I have a hierarchical taxonomy called 'geographical locations'. It contains continents on a first level, and then the countries for each one. Example :
Europe
- Ireland
- Spain
- Sweden
Asia
- Laos
- Thailand
- Vietnam
etc.
Using get_terms() I managed to output the full list of terms, but the continents get mixed up with the countries, in one big flat list.
How can I output a hierarchical list like above?
Use wp_list_categories with the 'taxonomy' => 'taxonomy' argument, it's built for creating hierarchical category lists but will also support using a custom taxonomy..
Codex Example:
Display terms in a custom taxonomy
If the list comes back looking flat, it's possible you just need a little CSS to add padding to the lists, so you can see their hierarchical structure.
I realize, this is a very old question, but if you have a need to build up an actual structure of terms, this might be a useful method for you:
/**
* Recursively sort an array of taxonomy terms hierarchically. Child categories will be
* placed under a 'children' member of their parent term.
* @param Array $cats taxonomy term objects to sort
* @param Array $into result array to put them in
* @param integer $parentId the current parent ID to put them in
*/
function sort_terms_hierarchically(Array &$cats, Array &$into, $parentId = 0)
{
foreach ($cats as $i => $cat) {
if ($cat->parent == $parentId) {
$into[$cat->term_id] = $cat;
unset($cats[$i]);
}
}
foreach ($into as $topCat) {
$topCat->children = array();
sort_terms_hierarchically($cats, $topCat->children, $topCat->term_id);
}
}
Usage is as follows:
$categories = get_terms('my_taxonomy_name', array('hide_empty' => false));
$categoryHierarchy = array();
sort_terms_hierarchically($categories, $categoryHierarchy);
var_dump($categoryHierarchy);
$into[$cat->term_id] = $cat; into $into[] = $cat; Having the ID of the term as the array key is annoying (you can't get the first element easily using the 0 key) and useless (you're already storing the $cat object and you can get the id using the term_id property.
I dont know of any function that does what you want but you can build up something like this:
<ul>
<?php $hiterms = get_terms("my_tax", array("orderby" => "slug", "parent" => 0)); ?>
<?php foreach($hiterms as $key => $hiterm) : ?>
<li>
<?php echo $hiterm->name; ?>
<?php $loterms = get_terms("my_tax", array("orderby" => "slug", "parent" => $hiterm->term_id)); ?>
<?php if($loterms) : ?>
<ul>
<?php foreach($loterms as $key => $loterm) : ?>
<li><?php echo $loterm->name; ?></li>
<?php endforeach; ?>
</ul>
<?php endif; ?>
</li>
<?php endforeach; ?>
</ul>
I haven't tested this but you can see what I'm getting at. What the above code will do is give you only two levels
EDIT: ahh yes you can use wp_list_categories() to do what you after.
wp_list_categories() to add in your GET parameters. Or even better build a filter for the function to add in the bits you want. Don't ask me how you do that as I've not yet been able to get my head around it :(
wp_list_categories if you want greater control over the output, it'll make your code much more reusable..
You can use wp_list_categories(), with a 'taxonomy' argument.
The following code will generate drop-down with terms, but also can generate any other element/structure by editing the $outputTemplate variable, and editing str_replace lines:
function get_terms_hierarchical($terms, $output = '', $parent_id = 0, $level = 0) {
//Out Template
$outputTemplate = '<option value="%ID%">%PADDING%%NAME%</option>';
foreach ($terms as $term) {
if ($parent_id == $term->parent) {
//Replacing the template variables
$itemOutput = str_replace('%ID%', $term->term_id, $outputTemplate);
$itemOutput = str_replace('%PADDING%', str_pad('', $level*12, ' '), $itemOutput);
$itemOutput = str_replace('%NAME%', $term->name, $itemOutput);
$output .= $itemOutput;
$output = get_terms_hierarchical($terms, $output, $term->term_id, $level + 1);
}
}
return $output;
}
$terms = get_terms('taxonomy', array('hide_empty' => false));
$output = get_terms_hierarchical($terms);
echo '<select>' . $output . '</select>';
I used @popsi code that was working really well and I made it a more efficient and easy to read:
/**
* Recursively sort an array of taxonomy terms hierarchically. Child categories will be
* placed under a 'children' member of their parent term.
