Add a calculated fee based on total after discounts in WooCommerce - php

Question

I'm trying to add a fee to my woocommerce cart based on the subtotal after discounts have been applied:
add_action( 'woocommerce_cart_calculate_fees','woocommerce_custom_surcharge' );
function woocommerce_custom_surcharge() {
global $woocommerce;
if ( is_admin() && ! defined( 'DOING_AJAX' ) )
return;
$percentage = 0.01;
$surcharge = $woocommerce->cart->subtotal - $woocommerce->cart->get_cart_discount_total();
$woocommerce->cart->add_fee( 'Surcharge', $surcharge, true, '' );
}
I don't believe calls like $woocommerce->cart->get_cart_discount_total() can be used in an action hook, which is why I keep getting 0.00 for the fee.
I also read around some WC values are deprecated and will always show zero, but it doesn't explain why those amounts appear in filters and not actions.
What else can I use in an action to get the same number and add a percent fee to?

Answer 1

The WC_Cart object argument is included in woocommerce_cart_calculate_fees action hook. I also use the percentage amount calculation, as I suppose you just forgot it in your code.
So you should try this instead:
add_action( 'woocommerce_cart_calculate_fees','wc_custom_surcharge', 10, 1 );
function wc_custom_surcharge( $cart ) {
if ( is_admin() && ! defined( 'DOING_AJAX' ) )
return;
// HERE set your percent rate
$percent = 1; // 1%
// Fee calculation
$fee = ( $cart->subtotal - $cart->get_cart_discount_total() ) * $percent / 100;
// Add the fee if it is bigger than O
if( $fee > 0 )
$cart->add_fee( __('Surcharge', 'woocommerce'), $fee, true );
}
Code goes in function.php file of your active child theme (or theme).
Tested and works perfectly.
Note: Also global $woocommerce; with $woocommerce->cart has been replaced by WC()->cart since a long time. The WC() woocommerce object already include itself global $woocommerce;…
Specific update:
add_action( 'woocommerce_cart_calculate_fees','wc_custom_surcharge', 10, 1 );
function wc_custom_surcharge( $cart ) {
if ( is_admin() && ! defined( 'DOING_AJAX' ) )
return;
// HERE set your percent rate and your state
$percent = 6;
$state = array('MI');
$coupon_total = $cart->get_discount_total();
// FEE calculation
$fee = ( $cart->subtotal - $coupon_total ) * $percent / 100;
if ( $fee > 0 && WC()->customer->get_shipping_state() == $state )
$cart->add_fee( __('Tax', 'woocommerce'), $fee, false);
}
Code goes in function.php file of your active child theme (or theme).
Tested and works.

Answer 2

the plugin i was using to create coupons was hooking into after_calculate_totals and adjusting the amount afterwards. anything that fires before the plugin wasn't counted into that adjusted total. i was able to call specific amounts using variables in the plugin to create the fee amount i needed
for anyone else who is interested: i am using the ignitewoo gift certificates pro plugin and wanted to create a fee based on the remaining balance after coupons. this is Loic's code with some modifications:
add_action( 'woocommerce_cart_calculate_fees','wc_custom_surcharge', 10, 1 );
function wc_custom_surcharge( $cart) {
global $woocommerce;
if ( is_admin() && ! defined( 'DOING_AJAX' ) )
return;
$state = array('MI');
// HERE set your percent rate
$percent = 6;
$coupTotal = 0;
foreach ( $woocommerce->cart->applied_coupons as $cc ) {
$coupon = new WC_Coupon( $cc );
$amount = ign_get_coupon_amount( $coupon );
$coupTotal += $amount;
}
// Fee calculation
$fee = ($cart->subtotal - $coupTotal) * $percent/100;
if (( $fee > 0 ) AND (in_array( WC()->customer->shipping_state, $state ) ))
$cart->add_fee( __('Tax', 'woocommerce'), $fee, false);
}