Here it is an automated solution, that will do the job each time a variable product is called/browse by a customer.
The variable product will be updated with a default variation that has the highest price.
This will be done once only as I set a custom post meta key/value each time a variable product has been updated.
The code:
add_action( 'template_redirect', 'set_default_variation_job' );
function set_default_variation_job() {
if ( ! is_product() || is_admin() ) return;
global $wpdb, $post;
// Get an instance of the WC_Product object
$product = wc_get_product($post->ID);
$product_id = $post->ID;
// Check if default variation has been updated, if yes we exit
if( get_post_meta( $product_id, '_default_variation_updated', true ) ) return;
// Only for variable products
if ( $product->is_type( 'variable' ) ) {
$max_price = $product->get_variation_price('max', true); // Get Max variation price
// SQL Query: Get the variation ID of the max variation price
$result = $wpdb->get_col("
SELECT pm.post_id FROM {$wpdb->prefix}postmeta as pm
INNER JOIN {$wpdb->prefix}posts as p ON pm.post_id = p.ID
WHERE p.post_type LIKE 'product_variation' AND p.post_parent = $product_id
AND pm.meta_key LIKE '_price' and pm.meta_value = $max_price
");
$variation_id= reset($result); // get the first variation ID as a string
// Get an instance of the WC_Product_Variation object
$variation = wc_get_product($variation_id);
$default_attributes = array();
// Loop through this variation attributes and format them
foreach( $variation->get_variation_attributes() as $key => $value ){
$taxonomy = str_replace( 'attribute_', '', $key );
$default_attributes[ $taxonomy ] = $value;
}
// Set the default variation attributes in the Variable product
$product->set_default_attributes( $default_attributes );
// Set a meta data flag to avoid update repetitions
update_post_meta( $product_id, '_default_variation_updated', '1' );
$product->save(); // Save the data
}
}
Code goes in function.php file of your active child theme (active theme).
Tested and works.