Make coupon field mandatory for a product category in WooCommerce

Question

I am trying to make it so the coupon field is mandatory on Woocommerce for a product category. I have tried to use the code from this answer but it only works with a set of coupon code. I need it to work with any valid coupon code.

Thank you for any help.

Answer 1

Try the following that will make the coupon field mandatory when a cart item from a specific product category is found:

add_action( 'woocommerce_check_cart_items', 'mandatory_coupon_code' );
function mandatory_coupon_code() {
     // Set your product categories in the array (can be term IDs, slugs or names)
    $product_categories = array( 'clothing' );

    $found = false;

    // Loop through cart items to check for the product categories
    foreach ( WC()->cart->get_cart() as $cart_item ){
        if( has_term( $product_categories, 'product_cat', $cart_item['product_id'] ) ){
            $found = true; // cart item from the product category is found
            break; // We can stop the loop
        }
    }

    // If not found we exit
    if( ! $found ) return; // exit

    $applied_coupons = WC()->cart->get_applied_coupons();

    // Coupon not applied and product category found
    if( is_array($applied_coupons) && sizeof($applied_coupons) == 0 ) {
        // Display an error notice preventing checkout
        $message = __( 'Please enter a coupon code to be able to checkout.', 'woocommerce' );
        wc_add_notice( $message, 'error' );
    }
}

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

Answer 2

Thought I'd share my version - it adds a required checkbox field so you can specify which coupons active this message. Used a combination of the solution posted here and this one.

// Add a custom checkbox to Admin coupon settings pages
add_action( 'woocommerce_coupon_options', 'add_coupon_option_checkbox', 10 );
function add_coupon_option_checkbox() {
    woocommerce_wp_checkbox( array(
        'id'            => 'items_mandatory',
        'label'         => __( 'Force specific items', 'woocommerce' ),
        'description'   => __( 'Make this coupon mandatory for specific items.', 'woocommerce' ),
        'desc_tip'      => false,
    ) );
}


// Save the custom checkbox value from Admin coupon settings pages
add_action( 'woocommerce_coupon_options_save', 'save_coupon_option_checkbox', 10, 2 );
function save_coupon_option_checkbox( $post_id, $coupon ) {
    update_post_meta( $post_id, 'items_mandatory', isset( $_POST['items_mandatory'] ) ? 'yes' : 'no' );
}


// Force Coupon codes for Woocommerce
add_action( 'woocommerce_check_cart_items', 'mandatory_coupon_code' );
function mandatory_coupon_code() {
     // Set your product categories in the array (can be term IDs, slugs or names)
    $product_categories = array( '58');
    $applied_coupons = WC()->cart->get_applied_coupons();
    $found = false;
    
    if( sizeof($applied_coupons) > 0 ) {
        // Loop through applied coupons
        foreach( $applied_coupons as $coupon_code ) {
            $coupon = new WC_Coupon( $coupon_code );
            if( $coupon->get_meta('items_mandatory') === 'yes' ) {
                $coupon_applied = true;
                break;
            }
        }
    }
    // Loop through cart items to check for the product categories
    foreach ( WC()->cart->get_cart() as $cart_item ){
        if( has_term( $product_categories, 'product_cat', $cart_item['product_id'] ) ){
            $found = true; // cart item from the product category is found
            break; // We can stop the loop
        }
    }

    // If not found we exit
    if( ! $found ) return; // exit
    
    // Coupon not applied and product category found
    
    if( ! $coupon_applied) {
        // Display an error notice preventing checkout
        $message = __( 'The product "%s" requires a coupon for checkout.' );
        wc_add_notice( sprintf($message, $cart_item['data']->get_name() ), 'error' );
    }
}