LINQ orderBy可能带有空值

Question

I have following code:

var ordered = allrows.OrderByDescending(n => int.Parse(n[SelectedScore].ToString()))
            .ThenByDescending(o => int.Parse(o[FirstSelected].ToString()))
            .ThenByDescending(o => int.Parse(o[SecondSelected8].ToString()))

However SelectedScore, FirstSelected, SecondSelected may be empty. I would like the order by to skip on empty ones.

So for example if FirstSelected is empty elements would be ordered first by SelectedScore then by SecondSelected.

Don't know how to do that in an elegant way.

Thanks in advance

Answer 1

SelectedScore , FirstSelected , and SecondSelected are all variables that do not depend on the the value of the row, so you can just make the order-by call depending on whether each value is set.

In order to have a common starting point (so you don't have to figure out which is the first set variable, to call OrderByDescending instead of ThenByDescending ), you can sort by a constant value first:

var ordered = allrows.OrderBy(x => 0);

if (!string.IsNullOrEmpty(SelectedScore))
    ordered = ordered.ThenByDescending(o => int.Parse(o[SelectedScore].ToString()));

if (!string.IsNullOrEmpty(FirstSelected))
    ordered = ordered.ThenByDescending(o => int.Parse(o[FirstSelected].ToString()));

if (!string.IsNullOrEmpty(SecondSelected))
    ordered = ordered.ThenByDescending(o => int.Parse(o[SecondSelected].ToString()));