Get child and parent category name (custom taxonomy) from current post (custom post type)

Question

I am trying to get the parent category and child category from the current post.
The custom post type is called assortiment and the custom taxonomy is called assortiment-categorie .

We have a product called SL524CB – 500kg with parent category Test and subcategory (of Test ) test b .

Now I did make a loop which outputs the sub category name ( test b ) but we also want the parent category name ( Test ).

To output them we want 2 variables like $parent_category and $subcategory so we can output them in our template.

This is the loop we are using right now:

<?php 
    global $post;
    $terms = wp_get_object_terms( $post->ID, 'assortiment-categorie', array('fields'=>'names'));
    $term_id = array_pop( $terms ); //gets the last ID in the array
    echo $term_id;
?>

If someone could help me that would be great, thanks for your time already!

Answer 1

There is a multitude of ways we can achieve that.

@Chris Haas comment is one way to do it. Me, I prefer using an alternative way.

Regarding parents, we can use get_term_parents_list() which will return a specific term's parents.

Retrieves term parents with separator.

<?php

$args = array(
    'format' => 'slug',
    'link' => false,
    'inclusive' => false,
);
  
$parents = explode( '/', get_term_parents_list( $term_id, $taxonomy, $args ) );

$î = 0;
foreach( $parents as $parent ) {
    $i++;

    echo $parent;

    if ( $i !== sizeof( $parents ) )
        echo ', ';

};

Regarding children, we can use get_term_children() which will return a specific term's children.

Merge all term children into a single array of their IDs.

<?php

$children = get_term_children( $term_id, $taxonomy );

$î = 0;
foreach( $children as $child ) {
    $i++;

    $term = get_term_by( 'id', $child, $taxonomy );

    echo $term->name;

    if ( $i !== sizeof( $children ) )
        echo ', ';

};

Answer 2

Use get_the_terms() .

$categories = get_the_terms( get_the_ID(), 'category' );
echo "<pre>"; print_r($categories); echo "</pre>"; 

If you print $categories then you will have an output like below. where you can determine that $term is parent or child .

Array
(
    [0] => WP_Term Object
        (
            [term_id] => 18
            [name] => Test 2
            [slug] => test-2
            [term_group] => 0
            [term_taxonomy_id] => 18
            [taxonomy] => category
            [description] => 
            [parent] => 17
            [count] => 1
            [filter] => raw
        )

    [1] => WP_Term Object
        (
            [term_id] => 17
            [name] => Test
            [slug] => test
            [term_group] => 0
            [term_taxonomy_id] => 17
            [taxonomy] => category
            [description] => 
            [parent] => 0
            [count] => 1
            [filter] => raw
        )

)

Try this below code.

foreach ( $categories as $key => $category ) {
    if( $category->parent == 0 ){
        echo "Parent => ".$category->name;
    }
}