Order get_terms using a Custom Field

Question

I have a custom taxonomy of "crb_issues" that has a custom field associated with it that is "issue_date" which outputs a date value for each term to looks a lot like "20140601" yearmonthday.

I am trying to out put all the Taxonomies terms using get_terms and order them by that custom field. Below is the code I have been working on which outputs the Terms Name and the value of the "issue_date" just fine. But I am having a hard time getting what is outputting to order by that custom field.

$args = array(
    'meta_key'          => 'issue_date',
    'orderby'           => 'meta_value_num', 
    'order'             => 'DESC',
    'hide_empty'        => true,
    'number'            => '4', 
    'fields'            => 'all', 
); 

$terms = get_terms("crb_issues", $args);

 if ( !empty( $terms ) && !is_wp_error( $terms ) ){
    echo "<ul>";
    foreach ( $terms as $term ) {
        echo "<li>" . $term->name . "</li>";
        the_field('issue_date', $term);
    }
    echo "</ul>";
 }

Any help would be much appreciated.

Answer 1

Rather than outputting your terms in that initial loop, I would use it instead to build a new array, with your issue_date as the key:

$my_new_array = array( );
foreach ( $terms as $term ) {
    $issue_date = get_field( 'issue_date', $term );
    $my_new_array[$issue_date] = $term->name;
}

You can then loop through this new array in order:

ksort( $my_new_array, SORT_NUMERIC );

foreach ( $my_new_array as $issue_date => $term_name ) {
   echo "<li>" . $term_name . " " . $issue_date . "</li>";
}

This is untested.

Answer 2

A much shorter solution, just add this before foreach:

usort($terms, function($a, $b) {
    return get_field('issue_date', $a) - get_field('issue_date', $b);
});

Answer 3

I used a similar method, but I wanted to store more values from the taxonomy than the name and custom field value I gave, so I ended up storing it as an object and creating an array much like what is actually returned when you use the function get_terms.

Get your terms:

$terms = get_terms('your-taxonomy');

Then create a new array, storing them by my custom field value, which happened to be numeric in this case:

$newterms = array(); 
foreach($terms as $term) {
    $order = get_field('order', $term); //THIS MY CUSTOM FIELD VALUE                
    $newterms[$order] = (object) array(
            'name' => $term->name,
            'slug' => $term->slug,
            'term_id' => $term->term_id
    );
}

Sort them numerically:

ksort( $newterms, SORT_NUMERIC );

Then use the foreach loop to get the values of each object:

foreach ( $newterms as $newterm ) {     
        echo '<a href="#' . $newterm->slug . '">' . $newterm->name . '</a>';
}

So, essentially I am rewriting the array to use the key of my custom order, but in this case I needed the slug, name, and ID of the term, so I stored it as an object, rather than the method above.

My end goal was I set up an Advanced Custom Field so when a taxonomy term was created, it could be given a numerical order from the user, and then I could loop through the terms based on their desired order.

Hope this helps someone!

Answer 4

Thanks Vancoder for your help!!! I have been ripping my hair out all day trying to figure it out. Funny enough your solution was one of half a dozen I wrote on my whiteboard, BUT I had no clue how to actually create an array with that as a key. I am a noob like that. Below is the code I ended up using with some comments for anyone else trying to do this!

<?php
$terms = get_terms("crb_issues");
$issue_archive = array( ); // creates an array for all terms inside of crb_issues tax using the custom field "issue_date" as the key
foreach ( $terms as $term ) {
    $issue_date = get_field( 'issue_date', $term );
    $issue_archive[$issue_date] = $term->name;
}

krsort( $issue_archive, SORT_NUMERIC ); //sorts the issue_archive array from high to low

foreach ( $issue_archive as $issue_date => $term_name ) {
    echo "<li>" . $term_name . " " . $issue_date . "</li>"; //displays the term name and customfield issue_date
    if (++$i == 4) break; //Stops the foreach after 4
}
?>

If anyone has better comments for this code please let me know, or better ways to handle anything. But I think this is a pretty awesome solution.

Answer 5

Thanks Phil Hoyt, this was exactly what I was looking for. But, alas, I couldn't get it to work with my setup. What does work is the following:

    <?php
    // Solution for sorting by ACF custom-field for tracks categories
    // http://support.advancedcustomfields.com/forums/topic/sorting-categories-list-by-custom-field/
    $categories = get_categories('taxonomy=tracks');
    $sorted_cats = array();
    foreach($categories as $cat){
    //$ordr = get_field('track_order', 'tracks_'.$cat>term_id); //wasn't working so used the line below
        $ordr = get_field( 'track_order', $cat );
        $sorted_cats[$ordr] = $cat;
    }
    krsort($sorted_cats);//ksort orders ascending, krsort reverses order (i.e. biggest to smallest)
    ?>

Cheers

Answer 6

Sort terms by array value 'order' instead of array key. If you have 2 items with same key, last one will override first one. This will prevent that and make all of them visible:

$sorted = array();
$args   = array( 'hide_empty' => false );
$terms  = get_terms( 'my-tax', $args );

if( $terms ) : 

    foreach ( $terms as $term ) {

        $sorted[]  = array(
            'order' => get_field( 'order', $term ), // Get field from ACF
            'name'  => $term->name,
        );
    }

    function sortByOrder($a, $b) {
        return $a['order'] - $b['order'];
    }

    usort($sorted, 'sortByOrder');

    foreach( $sorted as $t ) :?>
        <span>
            <?php echo $t['name']; ?>
        </span>
    <?php endforeach;
endif;