* @param Array $cats taxonomy term objects to sort
* @param integer $parentId the current parent ID to put them in
*/
function sort_terms_hierarchicaly(Array $cats, $parentId = 0)
{
$into = [];
foreach ($cats as $i => $cat) {
if ($cat->parent == $parentId) {
$cat->children = sort_terms_hierarchicaly($cats, $cat->term_id);
$into[$cat->term_id] = $cat;
}
}
return $into;
}
Usage :
$sorted_terms = sort_terms_hierarchicaly($terms);
As I was looking for the same but to get terms of one post, finally I compiled this, and it works for me.
What it does :
• it gets all terms of a taxonomy name for a specific post.
• for a hierachical taxonomy with two levels (ex: level1:'country' and level2:'cities'), it creates a h4 with the level1 followed by an ul list of level2 and this for all level1 items.
• if the taxonomy is not hierarchical, it will create only an ul list of all items.
here is the code (I write it for me so I tried to be as generic as I can but...) :
function finishingLister($heTerm){
$myterm = $heTerm;
$terms = get_the_terms($post->ID,$myterm);
if($terms){
$count = count($terms);
echo '<h3>'.$myterm;
echo ((($count>1)&&(!endswith($myterm, 's')))?'s':"").'</h3>';
echo '<div class="'.$myterm.'Wrapper">';
foreach ($terms as $term) {
if (0 == $term->parent) $parentsItems[] = $term;
if ($term->parent) $childItems[] = $term;
};
if(is_taxonomy_hierarchical( $heTerm )){
foreach ($parentsItems as $parentsItem){
echo '<h4>'.$parentsItem->name.'</h4>';
echo '<ul>';
foreach($childItems as $childItem){
if ($childItem->parent == $parentsItem->term_id){
echo '<li>'.$childItem->name.'</li>';
};
};
echo '</ul>';
};
}else{
echo '<ul>';
foreach($parentsItems as $parentsItem){
echo '<li>'.$parentsItem->name.'</li>';
};
echo '</ul>';
};
echo '</div>';
};
};
So finally you call the function with this (obviously, you replace my_taxonomy by yours) : finishingLister('my_taxonomy');
I don't pretend it's perfect but as I said it works for me.
I had this problem and none of the answers here worked for me, for one reason or another.
Here is my updated and working version.
function locationSelector( $fieldName ) {
$args = array('hide_empty' => false, 'hierarchical' => true, 'parent' => 0);
$terms = get_terms("locations", $args);
$html = '';
$html .= '<select name="' . $fieldName . '"' . 'class="chosen-select ' . $fieldName . '"' . '>';
foreach ( $terms as $term ) {
$html .= '<option value="' . $term->term_id . '">' . $term->name . '</option>';
$args = array(
'hide_empty' => false,
'hierarchical' => true,
'parent' => $term->term_id
);
$childterms = get_terms("locations", $args);
foreach ( $childterms as $childterm ) {
$html .= '<option value="' . $childterm->term_id . '">' . $term->name . ' > ' . $childterm->name . '</option>';
$args = array('hide_empty' => false, 'hierarchical' => true, 'parent' => $childterm->term_id);
$granchildterms = get_terms("locations", $args);
foreach ( $granchildterms as $granchild ) {
$html .= '<option value="' . $granchild->term_id . '">' . $term->name . ' > ' . $childterm->name . ' > ' . $granchild->name . '</option>';
}
}
}
$html .= "</select>";
return $html;
}
And usage:
$selector = locationSelector('locationSelectClass');
echo $selector;
This solution is less efficient than @popsi's code, since it makes a new query for every term, but it's also easier to use in a template. If your website uses caching, you may, like me, not mind the slight database overhead.
