ASP.NET Core cannot sort grouped items - entity-framework

Question

I have the following model in my ASP.NET Core application:
public class LocationTypeGroup {
public string Name { get; set; }
public IEnumerable<LocationType> LocationTypes { get; set; }
}
public class LocationType
{
[Key]
public int LocationTypeID { get; set; }
public string Name { get; set; }
public string IntExt { get; set; }
}
I am trying to run a query that groups them by IntExt, and sorts by Name within each group.
The following works, but doesn't sort:
public async Task<List<LocationTypeGroup>> GetGroupedLocationTypes()
{
return await _context.LocationTypes
.GroupBy(p => p.IntExt)
.Select(g => new LocationTypeGroup
{
Name = g.Key,
LocationTypes = g.Select(x => x)
})
.OrderBy(x=>x.Name)
.ToListAsync();
}
If I change to this:
LocationTypes = g.Select(x => x).OrderBy(x => x)
Then I still do not get a sorted result.
What am I doing wrong?

Answer 1

It's possible that EF can't build SQL query.
So you need simplify it manually. and split to 2 queries:
var groups = await context.LocationTypes
.GroupBy(p => p.IntExt)
.ToListAsync();
return groups.Select(g => new LocationTypeGroup
{
Name = g.Key,
LocationTypes = g.Select(x => x)
})
.OrderBy(x=>x.Name);
The first query loads simply groups, and the second sorts them and converts to LocationTypeGroup.

Answer 2

May be it caused by too old version of Entity Framework Core. Try this approach, moreover it will be less expensive:
//data is loaded into memory
var data = await _context.LocationTypes.ToListAsync();
//data's transform
var answer = data.GroupBy(x => x.IntExt)
.Select(x => new LocationTypeGroup
{
Name = x.Key,
LocationTypes = x.AsEnumerable()
}).OrderBy(x => x.Name).ToList();