How to get product variations by product id woocommerce 5.x

To get Woocommerce product variations or attributes, we would have to pass product id first and a Woocommerce hook to implement.

If we would call it before some actions have finished like ( woocommerce_init, woocommerce_after_register_taxonomy, and woocommerce_after_register_post_type ) then it would throw an error.

Find product id in woocommerce

In Woocommerce there are many ways to get a product id.

global $product;
$id = $product->get_id();

if you are in WordPress Loop then use get_the_ID()

So to get product variations by product id we have to pass it to wc_get_product function. It will return WC_Product_Variable Object.

After getting WC_Product_Variable Object you can directly call get_available_variations() method to get all available variations of a product.

To find the Woocommerce product variation_id

Using wp_list_pluck( $variations, ‘variation_id’ ) we can get a array of variation_id.

complete code below

add_action('woocommerce_after_register_post_type', 'woo_product_variation');
function woo_product_variation(){
	/* global $product;
	$product_id = $product->get_id(); */
	
	/* woocommerce product object by product id */
	$product_id 	= 12;
	$product 		= wc_get_product($product_id);
	$variations 	= $product->get_available_variations();

	/* return variations id array */
	$variations_id 		= wp_list_pluck( $variations, 'variation_id' );
	/* return variation attributes array */
	$attributes 		= $product->get_variation_attributes();
	$attributesArray 	= wp_list_pluck( $variations, 'attributes' );

	foreach($attributesArray as $nameOfAttribute => $valueOfAttribute) {
		echo array_values($valueOfAttribute)[0];
	}
}

Easy to check if post has specific category.