[Plugin: WP ecommerce] Restrict product rating to logged in users

Hi all,

That’s probably a piece of cake for any developer but I am not proficient enough in php…

I am currently setting up wp ecommerce (using the mojo theme from splashingpiels) and found out that users that are not logged in can rate a product. Ideally only users that have bought a product should be able to rate it, however I want to keep it simple and only allow logged in users to rate the products.

WordPress provides the reference function if ( is_user_logged_in() that can be used to achieve the desired function. This will also involve:
1. an if/else statement
2. a smart copy/paste of the relevant parts of the code below
3. the insertion of a new message __( 'Sorry, you must be logged in to rate a product!', 'sp' ) to inform users.

if ( ! function_exists( 'sp_product_rate' ) )
{
	function sp_product_rate()
	{
		global $wpdb;
		$response = '';
		$nonce = $_POST['ajaxCustomNonce'];
		$rate = mysql_real_escape_string( trim( $_POST['rate'] ) );
		$id = mysql_real_escape_string( trim($_POST['id'] ) );
		$ip = $_SERVER['REMOTE_ADDR'];
		$current_time = time();
		if ( ! wp_verify_nonce( $nonce, 'ajax_custom_nonce' ) )
		{
			 die ( 'Busted!' );
		}
		$sql = "SELECT COUNT(id) FROM {$wpdb->prefix}wpsc_product_rating WHERE ipnum = '$ip' AND productid = '$id'";
		$get_result = $wpdb->get_var( $sql );
		if ( $get_result != 0 )
		{
			$sql = "SELECT AVG(rated) FROM {$wpdb->prefix}wpsc_product_rating WHERE productid = '$id'";
			$current_rating = $wpdb->get_var( $sql );
			$current_rating = floor( $current_rating );
			$response .= '<span class="star-rating-control">';
			for ( $i = 1; $i < 6; $i++ )
			{
				$checked = '';
				if ( $current_rating >= 1 )
				{
					$checked = 'star-rating-on';
				}
				$response .= '<div class="wpec-star-rating rater-0 star star-rating-applied star-rating-readonly ' . $checked . '">';
				$response .= '<a title="'.$i.'">'.$i.'</a></div>';
				$current_rating = $current_rating - 1;
			}

			$response .= '</span><p class="message">' . __( 'Sorry, you already rated!', 'sp' ) . '</p>';
			echo $response;
		}
		else
		{
			$sql = "INSERT INTO {$wpdb->prefix}wpsc_product_rating (ipnum,productid,rated,time) VALUES ('$ip','$id','$rate','$current_time')";
			$wpdb->query( $sql );
			$sql = "SELECT AVG(rated) FROM {$wpdb->prefix}wpsc_product_rating WHERE productid = '$id'";
			$current_rating = $wpdb->get_var( $sql );
			$current_rating = floor( $current_rating );
			$response .= '<span class="star-rating-control">';
			for ( $i = 1; $i < 6; $i++ )
			{

				$checked = '';
				if ($current_rating >= 1) {
					$checked = 'star-rating-on';
				}
				$response .= '<div class="wpec-star-rating rater-0 star star-rating-applied star-rating-readonly ' . $checked . '">';
				$response .= '<a title="'.$i.'">'.$i.'</a></div>';
				$current_rating = $current_rating - 1;
			}
				$response .= '</span><p class="message">' . __( 'Thanks for rating!', 'sp' ) . '</p>';
			echo $response;
		}
		exit;
	}
}