Auto add a product for cart item from specific product categories in WooCommerce

Question

I have a code to add a product (a deposit) automatically to a customers cart, no matter what product he has chosen - with the code below inside the functions.php. This works fine.

But now, how to extend the code that this product will only be automatically added to the cart when the customer has chosen a product from a specific product category? Eg the deposit shouldn't be added to the cart when a customer buys a gift card.

Thanks a lot!

/**
 * Automatically adds product to cart on visit
 */
add_action( 'template_redirect', 'add_product_to_cart' );
function add_product_to_cart() {
    if ( ! is_admin() ) {
        $product_id = 1267; //product added automatically
        $found = false;
        //check if product already in cart
        if ( sizeof( WC()->cart->get_cart() ) > 0 ) {
            foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {
                $_product = $values['data'];
                if ( $_product->get_id() == $product_id )
                    $found = true;
            }
            // if product not found, add it
            if ( ! $found )
                WC()->cart->add_to_cart( $product_id );
        } else {

        }
    }
}

Answer 1

You will have to use the Wordpress conditional function hast_term() in a completely different way.

The following code will auto add to cart a pre-defined product, if a product from a product category is already in cart:

add_action( 'woocommerce_before_calculate_totals', 'auto_add_item_based_on_product_category', 10, 1 );
function auto_add_item_based_on_product_category( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 )
        return;

    $required_categories = array('t-shirts'); // Required product category(ies)
    $added_product_id = 1267; // Specific product to be added automatically
    $matched_category = false;

    // Loop through cart items
    foreach ( $cart->get_cart() as $item_key => $item ) {
        // Check for product category
        if( has_term( $required_categories, 'product_cat', $item['product_id'] ) ) {
            $matched_category = true;
        }
        // Check if specific product is already auto added
        if( $item['data']->get_id() == $added_product_id ) {
            $saved_item_key = $item_key; // keep cart item key
        }
    }

    // If specific product is already auto added but without items from product category
    if ( isset($saved_item_key) && ! $matched_category ) {
        $cart->remove_cart_item( $saved_item_key ); // Remove specific product
    }
    // If there is an item from defined product category and specific product is not in cart
    elseif ( ! isset($saved_item_key) && $matched_category ) {
        $cart->add_to_cart( $added_product_id ); // Add specific product
    }
}

Code goes in functions.php file of your active child theme (or active theme). Tested and works.