linqkit predicatebuilder or and nested combined predicates
if (!string.IsNullOrEmpty(qsId))
{
// default false
var inner = PredicateBuilder.False<Product>();
// first or
inner = inner.Or (i =>
Regex.IsMatch(i.GetProperty("makeTag").Value.ToString(), "\\b" +
qsId + "\\b");
// second or
inner = inner.Or (i =>
string.IsNullOrEmpty(i.GetProperty("makeTag")).Value.ToString());
predicate = predicate.And(inner);
}