Get Custom Field Values by Another Custom Field in WordPress

Question

I have a custom post type named houses. Inside this post type I have several custom fields, like:

(name - field type - meta key)

• Title (wordpress field)
• City (taxonomy - city)
• Condominium (custom post type - condominium)
• Beach (custom post type - beach)
• Country (taxonomy - country)
• Description (custom field - description)
• Text (custom field - text)
• Bedrooms (custom field - bedrooms)
• Bathrooms (custom field - bathrooms)
• Type (taxonomy - type)
• Status (taxonomy - status)
• Area (custom field - area)
• Full Area (custom field - full_area)
• Place (taxonomy - place)

and more.

I have a plugin on my website with 4 selects:

• City
• Beach
• Type
• Status

What I need to do is, update these selects when I select an option.

For example, if I select Barcelona for City and Sale for Status, I need to retrieve all Types and Beaches with these options in common.

I don't need to get the posts now, just update the select options, like a filter.

Here an example:

PS: I'm using Advanced Custom Fields.

Answer 1

After struggling with this, I found a workaround that worked.

Since every custom field has a connection with my custom post type, I was able to use wp_get_object_terms to get the terms for each custom taxonomy.

Using the query to retrieve all posts:

$args = array(
   'post_type' => 'houses'
);
$houses = new WP_Query($args);
$posts = $houses->posts;

// get an array with all ID fields
$my_post_ids = wp_list_pluck($posts, 'ID');

After that I can get the terms for these IDs above:

$city_terms = wp_get_object_terms($my_post_ids, 'cities');
$status_terms = wp_get_object_terms($my_post_ids, 'status');
$type_terms = wp_get_object_terms($my_post_ids, 'type');

And to have the behavior I needed when an option is selected in order to refresh the selects information, I had just to update the query for that. For example, if I selected some city:

$args = array( 
  'post_type' => 'houses',
  'meta_query' => array(
    'relation' => 'AND',
      array(
        'key' => 'city',
        'value' => 107,
        'compare' => 'LIKE'
      )
    )
);

To do the filter, just need to add a new relation inside the meta_query array.

$args = array( 
  'post_type' => 'houses',
  'meta_query' => array(
    'relation' => 'AND',
      array(
        'key' => 'city',
        'value' => 107,
        'compare' => 'LIKE'
      ),
      array(
        'key' => 'status',
        'value' => 80,
        'compare' => 'LIKE'
      )
    )
);

All of this combined with Ajax to make the data update for each select.