T IQueryExecutor.ExecuteSingle <T>(QueryModel queryModel, bool returnDefaultWhenEmpty)
{
var isFirst = queryModel.ResultOperators.OfType <FirstResultOperator>().Any();
// TODO -- optimize by using Top 1
var cmd = BuildCommand <T>(queryModel);
var all = _runner.QueryJson(cmd).ToArray();
if (returnDefaultWhenEmpty && all.Length == 0)
{
return(default(T));
}
var data = isFirst ? all.First() : all.Single();
return(_serializer.FromJson <T>(data));
}