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orderby not working before groupby in asp net

I want order all users, then grouped by GroupCode.
I cant query all data, Because the number of users is large.
And I have to use pagination (take,skip)
What's my bug?
public class User
{
public int Id { get; set; }
public int GroupCode { get; set; }
public DateTime CreatedDateTime { get; set; }
}
var query = _context.Users
.OrderByDescending(s => s.CreatedDateTime)
.GroupBy(s => s.GroupCode)
.Select(s => s.Key)
.Skip(skip)
.Take(take)
.ToListAsync()
The only solution that comes to my mind is to query all Users.OrderBy and then group them by GroupCode

Why am I unable to do a count after a GroupBy with LINQ

I have the following classes:
public class LogViews
{
public string DateYYMMDD { get; set; }
public string Mode { get; set; }
public int LearnViews { get; set; }
public int PracticeViews { get; set; }
public int QuizViews { get; set; }
}
public class Views2Model
{
public string DateYYMMDD { get; set; }
public int Devices { get; set; }
public int? LearnViews { get; set; }
public int? PracticeViews { get; set; }
public int? QuizViews { get; set; }
}
What I would like to do is to get a count when grouped by the date:
var ViewCount = CreateExcelFile.ListToDataTable(Views
.GroupBy(x => x.DateYYMMDD)
.OrderBy(g => g.Key)
.Select(g => new Views2Model
{
DateYYMMDD = $"20{g.Key.Substring(0, 2)}/{g.Key.Substring(2, 2)}/{g.Key.Substring(4, 2)}",
Devices = g.Count(),
LearnViews = g.LearnViews.Count(),
PracticeViews = g.PracticeViews.Count(),
QuizViews = g.QuizViews.Count(),
})
.ToList());
But I am getting errors for g.LearnViews, g.PracticeViews and g.QuizViews
GetViews.cs(36,36): Error CS1061: 'IGrouping<string, LogViews>' does not contain a definition for 'LearnViews' and no accessible extension method 'LearnViews' accepting a first argument of type 'IGrouping<string, LogViews>' could be found (are you missing a using directive or an assembly reference?) (CS1061) (Cosmos)
Can anyone give advice on what I am doing wrong?

You're treating a group as if it's a single record. In your select g represents a group. A single group object has a common Key, but it contains many "View" items. Therefore you need to Sum the individual record values for LearnViews, etc.
var ViewCount = CreateExcelFile.ListToDataTable(Views
.GroupBy(x => x.DateYYMMDD)
.OrderBy(g => g.Key)
.Select(g => new Views2Model
{
DateYYMMDD = $"20{g.Key.Substring(0, 2)}/{g.Key.Substring(2, 2)}/{g.Key.Substring(4, 2)}",
Devices = g.Count(),
LearnViews = g.Sum(gi => gi.LearnViews),
PracticeViews = g.Sum(gi => gi.PracticeViews),
QuizViews = g.Sum(gi => gi.QuizViews),
})
.ToList());

Maybe you've messed up using succesive LINQ function. g is not LogViews, but it's IEnumerable<LogViews>. As I see in your code, You used g.Count(), but there is no Count function defined in LogViews, right?

You can only do a Count() on an IEnumerable object.
LearnViews is an int.
What you want to do is : LearnViews = g.Sum(v => v.LearnViews)

.Nest Fluent Dsl Aggregations

I am using Elasticsearch .Nest.
I need to create a search query that will return fileProperties objects but only of the latest version of each fileProperties.
Each FileId have many versions. So what I need is to do a groupBy FileId and get the whole document object with the Max version for each FileId.
This my class:
public class FileProperties
{
public string FileName { get; set; }
public string FileId { get; set; }
public long? Version { get; set; }
public string FileType { get; set; }
public Dictionary<string,string> DynamicProperties { get; set; }
}
and my code:
var searchResponse = client.Search<FileProperties>(s => s.AllIndices().Size(100)
.Query(q =>
q.Match(m => m
.Field(f => f.FileName)
.Query(fileId))
&& q.Match(m => m
.Field(f => f.Version)
.Query(version))).Aggregations(fstAgg => fstAgg
.Terms("file", f => f
.Field(z => z.FileId.Suffix("keyword"))
.ExecutionHint(TermsAggregationExecutionHint.GlobalOrdinals)
.Aggregations(sums => sums
.Max("version", son => son
.Field(f4 => f4.Version )
)
)
) ) );
But the results only show the key and the max value for that key.
what I want is the full document object if that is possible...
Any ideas?

