My CPT taxonomy meta_fields not showing in Wordpress REST API - wordpress

Question

I added a custom meta field to my cpt taxonomy with "{$taxonomy}_add_form_fields".
So far it is working fine (add, edit and save) but I cant find this field in the API /wp-json/wp/v2/rest_base.
Is this a filter issue or do i "ADD" this field to the API?

Answer 1

... This answers a slightly different question than the one above ...
You need to enable the REST API where you defined the taxonomy.
Just add 'show_in_rest_api' => true
Something like this:
<?php
add_action( 'init', 'create_book_tax' );
function create_book_tax() {
register_taxonomy(
'genre',
'book',
array(
'label' => __( 'Genre' ),
'rewrite' => array( 'slug' => 'genre' ),
'hierarchical' => true,
'show_in_rest_api' => true // <-- Do This!
)
);
}
?>

Answer 2

You register the meta field calling register_term_meta, observe that using show_in_rest key not only set to true, but at least with an schema description, it is available both in queries to get the data, and to get the schema of that endpoint with OPTIONS method.
register_term_meta('replica', 'nice_field', [
'type' => 'string',
'description' => 'a nice description',
'single' => true,
'show_in_rest' => [
'schema' => [
'type' => 'string',
'format' => 'url',
'context' => ['view', 'edit'],
'readonly' => true,
]
],
]);
Using the schema key its currently documented only for non scalar types, but it's valid for scalar values too.

Answer 3

I had a similar issue. The answers here seem to point to the way to expose the taxonomy itself via the REST API, but not the custom fields created via ${taxonomy}_add_form_fields.
After some more research, I concluded that one should extend the REST API to modify the responses and explicitly add these custom taxonomy fields.
So, in my case, this was the solution:
// Add a custom field to the taxonomy form
function my_add_extra_fields_func()
{
$tpl = '
<div class="form-field form-required">
<label for="link">Field Label</label>
<input type="text" name="link" id="link" />
<p>Some help text</p>
</div>
';
echo $tpl;
}
add_action('taxonomySlug_add_form_fields', 'my_add_extra_fields_func');
// Save the custom field to database in the options table
function my_save_extra_fields_func($term_id)
{
$term_item = get_term($term_id, 'taxonomySlug');
$term_slug = $term_item->slug;
$link = sanitize_text_field($_POST['link']);
update_option('taxonomySlug_link_' . $term_slug, $link);
}
add_action('create_taxonomySlug', 'my_save_extra_fields_func');
/**
* This is the part that addresses the question
* of making the custom field visible in the API
*/
// Expose the taxonomy custom field via REST API
add_action( 'rest_api_init', function () {
register_rest_field( 'taxonomySlug', 'extra_fields', array(
'get_callback' => function( $term_as_arr ) {
$term_slug = $term_as_arr['slug'];
$link = get_option('taxonomySlug_link_' . $term_slug);
return $link;
})
);
});
* taxonomySlug = the slug of my taxonomy