Add a discount programmatically to an Order in Woocommerce 3.2+

Question

In woocommerce, we can add a discount to any order using Coupons feature (fixed amount, percent amount…).

Is it possible to add discount amount to any order programmatically where the discount amount can be any amount?

Any help will be appreciated.

Answer 1

The only available feature to make a discount programmatically for an Order, is tricking the Fee API. For info, this trick is not recommended by woocommerce, but used by many people as there is not a discount feature in Woocommerce outside Coupons.

The following function will allow you to make a fixed discount of any amount or a percentage discount. The order need to exist (to be saved before).

The function code (For Woocommerce versions 3.2+):

/**
 * Add a discount to an Orders programmatically
 * (Using the FEE API - A negative fee)
 *
 * @since  3.2.0
 * @param  int     $order_id  The order ID. Required.
 * @param  string  $title  The label name for the discount. Required.
 * @param  mixed   $amount  Fixed amount (float) or percentage based on the subtotal. Required.
 * @param  string  $tax_class  The tax Class. '' by default. Optional.
 */
function wc_order_add_discount( $order_id, $title, $amount, $tax_class = '' ) {
    $order    = wc_get_order($order_id);
    $subtotal = $order->get_subtotal();
    $item     = new WC_Order_Item_Fee();

    if ( strpos($amount, '%') !== false ) {
        $percentage = (float) str_replace( array('%', ' '), array('', ''), $amount );
        $percentage = $percentage > 100 ? -100 : -$percentage;
        $discount   = $percentage * $subtotal / 100;
    } else {
        $discount = (float) str_replace( ' ', '', $amount );
        $discount = $discount > $subtotal ? -$subtotal : -$discount;
    }

    $item->set_tax_class( $tax_class );
    $item->set_name( $title );
    $item->set_amount( $discount );
    $item->set_total( $discount );

    if ( '0' !== $item->get_tax_class() && 'taxable' === $item->get_tax_status() && wc_tax_enabled() ) {
        $tax_for   = array(
            'country'   => $order->get_shipping_country(),
            'state'     => $order->get_shipping_state(),
            'postcode'  => $order->get_shipping_postcode(),
            'city'      => $order->get_shipping_city(),
            'tax_class' => $item->get_tax_class(),
        );
        $tax_rates = WC_Tax::find_rates( $tax_for );
        $taxes     = WC_Tax::calc_tax( $item->get_total(), $tax_rates, false );
        print_pr($taxes);

        if ( method_exists( $item, 'get_subtotal' ) ) {
            $subtotal_taxes = WC_Tax::calc_tax( $item->get_subtotal(), $tax_rates, false );
            $item->set_taxes( array( 'total' => $taxes, 'subtotal' => $subtotal_taxes ) );
            $item->set_total_tax( array_sum($taxes) );
        } else {
            $item->set_taxes( array( 'total' => $taxes ) );
            $item->set_total_tax( array_sum($taxes) );
        }
        $has_taxes = true;
    } else {
        $item->set_taxes( false );
        $has_taxes = false;
    }
    $item->save();

    $order->add_item( $item );
    $order->calculate_totals( $has_taxes );
    $order->save();
}

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

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USAGE Examples:

1) Fixed discount of $12 (with a dynamic $order_id):

wc_order_add_discount( $order_id, __("Fixed discount"), 12 );

2) Percentage discount of 5% (with a dynamic $order_id):

wc_order_add_discount( $order_id, __("Discount (5%)"), '5%' );

The amount (or the percentage) can be also a dynamic variable…