How to set and update dynamic Stock for similar product in WooCommerce

Question

Problem : I have 3 product similar type or they are same(Same product with different name). If those product should have same Stock. I am not sure it possible or not?

For example:

Product One Stock= 10
Product Two Stock= 10
Product Three Stock= 10

Goal: Want to set/update Same Stock for those product if any of them in order

Result 1: Product One qty 5 in order so new updated Stock

Product One Stock = 10-5 =5
Product Two Stock  = 10-5=5
Product Three Stock = 10-5=5

Result 2: Product One qty 5 and Product Two qty 2 in order So total qty of similar product =5+2=7 so new updated stock

Product One Stock = 10-7 =3
Product Two Stock = 10-7=3
Product Three Stock = 10-7=3

To Achieve this I set all similar product in a option like 12,45,133 (product ID) separated by comma ANd a option field for Common Quantity.

My Code what I am trying

add_action( 'woocommerce_thankyou', 'set_dynamic_quantity');
function set_dynamic_quantity_having_product_id_in_order($order_id){
    $order  = wc_get_order( $order_id );    
    $items = $order->get_items();
    //getting options value 
    $similar_product_options = get_option( 'similar_product_options_name' ); // Array of All Options
    $vpm_similar_product = $similar_product_options['vpm_similar_product']; //get similar product
    $vpm_similar_product_qty = $similar_product_options['vpm_similar_product_qty']; //get dynamic qty = 100


    $similar_id = explode( ",", $vpm_similar_product );


    //auto update qty if product in order 
    if(in_array( $order->get_items() , $similar_id )){
        foreach ( $items as $item => $value ) {
            $quantity = $item->get_quantity();
            $new_qty = $vpm_similar_product_qty - $quantity;
            //set new quantity to all similar product set in 
            $vpm_similar_product_qty['vpm_similar_product_qty'] = $new_qty;

            foreach ( $similar_id as $item_id => $item_data ) {
                update_meta_data( '_qty', $new_qty, $item_id );
                update_option('vpm_similar_product_qty',$same_type_product);
            }
        }
    }
}

Answer 1

I assume $vpm_similar_product_qty is a comma separated product IDs. I also assume that you update this value simply by update_option with the options array.

The logic presented here:

1. loop through the order items
2. for each order item, check if it is in the "twins" list
3. accumulate the ordered quantities
4. Reduce the total quantity from the synced quantity setting value
5. loop "twins" and update their quantity accordingly

This is an offered solution:

add_action( 'woocommerce_thankyou', 'set_dynamic_quantity_having_product_id_in_order');
function set_dynamic_quantity_having_product_id_in_order($order_id){
    $order  = new WC_Order( $order_id );

    # This protect from double reduction on the same order
    if (get_post_meta($order->get_id(), 'shared_products_quantities_updated', true)) return;


    $similar_product_options = get_option( 'similar_product_options_name' ); // Array of All Options
    $vpm_similar_product = $similar_product_options['vpm_similar_product']; //get similar product
    $shared_stock_products = explode( ",", $vpm_similar_product );

    // Local Testing $shared_stock_products = array(48, 45, 41);

    # First time, set stock level
    if (!get_option('vpm_similar_product_qty')) update_option('vpm_similar_product_qty', 100);

    # Get Shared stock level
    $vpm_similar_product_qty = get_option('vpm_similar_product_qty');

    # Count how many twin products bought
    $reduce_quantity = 0;
    foreach ($order->get_items() as $key => $item){
        if ( in_array($item['product_id'], $shared_stock_products ) ){
            $reduce_quantity += $item->get_quantity();
        }
    }

    # Sync stock levels according to the shared stock level setting
    $updated_quantity = $vpm_similar_product_qty - $reduce_quantity;
    foreach ($shared_stock_products as $product_id){
        $product = new WC_Product($product_id);
        $product->set_stock_quantity(  $updated_quantity );
        $product->save();
    }


    # Prevent duplicate qty deduction
    add_post_meta($order->get_id(), 'shared_products_quantities_updated', true);


    # Sync back the quantity to the shared quantity
    update_option('vpm_similar_product_qty', $updated_quantity);

}

There is one issue which you didn't cover though:

The shared stock is 10. Two "twin" products are in cart, one with qty of 8 and one with 5. This will produce a negative stock value. But since this issue is out of this scope, I will not address it.