Getting a Dictionary from a Query with GroupBy

Given two persisted entities
public class Header
{
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual List<Detail> Details { get; set; }
}
and
public class Detail
{
public virtual int Id { get; set; }
public virtual Header MyHeader { get; set; }
public virtual string Text { get; set; }
public virtual object LotsOfPropertiesIDontNeed { get; set; }
}
I want to populate a new object
public class MiniHeader
{
public string Name { get; set; }
public Dictionary<int, string> DetailTexts { get; set; }
}
with only the name from the Header, and with a dictionary relating detail IDs to the associated texts. Note that Detail also has LotsOfPropertiesIDontNeed, which I would prefer not to pull
across the wire or even request from SQL Server.
With the code
IEnumerable<MiniHeader> mini =
ctx.Details.Include(d => d.MyHeader)
.GroupBy(d => d.MyHeader)
.Select(g => new MiniHeader()
{
Name = g.Key.Name,
DetailTexts = g.ToDictionary(d => d.Id, d => d.Text)
});
I get the expected
LINQ to Entities does not recognize the method 'System.Collections.Generic.Dictionary`2[System.Int32,System.String]
since .ToDictionary cannot execute on the database side. I can make it work like this:
IEnumerable<MiniHeader> mini =
ctx.Details.Include(d => d.MyHeader)
.GroupBy(d => d.MyHeader)
.AsEnumerable()
.Select(g => new MiniHeader()
{
Name = g.Key.Name,
DetailTexts = g.ToDictionary(d => d.Id, d => d.Text)
});
but I presume that LotsOfPropertiesIDontNeed will be requested of SQL Server and pulled across the wire.
Is there a way to make this work, without pulling the unnecessary fields?

You can project your results to an anonymous type and then apply AsEnumerable and later project to your class like:
IEnumerable<MiniHeader> mini =
ctx.Details.Include(d => d.MyHeader)
.GroupBy(d => d.MyHeader)
.Select(g => new
{
Name = g.Key.Name,
Details = g.Select(i => new { i.Id, i.Text }),
})
.AsEnumerable()
.Select(e => new MiniHeader()
{
Name = e.Name,
DetailTexts = e.Details.ToDictionary(d => d.Id, d => d.Text)
});
This will let you get only those field that you need and later you can use ToDictionary on an in-memory collection.

Select property of an object that is in a list of objects which is also in another list of objects

I have the next arhitecture:
public class Element
{
public uint Id { get; set; }
public ICollection<ElementDetails> elementDetails { get; set; }
}
public class ElementDetails
{
public string ElementTitle { get; set; }
public string Content { get; set; }
}
And there's List<Element> someList that contains hundreds of elements.
I'm trying to obtain a list of ElementTitle (strings) that contains a certain text (I've called it "seed").
What I want to accomplish it's a typeahead. Here is my attempt:
List<Element> suggestedElements = someList.Where(s => s.elementDetails.Any(ss => ss.ElementTitle.Contains(seed))).ToList();
List<string> suggestions = suggestedElements .SelectMany(t => t.elementDetails.Select(x => x.ElementTitle)).ToList() }); // contains all ElementTitle, including those ElementTitle that don't contain the "seed"...
How can I get rid of those elements that don't contain the seed?

List<string> suggestions = someList.SelectMany(x => x.elementDetails)
.Where(y => y.ElementTitle.Contains(seed))
.Select(z => z.ElementTitle)
.ToList();
Even simpler:
List<string> suggestions = someList.SelectMany(x => x.elementDetails)
.Select(y => y.ElementTitle);
.Where(z => z.Contains(seed))
.ToList();