group a field generates error fw core

[Dario]

I have this tag

@(Html.Kendo().Grid<Portale.Web2.Data.Entities.Contact>()
          .Name("contactGrid")
      .DataSource(dataSource => dataSource
          .Ajax()
          .Read(read => read.Action("GetContacts", "Contacts").Data("addInfo"))
       )
      .Columns(columns =>
      {
          columns.Bound(product => product.Date).Format("{0:dd/MM/yyyy}");
          columns.Bound(product => product.Name);
          columns.Bound(product => product.City);
          columns.Bound(product => product.SouceType);
          columns.Bound(product => product.Type);
          columns.Bound(product => product.Status);
          columns.Command(command => command.Custom("Completa").Visible("isNew").Click("completeContact"));
      })
      .Pageable(p =>
      {
          p.PageSizes(new[] { 5, 10, 30 });
          p.Info(true);
          p.Enabled(true);
      })
      .Sortable()
      .Groupable()
      .Filterable()

)
<script>
    function addInfo(e) {
        var statusFilter = $("#statusFilter").val();
     }
</script>

 

I call this action

 

public ActionResult GetContacts([DataSourceRequest]DataSourceRequest request, string status = "")
        {
            if (status != "")
            {
                var contacts = from rec in _context.Contacts
                               where rec.Status == status.ToContactStatus()
                               select rec;
                DataSourceResult result = contacts.ToDataSourceResult(request);
                return Json(result);
            }
            else
            {
                var contacts = from rec in _context.Contacts
                               select rec;
                DataSourceResult result = contacts.ToDataSourceResult(request);
                return Json(result);

 

If I try to set a group, it shows me this exception

System.InvalidOperationException
  HResult=0x80131509
  Messaggio=Processing of the LINQ expression '(GroupByShaperExpression:
KeySelector: (t.Source Type),
ElementSelector:(EntityShaperExpression:
    EntityType: Contact
    ValueBufferExpression:
        (ProjectionBindingExpression: EmptyProjectionMember)
    IsNullable: False
)
)' by 'RelationalProjectionBindingExpressionVisitor' failed. This may indicate either a bug or a limitation in EF Core.

 

I'm using a EF Core 3.1.4 that it connects to SQL Server 2018

 

[Alex Hajigeorgieva]

Hi, Dario,

This is a known breaking change that Microsoft introduces with EF 3.1 and one of the solutions is to call ToList() before calling the ToDataSourceResult() or ToDataSourceResultAsync() extension methods.

You can read more about it in this forum thread:

https://www.telerik.com/forums/todatasource-throws-exception-using-ef-core-3-0-with-groups

Kind Regards,
Alex Hajigeorgieva
Progress Telerik