如何在C＃中对像datatable这样的通用列表进行排序

Question

i working on c# project(winform).

on my project, i sorted a datatable like this:

dt.DefaultView.Sort = "a ASC, b ASC, c ASC";

now with below expression, i sorted a generic list, but results is different against datatale results.

var newList = oldList.OrderBy(x => x.a).OrderBy(x => x.b).OrderBy(x => x.c).ToList();

how can sorted my generic list like datatable results? (i want have same sort datatable results in generic list)

thanks.

Answer 1

Use ThenBy / ThenByDescending after first OrderBy / OrderByDescending operator - it performs subsequent ordering of already ordered sequence:

var newList = oldList.OrderBy(x => x.a)
                     .ThenBy(x => x.b)
                     .ThenBy(x => x.c)
                     .ToList();

Otherwise you are re-ordering full sequence each time by different value (ie you are introducing new primary ordering that ignores previous ordering - see Remarks section on MSDN). And you'll end up with sequence sorted only by value provided to last OrderBy call (property c in your case). Your current code is equivalent of

dt.DefaultView.Sort = "a ASC";
dt.DefaultView.Sort = "b ASC";
dt.DefaultView.Sort = "c ASC";