Adding a promotional product when a certain cart amount is reached

I am looking for the right hook in WooCommerce because I need to add a promotional product to the cart when a certain cart amount of is reached, such as 100 conventional units.

I have also used the hook 'init' but I do not think it’s right.

Here is my code:

function add_free_product_to_cart(){
    global $woocommerce;
    $product_id = 2006; 
    $found = false;
    if ( sizeof( $woocommerce->cart->get_cart() ) > 0 ) 
    {
        foreach ( $woocommerce->cart->get_cart() as $cart_item_key => $values ) 
        {
            $_product = $values['data'];
            if ( $_product->id == $product_id )
            $found = true;
        }
        if(!$found)
        {
            $maximum = 100;
            $current = WC()->cart->subtotal;
            if($current > $maximum){
                $woocommerce->cart->add_to_cart( $product_id );
            }           
        }       
    }   
}
add_action( 'woocommerce_add_to_cart', 'add_free_product_to_cart' );

which hook I should use for that purpose?

Or could you give me a related link to to some similar problem?

Thanks

Answer

As you are targeting a certain cart amount to add a promotional product in the cart, you could use woocommerce_before_calculate_totals hook to achieve this with a custom built function.

You have also to remove that promo item if customer update the cart (which is embed in that custom function too).

Here is the code:

add_action( 'woocommerce_before_calculate_totals', 'adding_promotional_product', 10, 1 );
function adding_promotional_product( $cart ) {

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

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

    $promo_id = 99; // <=== <=== <=== Set HERE the ID of your promotional product
    $targeted_cart_subtotal = 100; // <=== Set HERE the target cart subtotal
    $has_promo = false;
    $subtotal = 0;

    if ( ! $cart->is_empty() ){

        // Iterating through each item in cart
        foreach ($cart->get_cart() as $item_key => $cart_item ){
            $product_id = version_compare( WC_VERSION, '3.0', '<' ) ? $cart_item['data']->id : $cart_item['data']->get_id();
            // If Promo product is in cart
            if( $product_id == $promo_id ) {
                $has_promo = true;
                $promo_key= $item_key;
            } else {
                // Adding subtotal item to global subtotal
                $subtotal += $cart_item['line_subtotal'];
            }
        }
        // If Promo product is NOT in cart and target subtotal reached, we add it.
        if( ! $has_promo && $subtotal >= $targeted_cart_subtotal ) {
            $cart->add_to_cart( $promo_id );
            // echo 'add';
        // If Promo product is in cart and target subtotal is not reached, we remove it.
        } elseif( $has_promo && $subtotal < $targeted_cart_subtotal ) {
            $cart->remove_cart_item( $promo_key );
        }
    }
}

This code goes on function.php file of your active child theme (or theme) or in any plugin file.

This code its tested and works.

Related thread: WooCommerce – Auto add or auto remove a freebie product from cart

Code updated on (2018-10-01)