How to get a custom type post data when it has a connection with another custom type post?

Question

I have two custom post types: Country and City.

Country

There is just a text field to fill with its name.

City

I have a text field for city's name and also a select with all the countries that was added in the other custom post type.

My question is, how to get for each city, its own country?

To retrieve the cities I'm using:

$args = array (
  'post_type' => 'cities'
);
$query = new WP_Query($args);

In this result of cities, I don't have any information related to the country that I select in the admin area.

Thanks!

Answer 1

If in a country looking for cities

$args = array (
    'post_type' => 'cities',
    'meta_key' => 'country',
    'meta_value' => get_the_ID()
);

This assumes that the "Country > Name* > [drop down]" you screenshot saves that the selected value using post_meta and is saving the country's post ID. (If it does not please adjust or specify).

UPDATE

To list cities, and retrieve their country_name, assuming the dropdown is just storing the post_title of the country, you could do:

$cities = get_posts(array (
    'post_type' => 'cities',
    'numberposts' => '-1',
));
foreach ($cities as $city) {
    $country_name = get_post_meta($city->ID,'country_name',true);
    // to get the full country, if country_name is just the post title (and not ID) you could do
    # $country = get_page_by_title( $country_name, 'object', 'country' );
    echo "<pre>City: {$city->post_title} is in country: {$country_name}</pre>":
}