ChromeOrange · March 14, 2014 23:33 · Mar 14, 2014
diff --git a/gistfile1.php b/gistfile1.php
@@ -0,0 +1,35 @@
+/**
+ * Deactivate Flat Rate Shipping if products with specific shipping 
+ * classes are in the cart
+ *
+ * Add the shipping class slugs to the $shippingclass_array array
+ */
+add_filter( 'woocommerce_shipping_flat_rate_is_available', 'unset_woocommerce_shipping_methods_flat_rate', 10 ,2 );
+function unset_woocommerce_shipping_methods_flat_rate ( $return, $package ) {
+
+	// Setup an array of shipping classes that do not allow Flat Rate Shipping
+	$shippingclass_array = array( 'pickup-only' );
+
+	// loop through the cart checking the shipping classes
+	foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {
+
+		$shipping_class = get_the_terms( $values['product_id'], 'product_shipping_class' );
+
+		if ( isset( $shipping_class[0]->slug ) && in_array( $shipping_class[0]->slug, $shippingclass_array ) ) {
+			/**
+			 * If a product in the cart has a shipping class that does not allow for Flat Rate Shipping
+			 * then return false to unset the Flat Rate shipping method and break, no need to carry on
+			 */
+			return false;
+			break;
+		}
+
+	}
+
+	/**
+	 * It we make it this far then 
+	 * Flat Rate must be available, return true
+	 */
+	return true;
+
+}