Custom dynamic shipping rate cost calculation in Woocommerce - php

Question

I've set up a custom shipping method, i need to calculate shipping cost every time users get to the cart page.
It seems that woocommerce_package_rates action (where I calculate the custom shipping costs) runs only when user does click on a shipping method. This way the cart total is wrong most of the times, the worst is when the custom shipping method is already selected (user doesn't need to click it, so its cost doesn't update).
Is this the normal behavior of woocommerce_package_rates hook?
How to force woocommerce_package_rates to be always executed before displaying the cart totals?
EDIT
Here's some code i'm trying to hack with:
add_action( 'woocommerce_before_cart', 'force_shipping_calc', 1, 0 );
function force_shipping_calc() {
foreach( WC()->session->get('shipping_for_package_0')['rates'] as $rate_id =>$rate) {
// looking for the shipping method to recalc
if($rate->method_id == 'flat_rate') {
// mk1: set_shipping_total won't work, i'm using woocommerce < 3
//WC()->cart->set_shipping_total( MY_calculate_shipping() );
// mk2: doesn't work, "Indirect modification of overloaded property"
WC()->cart->totals['shipping_total'] = wc_format_decimal( MY_calculate_shipping(), wc_get_price_decimals() );
// mk3: cart total nor shipping total affected (?!)
WC()->cart->shipping_total = MY_calculate_shipping();
// mk4: ... ?! work in progress...
}
}
function MY_calculate_shipping() {
return 99.99;
}
add_filter( 'woocommerce_package_rates', 'fty_shipping_flat_rate_cost_calculation', 10, 2 );
function fty_shipping_flat_rate_cost_calculation($rates, $package) {
foreach($rates as $rate_key => $rate_values) {
$method_id = $rate_values->method_id;
$rate_id = $rate_values->id;
if ( 'flat_rate' === $method_id ){
$dist_cost = MY_calculate_shipping();
$price_excl_tax = $rates[$rate_id]->cost + $dist_cost;
$rates[$rate_id]->cost = number_format($price_excl_tax, 2);
$tax_keys = array_keys($rates[$rate_id]->taxes);
$price_excl_tax = $rates[$rate_id]->cost + $dist_cost;
$rates[$rate_id]->cost = number_format($price_excl_tax, 2);
$tax_calculation = $rates[$rate_id]->taxes[$tax_keys[0]] + $dist_cost*(TAX_AMOUNT_IVA-1);
$rates[$rate_id]->taxes[$tax_keys[0]] = number_format($tax_calculation, 2);
$rates[$rate_id]->cost += $dist_cost;
}
}
return $rates;
}
EDIT, again
This (mk. ~17786) seems to be in the right direction.
I changed the hook and force calculate_shipping() from WC_Shipping
add_action( 'woocommerce_cart_totals_before_shipping', 'fty_force_calculate_shipping', 1, 2550 );
function fty_force_calculate_shipping() {
WC()->shipping->calculate_shipping(WC()->shipping->packages);
WC()->cart->calculate_totals();
}
but it's not perfect yet, i think this hook makes a loop in the checkout page...

Answer 1

This needs to be done in woocommerce_package_rates only. In your code there is many errors or mistakes… Try the following:
function custom_calculated_shipping() {
return 99.99;
}
add_filter( 'woocommerce_package_rates', 'custom_shipping_rate_cost_calculation', 10, 2 );
function custom_shipping_rate_cost_calculation( $rates, $package ) {
foreach( $rates as $rate_key => $rate ) {
if ( 'flat_rate' === $rate->method_id ){
// Get rate cost and Custom cost
$initial_cost = $rates[$rate_key]->cost;
$additional_cost = custom_calculated_shipping();
// Calculation
$new_cost = $initial_cost + $additional_cost;
// Set Custom rate cost
$rates[$rate_key]->cost = round($new_cost, 2);
// Taxes rate cost (if enabled)
$new_taxes = array();
$has_taxes = false;
foreach ( $rate->taxes as $key => $tax ){
if( $tax > 0 ){
// Calculating the tax rate unit
$tax_rate = $tax / $initial_cost;
// Calculating the new tax cost
$new_tax_cost = $tax_rate * $new_cost;
// Save the calculated new tax rate cost in the array
$new_taxes[$key] = round( $new_tax_cost, 2 );
$has_taxes = true;
}
}
// Set new tax rates cost (if enabled)
if( $has_taxes )
$rate->taxes = $new_taxes;
}
}
return $rates;
}
Code goes in function.php file of your active child theme (or theme). Tested and works. It will work in all woocommerce versions since 2.6…
You should need to refresh the shipping caches:
1) First this code is already saved on your function.php file.
2) Empty cart.
3) In Shipping settings, enter in a Shipping Zone and disable a Shipping Method and "save". Then re-enable that Shipping Method and "save". You are done.