How do I convert Custom Fields to a taxonomy? WordPress

Matt comments:

The custom fields are in the wp_postmeta table in the meta_key / meta_value columns

The taxonomies are in the wp_term_taxonomy table in the taxonomy / term_id columns... I think. Again, I'm not great with mysql and I don't know the difference between term_id and term_taxonomy_id nor do I quite understand the relationship between taxonomies and posts.

So for example, I have a custom field with meta_key cp_additional_options with a meta_value of "Photo Gallery" that needs to be changed to a taxonomy of pa_options and either a term_id of 3310 or term_taxonomy_id of 3759 or maybe both... I'm not really sure.

Does that help?

Daniel Yoen comments:

I think, you need custom taxonomy :

function add_custom_taxonomies()
{
register_taxonomy('pa_popular-features', 'post', array(
'hierarchical' => true,
'labels' => array(
'name' => _x('Popular Features', 'taxonomy general name'),
'singular_name' => _x('Popular Features', 'taxonomy singular name'),
'search_items' => __('Search Popular Features'),
'all_items' => __('All Popular Features'),
'parent_item' => __('Parent Popular Features'),
'parent_item_colon' => __('Parent Popular Features:'),
'edit_item' => __('Edit Popular Features'),
'update_item' => __('Update Popular Features'),
'add_new_item' => __('Add New Popular Features'),
'new_item_name' => __('New Popular Features Name'),
'menu_name' => __('Popular Features')
),
'rewrite' => array(
'slug' => 'pa_popular-features',
'with_front' => false,
'hierarchical' => true
)
));
}
add_action('init', 'add_custom_taxonomies', 0);


then, paste this line to header.php or index.php in theme folder

function generate_meta_keys()
{
global $wpdb;
$post_type = 'post';
$query = "
SELECT DISTINCT($wpdb->postmeta.meta_value)
FROM $wpdb->posts
LEFT JOIN $wpdb->postmeta
ON $wpdb->posts.ID = $wpdb->postmeta.post_id
WHERE $wpdb->posts.post_type = '%s'
AND $wpdb->postmeta.meta_key != ''
AND $wpdb->postmeta.meta_key NOT RegExp '(^[_0-9].+$)'
AND $wpdb->postmeta.meta_key NOT RegExp '(^[0-9]+$)'
";
$meta_keys = $wpdb->get_col($wpdb->prepare($query, $post_type));
return $meta_keys;
}
foreach (generate_meta_keys() as $metaval)
{
wp_insert_term($metaval, 'category');
}


Refresh your page, then check your backend in posts tab :-)

hope this help

Daniel Yoen comments:

sorry, revision

function generate_meta_keys()
{
global $wpdb;
$post_type = 'post';
$query = "
SELECT DISTINCT($wpdb->postmeta.meta_value)
FROM $wpdb->posts
LEFT JOIN $wpdb->postmeta
ON $wpdb->posts.ID = $wpdb->postmeta.post_id
WHERE $wpdb->posts.post_type = '%s'
AND $wpdb->postmeta.meta_key != ''
AND $wpdb->postmeta.meta_key NOT RegExp '(^[_0-9].+$)'
AND $wpdb->postmeta.meta_key NOT RegExp '(^[0-9]+$)'
";
$meta_keys = $wpdb->get_col($wpdb->prepare($query, $post_type));
return $meta_keys;
}
foreach (generate_meta_keys() as $metaval)
{
wp_insert_term($metaval, 'pa_popular-features'); // here
}


Daniel Yoen comments:

Note : after refreshing the page, you must remove the line(last code) from header.php or index.php

Matt comments:

I already have the taxonomy created since woocommerce creates them automatically, but it doesn't look like this worked.

I put the code in my header.php and reloaded the homepage, but none of the cp_additional_options values are showing up as terms in the Popular Features taxonomy.

Daniel Yoen comments:

replace with your own taxonomy name:

wp_insert_term($metaval, 'replace with your taxonomy name');

hope this help :-)

Matt comments:

The taxonomy name that you had in your example was correct (pa_popular-features), so I'm not sure what's going on.

I'm just supposed to copy and paste this within php tags within the header and then re-load the home page right?

Daniel Yoen comments:

The code should work (I've tried the code), unless we are in misunderstanding. lol :-)

could you add some screenshot of custom taxonomy(backend) to your question ? :-)

Best,
Daniel

Matt comments:

Alright here's a screenshot of the custom fields and where I'm trying to convert them to.

Hope this helps