Restrict Specific Product Quantity in Multiples of X on Cart and Before Checkout

restrict-specific-product-quantity.php

/**
 * @snippet       Restrict Specific Product Quantity in Multiples of X on Cart and Before Checkout
 * @link          https://www.techiesandesh.com/woocommerce-product-quantity-multiples-cart-page-checkout/
 * @author        Sandesh Jangam
 * @donate $50    https://www.paypal.me/SandeshJangam/50
 */
  

add_action( 'woocommerce_checkout_process', 'ts_minimum_order_item_count' );

function ts_minimum_order_item_count() {

	$multiples = 4;
	$total_products = 0;

	// Your product ids.
	$restrict_products = array( 17214, 19766, 19774, 19782 );

	foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {
		
		if ( in_array( $values['product_id'], $restrict_products ) ) {
			$total_products += $values['quantity'];
		}
	}

	if ( ( $total_products % $multiples ) > 0 ) {

		wc_add_notice( sprintf( __( 'Items can only be purchased in multiples of %s.', 'woocommerce'), $multiples ), 'error' );
	}
}

add_action( 'woocommerce_check_cart_items', 'ts_check_cart_quantities' );

function ts_check_cart_quantities() {
  	
  	if( ! is_cart() ) {
  		return;
  	}

	$multiples = 4;
	$total_products = 0;

	// Your product ids.
	$restrict_products = array( 17214, 19766, 19774, 19782 );

	foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {

		if ( in_array( $values['product_id'], $restrict_products ) ) {
			$total_products += $values['quantity'];
		}
		
	}

	if ( ( $total_products % $multiples ) > 0 ) {

		wc_add_notice( sprintf( __('You need to buy in quantities of %s products', 'woocommerce'), $multiples ), 'error' );
	}
}