How to display posts categories as classes - php

Question

Seems that I am just too stupid to achieve this. Seems so simple, yet…
I created a template and try to display a custom portfolio (registered by a custom post plugIn) This works fine with the following code:
<div id="container">
<?php
//Define your custom post type name in the arguments
$args = array('post_type' => 'boxes_scientists');
//Define the loop based on arguments
$loop = new WP_Query( $args );
//Display the contents
while ( $loop->have_posts() ) : $loop->the_post();
?>
/*
<?php
foreach((get_the_category()) as $category) {
echo $category->cat_name . ' ';
}
?>
<?php the_category(', '); ?>
*/
<div class="some_base_class [categories of the post need to go here]">
<a class="element" href="<?php the_permalink(); ?>"></a>
<div class="portfolio-box">
<div class="portfolio-naming">
<h2 class="portfolio-title"><?php the_title(); ?></h2>
<h3 class="portfolio-attributes"><?php the_content(); ?></h3>
</div>
</div>
<?php the_post_thumbnail(); ?>
</div>
<?php endwhile;?>
but I can’t get to work the commented out code part and display the categories inside the class tag of my container element (for each post displayed in the loop).
I actually found also this concept:
https://lorelle.wordpress.com/2007/09/06/using-wordpress-categories-to-style-posts
which seemed to be exactly what I need but sadly this didn’t work at all for me. (placed the function inside functions.php on my child theme and theme both without any result)
What I am misunderstanding here? Can someone show me the correct code I have to use? Would be so awesome. Thanks in advance!
EDIT
So this finally brings me on the right way:
<?php
[…]
$category = get_the_category();
$firstCategory = $category[0]->cat_name;?>
<div class="some_base_class <?php echo $firstCategory ?>">
I missed the “echo” thing inside my div. Now I will have to find the way to display all categories of my post instead of only the first.
EDIT 2:
<div id="boxes_section" class="main-content master-section-content nano_boxes no-detect no-padding">
<div class="container">
<div class="row">
<div class="col-md-12 normal-column start-animated-content az-fade-in" data-delay="300">
<div class="blank-divider" style="height: 30px;"></div>
<div id="portfolio-item-section" class="portfolio-output masonry-ly-portfolio classic-module no-pagination" data-cols="3">
<?php
//Define your custom post type name in the arguments
$args = array('post_type' => 'boxes_scientists');
//Define the loop based on arguments
$loop = new WP_Query( $args );
//Display the contents
while ( $loop->have_posts() ) : $loop->the_post();
?>
<div class="single-portfolio-item az-col-full-width-4 [NEED THE CLASSES HERE]">
<a class="classic-portfolio-box normal-type-prt" href="<?php the_permalink(); ?>">
<p class="site_leave"><i class="font-icon-forward"></i>You are going to leave this website</p>
</a>
<div class="portfolio-box">
<div class="portfolio-naming">
<h2 class="portfolio-title"><?php the_title(); ?></h2>
<h3 class="portfolio-attributes"><?php the_content(); ?></h3>
</div>
</div>
<?php the_post_thumbnail(); ?>
</div>
<?php endwhile;?>
</div>
</div>
</div>
</div>
</div>

Answer 1

I just write code category at functions.php like this:
function sps_category(){
$categories = get_the_category();
foreach ( $categories as $category ) {
echo '<a href="'.esc_url( get_category_link( $category->term_id ) ).'">
'.esc_html( $category->cat_name ).'
</a>';
}
}
and i call my functions at my page
<?php sps_category() ?>
but in other ways,
you can write your code in class like this:
$categories = get_the_category();
foreach ( $categories as $category ) {
echo '<div class=".esc_attr($category->cat_name)."><a href="'.esc_url( get_category_link( $category->term_id ) ).'">
'.esc_html( $category->cat_name ).'
</a><div>';
}
It can editable and dynamic if you want to show just 1 category.
And dont forget to use escape function if you put some php variabel/functions if you write in attribut html
for example use esc_attr(somecode) if it class/title/name/id attribute.