvdev, this has been fixed now.

The “Single Line Text” metafields can accept a list of values.

Here is some documentation on that: https://docs.google.com/document/d/1z4w5ETifSwQ90VHBAfTwjtWITkFLpvL80RBYqT0YDSc/edit#heading=h.c85bw4abdn5t

[carolineschnapp]

@melissaperreault this wasn't a theme issue, but a Shopify backend limitation. It's been resolved now. No change needs to be made to themes.

[bacounts]

@carolineschnapp - Y'all rock. Thank you for the update and your work on this pressing issue. Now a fix for #788 is needed, and the theme's major forward-facing filtering issues will be resolved. 🥇

See also another related issue to #788 issue — #1596