c# Dictionary> order list by DateTime (nullable value)

Question

I have a Dictionary<DateTime, List<Item>>

    Dictionary<DateTime, List<Item>> result =
        myList
            .GroupBy(k => new DateTime(k.Created.Value.Year, k.Created.Value.Month, 1))
            .OrderByDescending(k => k.Key)
            .ToDictionary(k => k.Key, v => v.ToList());

This will take a List<Item> groups it per year/month, order it descending (newest first) then creates a dictionary out of it.

My Question is: how can I OrderByDescending also the List within the Dictionary based on the the DateTime nullable (newest first)?

See that : [link](http://stackoverflow.com/questions/8110324/how-to-sort-a-dictionary-by-key) — Mitat Koyuncu, Aug 22 '15 at 07:38
First should be newest, there are no null values although is a nullable property. There will always be a datetime value. — user2818430, Aug 22 '15 at 07:44

score 2 · Answer 1 · answered Aug 22 '15 at 07:38

I think I figured it out:

Dictionary<DateTime, List<Item>> result = myList.GroupBy(k => new DateTime(k.Created.Value.Year, k.Created.Value.Month, 1))
  .OrderByDescending(k => k.Key)
  .ToDictionary(k => k.Key, v => v.OrderByDescending(t => t.Published.GetValueOrDefault()).ToList());

score 1 · Answer 2 · answered Aug 22 '15 at 07:42

Try this:

Dictionary<DateTime, List<Item>> result =
    myList
        .GroupBy(k => new DateTime(k.Created.Value.Year, k.Created.Value.Month, 1))
        .OrderByDescending(k => k.Key)
        .ToDictionary(k => k.Key, v => v.OrderByDescending(x => x.Created).ToList());

c# Dictionary> order list by DateTime (nullable value)

2 Answers2