WooCommerce按重量计算运费及免运费类失效问题求助

Let's fix your free shipping class issue while honoring your core rule: if there's at least one paid shipping item in the cart, weight-based rates apply; only when all items are free shipping do we show the free option.

The Problem with Your Original Code #

Your current code only checks the total cart weight, but it doesn't account for the free_shipping class on individual products. It always hides the free shipping option whenever the weight falls into either tier, which is why the free shipping class never triggers.

Fixed Code #

Replace your existing custom_tiered_shipping_rates function with this updated version:

add_filter( 'woocommerce_package_rates', 'custom_tiered_shipping_rates_with_free_class', 9999, 2 );
function custom_tiered_shipping_rates_with_free_class( $rates, $package ) {
    // Check if any item in the cart requires paid shipping (not free_shipping class)
    $has_paid_shipping_items = false;
    foreach ( $package['contents'] as $item ) {
        $product = $item['data'];
        $shipping_class_slug = $product->get_shipping_class();
        
        // Flip the flag if we find a non-free-shipping item
        if ( $shipping_class_slug !== 'free_shipping' ) {
            $has_paid_shipping_items = true;
            break;
        }
    }

    // Scenario 1: Cart has paid shipping items – use weight-based rates
    if ( $has_paid_shipping_items ) {
        $total_weight = WC()->cart->get_cart_contents_weight();
        
        // Show only <19kg rate if weight is under 19kg
        if ( $total_weight < 19 ) {
            if ( isset( $rates['flat_rate:21'] ) ) {
                unset( $rates['flat_rate:22'], $rates['flat_rate:24'] );
            }
        }
        // Show only >19kg rate if weight exceeds 19kg (matches your original $300 rule)
        elseif ( $total_weight > 19 ) {
            if ( isset( $rates['flat_rate:22'] ) ) {
                unset( $rates['flat_rate:21'], $rates['flat_rate:24'] );
            }
        }
        // Optional: Handle exact 19kg (adjust if you want a specific rate here)
        else {
            unset( $rates['flat_rate:21'], $rates['flat_rate:22'] );
        }
    } 
    // Scenario 2: All items are free shipping – only show free option
    else {
        if ( isset( $rates['flat_rate:24'] ) ) {
            unset( $rates['flat_rate:21'], $rates['flat_rate:22'] );
        }
    }

    return $rates;
}

Key Changes Explained #

1. Paid Shipping Check: We loop through every item in the cart to check if any product doesn't have the free_shipping class. If so, we stick strictly to weight-based pricing.
2. Free Shipping Only for All-Free Carts: Only when every single item is marked with free_shipping do we hide the paid rates and show the free shipping option.
3. Weight Rule Alignment: I adjusted the weight check to >19 to match your original rule (over 19kg = $300). If you meant to use 20kg as the threshold, just change that value to >20.

Important Checks to Ensure It Works #

• Verify Shipping Class Slug: Go to WooCommerce > Products > Shipping Classes and confirm your free shipping class has the slug free_shipping. If it's different, update the value in the code.
• Confirm Rate IDs: Double-check that flat_rate:21, flat_rate:22, and flat_rate:24 match the actual IDs of your shipping methods. You can find these by editing a shipping method and looking at the URL (look for the rate_id parameter).
• Clear WooCommerce Cache: After adding the code, go to WooCommerce > Settings > Shipping, make a tiny change (like toggling a setting off/on), and save. This clears the shipping rate cache so your new rules take effect.

内容的提问来源于stack exchange，提问作者Victor S.