Linq group by and order by create date

Question

I have a list of messages in db like so:

FromLoginId, ToLoginId, Message, CreateDate

1, 2, "some message", 2/2/2010
1, 2, "one more", 2/3/2010
4, 2, "from 4 message", 3/4/2010
5, 2, "from 5 mess", 1/3/2010
5, 2, "newer 5", 3/2/2011

I need to have a list of messages grouped by FromLoginId ordered by createDate starting from the newest first.

EDIT: List of messages with the first newest message from the FromLoginId group.

so for example for loginid 2 I would get this result:

FromLoginId, ToLoginId, Message, CreateDate

5, 2, "newer 5", 3/2/2011
4, 2, "from 4 message", 3/4/2010
1, 2, "one more", 2/3/2010

please help. thanks

I think this has been answered here: http://stackoverflow.com/questions/755132/how-do-i-order-a-group-result-in-linq — Ucodia, Jun 28 '11 at 07:23

score 1 · Accepted Answer · edited Mar 08 '12 at 20:29

1

I think i figured it out. looks ok to me. can anyone please check it?

list.GroupBy(x => x.FromLoginId)
   .Select(x => x.OrderByDescending(y => y.CreateDate)
   .FirstOrDefault())
   .OrderByDescending(x => x.CreateDate)

edited Mar 08 '12 at 20:29

Justin Grant

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answered Jun 28 '11 at 07:24

ShaneKm

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score 0 · Answer 2 · answered Jun 28 '11 at 07:18

0

If you group by FromLoginId you can't display the messages themselves, only the count of them, or any aggregate function that might interest you.

answered Jun 28 '11 at 07:18

Variant

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Linq group by and order by create date

2 Answers2