Taxonomy ID by Post ID in custom endpoint - php

Question

I making custom endpoint for my custom post type. The one thing is the taxonomy ID. I need to get taxonomy ID by post ID. get_terms( 'gallery_tax', $post->ID ) gives me array with all taxonomy object
function wl_posts() {
$args = [
'numberposts' => 9999,
'post_type' => 'gallery',
];
$posts = get_posts($args);
$data = [];
$i = 0;
foreach ($posts as $post) {
$data[$i]['id'] = $post->ID;
$data[$i]['fimg_url'] = get_the_post_thumbnail_url($post->ID, 'large');
$data[$i]['proizvoditel'] = get_field('proizvoditel', $post->ID);
$data[$i]['tip'] = get_field('tip', $post->ID);
$data[$i]['razmer'] = get_field('razmer', $post->ID);
$data[$i]['forma'] = get_field('forma', $post->ID);
$data[$i]['rost'] = get_field('rost', $post->ID);
$data[$i]['ves'] = get_field('ves', $post->ID);
$data[$i]['ohvat'] = get_field('ohvat', $post->ID);
$data[$i]['vozrast'] = get_field('vozrast', $post->ID);
$data[$i]['galereya'] = get_field('galereya', $post->ID);
$data[$i]['taxonomy'] = get_terms( 'gallery_tax', $post->ID );
$i++;
}
return $data;
}
add_action('rest_api_init', function() {
register_rest_route('wl/v1', 'gallery', [
'methods' => 'GET',
'callback' => 'wl_posts',
]);
});

Answer 1

Using get_terms('gallery_tax') will give you all the terms in a taxonomy.
https://developer.wordpress.org/reference/functions/get_terms
You get all the existing terms in your taxonomy. So this is why you get the result.
Using get_the_terms($post->ID, 'gallery_tax') will give you all taxonomy terms attached to the post.
https://developer.wordpress.org/reference/functions/get_the_terms/
You get all the terms that have been assigned to your post.
If you want to display the name of the taxonomy itself and not display the terms associated with the post, you can first get all the names of the taxonomies outside of your post loop and then get the taxonomy name inside of your foreach:
...
$data = [];
$i = 0;
$taxnames = get_taxonomies('','names');
foreach ($posts as $post) {
...
$data[$i]['taxonomy'] = wp_get_post_terms($post->ID, $taxnames, array("fields" => "names"));
$i++;
}
...
https://developer.wordpress.org/reference/functions/get_taxonomies/