Linq To Sql - Getting The Last Know History Entry For Each Divice, Prior To A Certain Date

I have a question similar to this entry: how-do-i-query-sql-for-a-latest-record-date-for-each-user ... but I need it in Linq. In short for the people who do not care to read the ot

Solution 1:

Something like this should work:

DateTime date = //... (e.g. 2016-01-05)

var result =
    entries //e.g., context.DeviceHistoryEntries
    .GroupBy(x => x.DeviceId)
    .Select(gr =>
        gr
        .Where(x => x.LastUpdatedDate < date)
        .OrderByDescending(x => x.LastUpdatedDate)
        .FirstOrDefault()) //This will give us null for devices that
                           //don't have a status entry before the date
    .AsEnumerable()
    .Where(x => x != null) //remove null values (optional)
    .ToList();