How to pass parameters from a PHP file to the template?

Question

I have a website made with WP (a customer passed me). He want to see in one of the pages, a list of product categories, and to get the list of this product categories, I have to send a request to an API in another website. The site will response with an XML that contain the categories. To make the request I will use some PHP library. After the response is arrived, I want to show those categories in the page of my site of my customer.

I have followed the first answer here to call a php file before rendering a template, but imagine that I want to pass a variable (product categories) from the php to to the template. How can I do that?

Answer 1

You will probably want to cache the results of the XML that comes back to you (unless it is truely dynamic), and possibly store it in a table. You can decide how often you need to refresh the cache. (This will protect your site and their API from DOS attacks, or even just high volume).

Once you have your data stored in a table, your template can simply retrieve it.

This pattern will reduce the coupling between the two parts of your solution, and make things a bit easier to build / debug.