You don't need to prepare an array that'll be recursively filled with terms. You just call it the same way you would call get_terms() (the non-deprecated form with only an array for an argument). It returns an array of WP_Term objects with an extra property called children.
function get_terms_tree( Array $args ) {
$new_args = $args;
$new_args['parent'] = $new_args['parent'] ?? 0;
$new_args['fields'] = 'all';
// The terms for this level
$terms = get_terms( $new_args );
// The children of each term on this level
foreach( $terms as &$this_term ) {
$new_args['parent'] = $this_term->term_id;
$this_term->children = get_terms_tree( $new_args );
}
return $terms;
}
Usage is simple:
$terms = get_terms_tree([ 'taxonomy' => 'my-tax' ]);
One final death-blow to this horse (similar to the above answers) with a bit more refinement ... allowing you to also transform the list into a hierarchically-flat list with a depth param.
Additionally, this function uses clone to avoid modifying the original array.
/**
* Sort terms object list hierarchically or hierarchically-flat.
*/
function sort_terms_hierarchically( $terms, $parent_id = 0, $flat = FALSE, $depth = 0 ) {
$data = [];
foreach ( $terms as $term ) {
if ( $parent_id != $term->parent ) continue;
$data_term = clone $term;
$data_term->depth = $depth;
$children = sort_terms_hierarchically( $terms, $term->term_id, $flat, $depth + 1 );
if ( ! $flat ) $data_term->children = $children;
$data[] = $data_term;
if ( $flat ) foreach( $children as $child ) $data[] = $child;
}
return $data;
}
function sort_terms_hierarchically_flat( $terms, $parent_id = 0 ) {
return sort_terms_hierarchically( $terms, $parent_id, TRUE );
}
Usage is as follows:
$terms = get_terms( [
'taxonomy' => 'regions',
'hide_empty' => FALSE,
] );
$terms_sorted = sort_terms_hierarchically( $terms );
$terms_sorted_flat = sort_terms_hierarchically_flat( $terms );
Be sure that hierarchical=true is passed to your get_terms() call.
Note that hierarchical=true is the default, so really, just be sure that it hasn't been overridden to be false.
get_terms() will return a full list of the terms (as the OP stated) but not a hierarchical list showing parent / child relationship as requested.
Here I have four level dropdown select list with hidden first item
<select name="lokalizacja" id="ucz">
<option value="">Wszystkie lokalizacje</option>
<?php
$excluded_term = get_term_by('slug', 'podroze', 'my_travels_places');
$args = array(
'orderby' => 'slug',
'hierarchical' => 'true',
'exclude' => $excluded_term->term_id,
'hide_empty' => '0',
'parent' => $excluded_term->term_id,
);
$hiterms = get_terms("my_travels_places", $args);
foreach ($hiterms AS $hiterm) :
echo "<option value='".$hiterm->slug."'".($_POST['my_travels_places'] == $hiterm->slug ? ' selected="selected"' : '').">".$hiterm->name."</option>\n";
$loterms = get_terms("my_travels_places", array("orderby" => "slug", "parent" => $hiterm->term_id,'hide_empty' => '0',));
if($loterms) :
foreach($loterms as $key => $loterm) :
echo "<option value='".$loterm->slug."'".($_POST['my_travels_places'] == $loterm->slug ? ' selected="selected"' : '')."> - ".$loterm->name."</option>\n";
$lo2terms = get_terms("my_travels_places", array("orderby" => "slug", "parent" => $loterm->term_id,'hide_empty' => '0',));
if($lo2terms) :
foreach($lo2terms as $key => $lo2term) :
echo "<option value='".$lo2term->slug."'".($_POST['my_travels_places'] == $lo2term->slug ? ' selected="selected"' : '')."> - ".$lo2term->name."</option>\n";
endforeach;
endif;
endforeach;
endif;
endforeach;
?>
</select>
<label>Wybierz rodzaj miejsca</label>
<select name="rodzaj_miejsca" id="woj">
<option value="">Wszystkie rodzaje</option>
<?php
$theterms = get_terms('my_travels_places_type', 'orderby=name');
foreach ($theterms AS $term) :
echo "<option value='".$term->slug."'".($_POST['my_travels_places_type'] == $term->slug ? ' selected="selected"' : '').">".$term->name."</option>\n";
endforeach;
?>
</select>
