Linq generation error (OrderBy/Skip/Take?)

[AlexFsmn]

Hello,
Im trying to port an old ASP.NET WebAPI project to .NET Core. (The code works with EF 6)
While doing so I encountered an error with one of my Linq-queries.
Im not really sure what SQL is generated from the query but it seems to be wrong since the error doesn't make any sense to me.

Models

public class Node
{
    public Node()
    {
        NodeRecords = new List<NodeRecord>();
    }
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public string Name { get; set; }
    public virtual List<NodeRecord> NodeRecords { get; set; }
}

public class NodeRecord
{
    [Key]
    public int NodeRecordId { get; set; }
    [Column("Node_Name")]
    [ForeignKey("Node_Name")]
    public string NodeName { get; set; }
    public int Change { get; set; }
}

 public class HighNode
{
    public string Name { get; set; }
    public int Change { get; set; }
}

Code

private List<HighNode> GetHighNodeDaysAgo(int days)
{
    List<HighNode> selection = new List<HighNode>();
    using (GameStatsDb db = new GameStatsDb())
    {
        selection = db.Nodes.Include(x => x.NodeRecords)
        .Select(s => new HighNode()
        {
            Name = s.Name,
            Change = s.NodeRecords.OrderByDescending(o => o.NodeRecordId).Skip(days).FirstOrDefault().Change
        }).OrderByDescending(t => t.Change).Take(100).ToList();
    }
    return selection;
}

Error Information:

An exception of type 'System.InvalidCastException' occurred in Microsoft.EntityFrameworkCore.dll but was not handled in user code

Additional information: Unable to cast object of type 'System.Int32' to type 'GameDbModels.NodeRecord'.

StackTrace

 at lambda_method(Closure , ValueBuffer )
   at System.Linq.Enumerable.SelectEnumerableIterator`2.MoveNext()
   at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at GameStatsServiceCrossPlatform.Controllers.NodeController.GetHighNodeDaysAgo(Int32 days) in ~\Controllers\NodeController.cs:line 82
   at GameStatsServiceCrossPlatform.Controllers.NodeController.GetTodaysHighNodes() in ~\Controllers\NodeController.cs:line 33
   at lambda_method(Closure , Object , Object[] )
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeActionFilterAsync>d__28.MoveNext()

Further technical details
Visual Studio version and tool:
Running Microsoft .NET Core Tools (Preview 2) in VS 2015 update 3
OS:
Windows 10
Framework versions:
"Microsoft.EntityFrameworkCore": "1.0.0",
"Microsoft.EntityFrameworkCore.Relational": "1.0.0",
"Microsoft.EntityFrameworkCore.SqlServer": "1.0.0",

Any idea what could be the issue?
I haven't seen that Take & Skip aren't supported yet and I have seen examples containing orderby.

[nourselim0]

I've faced this issue too, it seems to happen when doing Take or First on navigational properties.
I kept trying workarounds (changing the order of things in my query) and so on, and I wasn't able to pinpoint when it happens and when it doesn't happen. But even when this but didn't happen, the Take(1) or First didn't make it to the SQL Query and I got warning that EF failed to translate that part of the query.
After fighting this for hours I settled down for splitting the query into two parts (with the second part happening for every entry returned from the first part!), but I really hope this gets fixed soon!

[maumar]

Need to verify if this already fixed.

[maumar]

This is indeed fixed now. We generate the following query:

SELECT TOP(@__p_1) [x].[Name], (
    SELECT [o0].[Change]
    FROM [NodeRecords] AS [o0]
    WHERE [x].[Name] = [o0].[Node_Name]
    ORDER BY [o0].[NodeRecordId] DESC
    OFFSET @__days_0 ROWS FETCH NEXT 1 ROWS ONLY
)
FROM [Nodes] AS [x]
ORDER BY (
    SELECT [o].[Change]
    FROM [NodeRecords] AS [o]
    WHERE [x].[Name] = [o].[Node_Name]
    ORDER BY [o].[NodeRecordId] DESC
    OFFSET @__days_0 ROWS FETCH NEXT 1 ROWS ONLY
) DESC

[smitpatel]

As enhancement we should also alias the subquery.