Based on Add an additional cost to flat rate shipping each 3 items in Woocommerce answer code, I have made some changes to add an additional cost to flat are shipping method each 2 items (instead of each 3 items) and only when there are exclusively items from a specific category (here "T-Shirts" category).
Here's my code attempt:
// add X amount to shipping for every 2 items added to the cart (flat rate only)
add_filter('woocommerce_package_rates', 'shipping_additional_cost_each_three_items', 100, 2);
function shipping_additional_cost_each_three_items( $rates, $package ){
if ( is_admin() && ! defined( 'DOING_AJAX' ) )
return $rates;
// HERE set your additional shipping cost
$additional_cost = 8.40;
$items_count = WC()->cart->get_cart_contents_count();
// Define/replace here your correct category slug (!)
$product_category = 't-shirts';
$prod_cat = false;
// Going through each item in cart to see if there is anyone of your category
foreach ( WC()->cart->get_cart() as $cart_item ) {
$product_id = $cart_item['product_id'];
if ( has_term( $product_category, 'product_cat', $product_id ) ){
$prod_cat = true;
}
}
// Loop through the shipping taxes array
foreach ( $rates as $rate_key => $rate ){
$has_taxes = false;
// Targetting "flat rate"
if( 'flat_rate' === $rate->method_id ){
// Get the initial cost
$initial_cost = $new_cost = $rates[$rate_key]->cost;
// Adding the additional cost if product in T-Shirt category after every 2 items (3, 6, 9 …)
if ( $prod_cat ) {
for($i = 0; $i <= $items_count; $i+=3){
$new_cost += $additional_cost;
}
}
// Set the new cost
$rates[$rate_key]->cost = $new_cost;
// Taxes rate cost (if enabled)
$taxes = [];
// Loop through the shipping taxes array (as they can be many)
foreach ($rates[$rate_key]->taxes as $key => $tax){
if( $rates[$rate_key]->taxes[$key] > 0 ){
// Get the initial tax cost
$initial_tax_cost = $new_tax_cost = $rates[$rate_key]->taxes[$key];
// Get the tax rate conversion
$tax_rate = $initial_tax_cost / $initial_cost;
// Set the new tax cost
$taxes[$key] = $new_cost * $tax_rate;
$has_taxes = true; // Enabling tax
}
}
}
if( $has_taxes )
$rates[$rate_key]->taxes = $taxes;
return $rates;
}
}
For "Flat rate" chosen shipping method, the code works just fine when items from "t-shirts" category are in the cart. But if there is an item that doesn't belongs to "t-shirt" category, the rate just disappears and shows the title with no amount.
Can someone tell me where I have to place the condition 'if category is X', to make that code functional?