Order get_terms by multiple meta_values

Question

I'm trying to get all the terms of a custom taxonomy (ediciones) but ordered by two ACF fields: edicion_ano (year field) and edicion_numero (number field). First should order by year and next by the number field.

I understand from ACF (5.5.X) it's possible to use meta_query and I'm ussing version 5.5.14.

In the new version of ACF (5.5.x) now uses term meta and WP allows meta queries for terms, so these work-arounds should no longer be needed. (source)

Right now I'm using this code:

$args = array(
    'taxonomy' => 'ediciones',
    'hide_empty' => false,
    'meta_query' => array(
        'relation' => 'AND',
        'edicion_ano_param' => array(
            'key' => 'edicion_ano',
            'compare' => 'EXISTS',
        ),
        'edicion_numero_param' => array(
            'key' => 'edicion_numero',
            'compare' => 'EXISTS',
        ), 
    ),
    'orderby' => array( 
        'edicion_ano_param' => 'DESC',
        'edicion_numero_param' => 'DESC',
    ),
);

$ediciones = get_terms($args);

Using the same meta_query but with get_posts() it's working fine. Actually with get_terms() show me a warning but I don't know why: Warning: strtolower() expects parameter 1 to be string, array given in .../class-wp-term-query.php on line 824

If I try order just for one field works fine with this code:

$args = array(
    'taxonomy' => 'ediciones',
    'hide_empty' => false,
    'meta_key' => 'edicion_ano',
    'orderby' => 'meta_value',
    'order' => 'DESC',
);

$ediciones = get_terms($args);

But I need order by both fields. Any idea what I'm doing wrong or how can make this works how I need?

Thanks!

Answer 1

That is because get_terms() does not accept array type as a value for the 'orderby' parameter. The documentation says about this parameter:

'orderby'

(string) Field(s) to order terms by. Accepts term fields ('name', 'slug', 'term_group', 'term_id', 'id', 'description'), 'count' for term taxonomy count, 'include' to match the 'order' of the $include param, 'meta_value', 'meta_value_num', the value of $meta_key, the array keys of $meta_query, or 'none' to omit the ORDER BY clause. Defaults to 'name'.

You can see here the original documentation page