Displaying Products by Category IDs Stored in a TV Field

Sometimes a catalog is not organized in the tree the way the frontend needs it. the core case here described a common workaround: products live in one separate folder, while each product stores its category membership inside a TV field as a comma-separated list of IDs.

That immediately creates a new problem: category pages can no longer rely on the parent-child tree alone. They need to query products by whether the current category ID exists inside that TV value.

What this architecture is good for

• A product can belong to several categories at once.
• The storage tree stays simple even when frontend navigation is more flexible.
• Cross-listing becomes easier than with strict one-parent placement.

The trade-off is that category rendering must move from tree logic to value-matching logic. Once you accept that, the implementation becomes clearer: treat category membership as data, not location.

This donor is worth keeping because many real Evolution stores eventually need this exact pattern.