Post css colors based on category?

Hi prokops,

Thank you for starting a new topic. Don’t worry about mistakenly tagging on to someone else’s topic, we learn from our mistakes, I’m sure you won’t do that again here 🙂 And welcome to the community!

It’s puzzling why the solutions you linked did not work for you. It’s possible your theme or some other plugin is interfering with conventional functionality. Or it may simply be the class is not applied to the element you desire.

The correct approach depends on what your theme is currently doing for classes on the element you’re interested in. If the classes are coming from a template tag or function call on the applicable template, there’s a chance you could achieve what you want by hooking a filter or overriding a pluggable function. Otherwise, you probably need to directly alter the template code. When you alter theme templates or functions, you should create a child theme so theme updates do not overwrite your changes.

First identify the template that outputs the element where you want to add classes, then copy it to your child theme folder. I’m assuming this element is within The Loop, which greatly simplifies things. Then Lorelle’s approach should more or less work for you, though some alteration may be needed to work with your exact situation. She is basically creating a template tag function. The function declaration should go on you child theme’s functions.php file. The template tag should be called just like she suggests:
<div class="post<?php the_category_unlinked(' '); ?>">

Maybe your element is not a div, but the class attribute is declared the same way for most elements. You also need to be sure you keep HTML and PHP sections straight. If the HTML is output with PHP echo, you do not introduce another <?php ?> block, you cannot nest these blocks. The equivalent all PHP version would be like this:
echo '<div class="post' . get_the_category_unlinked(' ') . '">';

Note that I changed the template tag name. This is because the original version echoes out the category classes. In an all PHP version, the template tag should return a value instead of echoing it.

If you’re still having trouble, please post the relevant portion of your template code along with your version of Lorelle’s template tag function.