Hide conditionally Cart page coupon field in Woocommerce

Question

I want to hide the coupon field on the cart page for all products except for ones with a specific product category. I created the following code which works but every once in awhile which doesn't seem to be related to time, I get an error message showing up. It doesn't stop the code from working and doesn't appear to cause any issues. However, I can't seem to track down why I am getting the error message or how to solve it.

add_filter( 'woocommerce_coupons_enabled', 'wdc_hide_coupon_field_dinner_dances' );

function wdc_hide_coupon_field_dinner_dances($enabled){ 
$wdc_category = 'discount';
$has_cat = true;

foreach ( WC()->cart->get_cart() as $cart_item_key =>$cart_item ) {
   $wdc_product = $cart_item['data'];
   $product_id = method_exists( $wdc_product, 'get_id' ) ? $wdc_product->get_id() : $wdc_product->id;
   if ( has_term( $wdc_category, 'product_cat', $product_id ) ) $has_cat = false;
   }
   if ( $has_cat && is_cart() ) {
      $enabled = false;
  }
 return $enabled;
}

I get this error message

Error Details

=============
An error of type E_ERROR was caused in line 16 of the file /home/westviewdance/public_html/wp-content/plugins/WdcFreeTicketCoupon-for-Woocommerce/WdcFreeTicketCoupon for Woocommerce.php.
Error message: Uncaught Error: Call to a member function get_cart() on null in /home/westviewdance/public_html/wp-content/plugins/WdcFreeTicketCoupon-for-Woocommerce/WdcFreeTicketCoupon
for Woocommerce.php:16 Stack trace:
#0 /home/westviewdance/public_html/wp-includes/class-wp-hook.php(287): wdc_hide_coupon_field_dinner_dances(true)
#1 /home/westviewdance/public_html/wp-includes/plugin.php(206): WP_Hook->apply_filters(true, Array)
#2 /home/westviewdance/public_html/wp-content/plugins/woocommerce/includes/wc-coupon-functions.php(69): apply_filters('woocommerce_cou...', true)
#3 /home/westviewdance/public_html/wp-content/plugins/woocommerce/packages/woocommerce-blocks/src/Assets.php(157): wc_coupons_enabled()
#4 /home/westviewdance/public_html/wp-includes/class-wp-hook.php(287): Automattic\WooCommerce\Blocks\Assets::get_wc_block_data(Array)
#5 /home/westviewdance/public_html/wp-includes/plugin.php(206): WP_Hook->apply_filters(Array, Array)
#6 /home/westviewdance/public_html/wp-content/plugins/woocommerce/packages/woocommerce-

LoicTheAztec LoicTheAztec · Accepted Answer · 2020-08-05T15:22:41

Try the following simplified code with some conditions checks to avoid this error problem. Also when watching for product categories in cart items always use $cart_item['product_id'] as this way it will work for product variations too.

add_filter( 'woocommerce_coupons_enabled', 'hide_coupon_field_dinner_dances' );
function hide_coupon_field_dinner_dances( $enabled ){ 
    $cart = WC()->cart; // The WC_Cart Object
    
    // Only on cart page
    if( is_cart() && $cart && method_exists( $cart, 'get_cart' ) ) {
        $category = array('discount'); // <= Here define the product categories
        $enabled  = false; // Only enable when this product category is in cart
        
        // Loop through cart items
        foreach ( $cart->get_cart() as $cart_item ) {
            if ( has_term( $category, 'product_cat', $cart_item['product_id'] ) )  {
                $enabled = true;
                break;
            }
        }
    }
    return $enabled;
}

This should better works now avoiding the issue.

Hide conditionally Cart page coupon field in Woocommerce

Error Details

1 Answers