A more generic parameter checking:
<?php
/**
* Check if all required parameters are present in the request
*
* @param mixed $request any of $_GET, $_POST, $_REQUEST
* @param mixed $required array of required parameters
* @return bool true if all required parameters are present
*/
function check_params( array $request, array $required ): bool
{
$check = array_intersect( array_keys( $request ), $required );
return count( $check ) === count( $required );
}
?>
Use this like
<?php
if( !check_params( $_GET, ['cust_id','prod_id'] ) {
header( "HTTP/1.1 400 Bad Request" );
echo "Bad Request";
exit();
}
?>
Let me know if something is build in PHP already...