Hello
I have 2 custom taxonomies – ‘country’ and ‘city’, which represent all countries and cities respectively. Countries are pre-populated on my plugin install, when this custom taxonomy is created. Cities are added later and we connect them to countries via ACF.
The location for field group is: Taxonomy Term = ‘city’.
There’s only one field there: ‘country’, which is ‘Relationship’ – ‘Taxonomy’.
It works just fine in wp-admin – when there’s new city added we can select to which country it belongs and save the data.
Now I’m building a custom front-end registration form where user can select his country (done, no problems) and then the ‘city’ select will should be populated only with cities belonging to this country, not all of them.
I’ve read the docs and tuts and found some useful code to get this:
echo '<p>Cities and their countries</p>';
foreach( $cities as $city ) {
$city_id = 'city_'.$city->term_id;
$country_id = get_field( 'country', $city_id );
$country = get_term($country_id, 'country');
echo $city->name.' ('.$country->name.')<br>';
}
It easily prints a list of cities showing their countries. The most interesting part of the code is the format of $city_id argument – taxonomyname_taxonomyid.
Now I tried to reverse it and got this:
echo '<p>Countries with their cities</p>';
echo $country->name.'<br>';
$cities = get_terms('city', array('hide_empty'=>false));
foreach( $cities as $city ) {
$acfcity_id = 'city_'.$city->term_id;
$acfcountry_id = get_field( 'country', $acfcity_id );
$acfcountry = get_term($acfcountry_id, 'country');
if( $acfcountry->name == $country->name )
echo ' - '.$city->name.'<br>';
}
It prints the list of cities only for one country and it works. But it is far from being effective and fast – when the list of cities will be large, this foreach will take some time to loop through. Is there a better way of getting a list of cities which have particular country in ACF taxonomy relationship field? Or is this the only way and the only workaround will be to persistently cache those calculated results (a list of cities per one country)?
