Using the WordPress in_category() function

My biggest project at work is the Delaware COVID-19 information website. It is built in WordPress.

I recently had a problem to solve where I wanted alert boxes to automatically display in the language that the page was translated into. We have pages in the three most spoken languages in Delaware: English, Spanish, and Haitian Creole.

I decided to approach it by assigning specific categories to the Spanish and Haitian Creole pages. I was then able to use the WordPress in_category() function to identify which categories that page belonged to.

This applied to single pages, so in page.php, my code looked something like this:

<?php
   if(in_category('spanish')) {
      include 'includes/spanish-file.php';
   } elseif(in_category('haitian-creole')) {
      include 'includes/haitian-creole-file.php';
   } else {
      include 'english-file.php';
   }
?>

This if statement first looks to see if the category assigned to the page is "spanish", and if it is, then the PHP include function displays the content within spanish-file.php.

If the category is not "spanish", then it looks to see if it is "haitian-creole", and if it is, then it displays the contents of haitian-creole-file.php.

If the category doesn't match either of those, then it displays english-file.php.

The majority of pages on the website are in English, so I didn't feel the need to assign an English category and simply included it in the "else" condition for all pages that had neither "spanish" or "haitian-creole" assigned to it.

I wrote this function in the page.php file. I'm sure there are arguments against doing that. If you wanted to, you could also define it as a function in the functions.php file and then call the function in page.php. If you did it that way, it would look something like this:

In functions.php:

<?php
   function multi_language_page_files() {
      if(in_category('spanish')) {
         include 'includes/spanish-file.php';
      } elseif(in_category('haitian-creole')) {
         include 'includes/haitian-creole-file.php';
      } else {
         include 'english-file.php';
      }
   }

No closing PHP ?> tag needed in the functions.php file.

Then, you would call the function in page.php:

<?php multi_language_page_files() ?>

I hope this helps. I was not previously aware of the in_category() function before I found it yesterday. It is extremely helpful in this case!