WooCommerce - adding object terms not working properly - wordpress

Question

I'm using the following code to add attributes with terms:
$taxonomy = 'pa_' . $attr['name']; // The attribute taxonomy
if (!taxonomy_exists($taxonomy)) {
global $wpdb;
$insert = $wpdb->insert(
$wpdb->prefix . 'woocommerce_attribute_taxonomies',
array(
'attribute_name' => $attr['name'],
'attribute_label' => $attr['name'],
'attribute_public' => 0
),
array('%s', '%s', '%d')
);
if (is_wp_error($insert)) {
throw new WC_API_Exception('woocommerce_api_cannot_create_product_attribute', $insert->get_error_message(), 400);
}
// Clear transients
delete_transient('wc_attribute_taxonomies');
}
if (!term_exists($attr['value'], $attr['name'])) {
wp_insert_term($attr['value'], $attr['name']);
}
$term_slug = get_term_by('name', $attr['value'], $attr['name'])->slug; // Get the term slug
wp_set_post_terms($product_id, $attr['value'], $attr['name'], true);
// Set/save the attribute data in the product variation
update_post_meta($variation_id, 'attribute_' . $taxonomy, $term_slug);
// Assign to the product
wp_set_object_terms($product_id, $attr['value'], $taxonomy, true);
$att = array($taxonomy => array(
'name' => $taxonomy,
'value' => $attr['value'],
'is_visible' => '1',
'is_variation' => '1',
'is_taxonomy' => '1',
));
update_post_meta($product_id, '_product_attributes', $att);
However, the first time the code runs it adds the attributes without terms. If I run it a second time, only then does it add the terms to the previously added attributes.
Why is that?
Edit: The problem seems to start at the following line:
$term_slug = get_term_by('name', $attr['value'], $attr['name'])->slug
It simply doesn't yet recognize the newly created taxonomy. Only at the next run.
But why? Is there a function that can be used to "refresh" the attributes, or the $wp_attributes variable, which seems to be closely related?
Thanks!

Answer 1

It is hard to debug without looking at the live site. However, I think it could be something to do with this code:
if (!term_exists($attr['value'], $attr['name'])) {
wp_insert_term($attr['value'], $attr['name']);
}
On first request the term is inserted yet it will not be part of WordPress main query until further requests.
Again, this is mostly guessing as I need to see the actual implementation.

Answer 2

I use such a method to create a taxonomy.
public function setAttribute($attributeArgs)
{
$attributeId = wc_attribute_taxonomy_id_by_name($attributeArgs['slug']);
if ($attributeId === 0) {
$attributeId = wc_create_attribute($attributeArgs);
register_taxonomy('pa_' . $attributeArgs['slug'], ['product'], []);
} else {
$attributeId = wc_update_attribute($attributeId, $attributeArgs);
}
return [
'id' => $attributeId,
'args' => $attributeArgs,
];
}
An important line in this code is register_taxonomy('pa_' . $attributeArgs['slug'], ['product'], []);
Without this line, I had the same problem.