How to create a array that contains all of the children slugs of a specific parent category

Question

I need to create an Array that contains all of the children slugs of a specific parent category ID.

Let's say I have the following parent category and its children categories:

1. Food
   • pizza
   • bread
   • banana
   • ice cream

I need a code/function to use inside functions.php that returns the slugs of all of the children's slug of a specific parent category like this:

function-get-child-slug( $parentID='1');

It returns this:

array('pizza','bread','banana','ice-cream')

---

I've tried some variants of this but it didn't work:

$var = wp_list_categories( array( 
        'child_of'           => 1,
         'echo'              =>false
    ) ); 
$array = array(strip_tags($var));

How can I achieve this?

Answer 1

You can use get_terms() to get an array of child slugs:

/**
 * Get child term slugs from given term parent
 *
 * @param Integer $parent_id ( Parent Term ID )
 * @param String $taxonomy ( Taxonomy Slug )
 *
 * @return Array( $term_id => $child_slug )
 */
function get_child_slugs( $parent_id = 0, $taxonomy = 'category' ) {
    return get_terms( array(
        'taxonomy'  => $taxonomy,
        'parent'    => $parent_id,
        'fields'    => 'id=>slug',
    ) );
}

This should return a simple array of array( $term_id => $term_slug ) assuming a valid parent term ID and valid taxonomy is supplied.

Answer 2

There's this get_term_children function you can use to list the child categories of a given category, it returns the IDs of child cats if found, and get_term can be used to get category information rather than just an ID.

function get_child_slug($parent=1, $tax='category') {
    if ( !is_numeric($parent) ) {
        $parent = get_term_by('name', $parent, $tax);
    } else {
        $parent = get_term( $parent );
    }

    if ( empty( $parent->term_id ) )
        return array();

    $children = get_term_children( $parent->term_id, $tax );

    if ( $children ) {
        $children = array_map('get_term', $children);
    }

    return $children;
}

Here's a dump test:

samuel@Samuel-PC:~/htdocs/multisite.dev/www$ wp eval 'print_r(get_child_slug("Food"));'
Array
(
    [0] => WP_Term Object
        (
            [term_id] => 3
            [name] => pizza
            [slug] => pizza
            [term_group] => 0
            [term_taxonomy_id] => 3
            [taxonomy] => category
            [description] => 
            [parent] => 2
            [count] => 0
            [filter] => raw
        )

    [1] => WP_Term Object
        (
            [term_id] => 4
            [name] => bread
            [slug] => bread
            [term_group] => 0
            [term_taxonomy_id] => 4
            [taxonomy] => category
            [description] => 
            [parent] => 2
            [count] => 0
            [filter] => raw
        )

    [2] => WP_Term Object
        (
            [term_id] => 5
            [name] => banana
            [slug] => banana
            [term_group] => 0
            [term_taxonomy_id] => 5
            [taxonomy] => category
            [description] => 
            [parent] => 2
            [count] => 0
            [filter] => raw
        )

    [3] => WP_Term Object
        (
            [term_id] => 6
            [name] => ice cream
            [slug] => ice-cream
            [term_group] => 0
            [term_taxonomy_id] => 6
            [taxonomy] => category
            [description] => 
            [parent] => 2
            [count] => 0
            [filter] => raw
        )

)

Hope that helps.