I have many uses for this but I want to know the most performant way of doing what is going to be an expensive operation.
As an example I will use a shop.
- A product brand taxonomy
- A product group taxonomy
- A product post type
- Archive templates for the above taxonomies
What is the most efficient, performant method, of showing a brand menu when in a product type archive, and a product type when in a brand archive, but, only show the terms that apply to the posts in that group.
So for example, if I am in the product group 'womens', it would show brands on the left hand side, but only the brands that are specified for products in the 'womens' product group. E.g. the brand 'Fancy womens clothes Inc' would show, but not 'Manly mens Manly ltd'.
I need a generic answer, though I'm happy for the clothing products example to be used, and I know how to do this with a greedy algorithm by brute force, but that's incredibly wasteful, and I'm not interested in a solution that would increase every page load by several seconds and load all the posts in full from the DB in the process
edit: Example 2:
Pikachu is a yellow pokemon, and is in the yellow tag, but Pikachu is also an electric pokemon, so it's in the electric tag of the type taxonomy. How would I show only the types of pokemon that are yellow when in the yellow tag archive? e.g. all grass pokemon being green means that there would not be a grass menu item when in the yellow archive but there would in the green ( yes I know there are grass pokemon that aren't green )