Reordering array of objects in Wordpress

Question

I am writing custom WordPress script which is supposed to show all custom taxonomies in element. Some of these elements have children, others don't. Here is the code for the form:

                            <?php 
                            $terms = get_terms("location", "hide_empty=0");

                             $count = count($terms);
                             if ( $count > 0 ){
                                 foreach ( $terms as $term ) {
echo "<option value='" . $term->slug . "'>" . $term->name ."</option>";
                                 }
                             }

                        echo "</select>";

The problem is, it shows all the elements in alphabetical order, both parents and children. I want children to be nested below the parents but I am not able to figure out how. Can anyone offer some help?

Here is print_r of the $terms array:

Array
(
[0] => stdClass Object
    (
        [term_id] => 18
        [name] => Andrijevica
        [slug] => andrijevica
        [term_group] => 0
        [term_taxonomy_id] => 18
        [taxonomy] => location
        [description] => 
        [parent] => 0
        [count] => 0
    )

[1] => stdClass Object
    (
        [term_id] => 19
        [name] => Berane
        [slug] => berane
        [term_group] => 0
        [term_taxonomy_id] => 19
        [taxonomy] => location
        [description] => 
        [parent] => 0
        [count] => 0
    )

[2] => stdClass Object
    (
        [term_id] => 17
        [name] => Bijelo Polje
        [slug] => bijelo-polje
        [term_group] => 0
        [term_taxonomy_id] => 17
        [taxonomy] => location
        [description] => 
        [parent] => 0
        [count] => 0
    )

.....
[29] => stdClass Object
    (
        [term_id] => 53
        [name] => Pobrežje
        [slug] => pobrezje
        [term_group] => 0
        [term_taxonomy_id] => 63
        [taxonomy] => location
        [description] => 
        [parent] => 4
        [count] => 0
    )

[30] => stdClass Object
    (
        [term_id] => 4
        [name] => Podgorica
        [slug] => podgorica
        [term_group] => 0
        [term_taxonomy_id] => 4
        [taxonomy] => location
        [description] => 
        [parent] => 0
        [count] => 7
    )

As you can see parent is 0 for parents. Children have parent value set to term_id of the parent. For example [30] is parent of [29].

Answer 1

use get_term_children() inside the loop .

Example :

$taxonomyName = "location"
$terms = get_terms($taxonomyName,array('parent' => 0));
foreach($terms as $term) {
    echo '<a href="'.get_term_link($term->slug,$taxonomyName).'">'.$term->name.'</a>';
    $term_children = get_term_children($term->term_id,$taxonomyName);
    echo '<ul>';
    foreach($term_children as $term_child_id) {
        $term_child = get_term_by('id',$term_child_id,$taxonomyName);
        echo '<li><a href="' . get_term_link( $term_child->name, $taxonomyName ) . '">' . $term_child->name . '</a></li>';
    }
    echo '</ul>';
}

sorry, the example is cut and paste from one of my projects and will create a nested UL.. if you need it for a dropdown options - well - I am sure you can modify it for your needs..