EF导航属性包括不加载

Question

I am trying to access the Register navigational property on my RegisterCountLog .. For some reason it is always null. So when I try access RegisterName it is always null.

public IQueryable<RegisterCountLog> GetCountsForDevice(long deviceSerial)
{
    return this.ServiceCollection.GetAll(c => c.Register)
               .Where(c => c.DeviceSerial == deviceSerial).AsNoTracking();
}

Note that ServiceCollection.GetAll() will (or should) include the Register . The query after that specific bit aka queryableLogs is

SELECT 
    [Extent2].[Contribution] AS [Contribution], 
    [Extent1].[DeviceSerial] AS [DeviceSerial], 
    [Extent1].[LogEntryID] AS [LogEntryID], 
    [Extent1].[RegisterId] AS [RegisterId], 
    [Extent1].[Value] AS [Value], 
    [Extent1].[Timestamp] AS [Timestamp], 
    [Extent2].[RegisterId] AS [RegisterId1], 
    [Extent2].[DeviceSerial] AS [DeviceSerial1], 
    [Extent2].[RegisterName] AS [RegisterName], 
    [Extent2].[ZoneEntrance_ZoneEntranceID] AS [ZoneEntrance_ZoneEntranceID]
    FROM  [dbo].[RegisterCountLogs] AS [Extent1]
    INNER JOIN [dbo].[Registers] AS [Extent2] 
          ON  ([Extent1].[RegisterId] = [Extent2].[DeviceSerial]) 
          AND ([Extent1].[DeviceSerial] = [Extent2].[RegisterId])

Its used like so:

var queryableLogs = countLogService.GetCountsForDevice(serialNumber);
var groupedLogs= gLogs
    .Select(r => new Register
    {
        RegisterId = r.FirstOrDefault().RegisterId,
        RegisterName = r.FirstOrDefault().Register.RegisterName, // Here!
        DeviceSerial = r.FirstOrDefault().DeviceSerial,
        CountLogs = r.GroupBy(rc => 
                              new {Day = SqlFunctions
                                        .DatePart("dy", rc.Timestamp)})
                     .Select(rl => new RegisterCountLog()
                                   {
                                     Value = rl.to FirstOrDefault().Value,
                                     Timestamp = rl.FirstOrDefault()
                                                   .Timestamp,
                                   })
                     .OrderByDescending(l => l.Timestamp)
                     .ToList()
    })
    .Where(r=>r.CountLogs.Count() > 0)
    .OrderByDescending(r => r.RegisterId)
    .ToList();

Everything works perfectly except the RegisterName is always null. If I check out the query Register is null too. Why isnt it being loaded?

Here are the EF classes

public class RegisterCountLog
{
    [Key, Column(Order = 1)]
    [ForeignKey("Register")]
    public long DeviceSerial { get; set; }

    [Key, Column(Order = 2)]
    public long LogEntryID { get; set; }

    [Key, Column(Order = 3)]
    [ForeignKey("Register")]
    public long RegisterId { get; set; }

    public long Value { get; set; }

    public DateTime Timestamp { get; set; }

    public Register Register { get; set; }
}

public class Register
{
    public enum ContributionType
    {
        FlowIn,
        FlowOut
    }

    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    [Key, Column(Order = 1)]
    public long RegisterId { get; set; }

    [Key]
    [ForeignKey("Device"), Column(Order = 2)]
    public long DeviceSerial { get; set; }

    [StringLength(50)]
    public string RegisterName { get; set; }

    public ContributionType Contribution { get; set; }    

    public virtual Device Device { get; set; }
}

Answer 1

Probably you are using eager loading and you must specify .Include(x => x.Register) or .Include("Register") , depends on your EF version

If you named your variables great there can be another issue (eager loading isn't great with grouped things). One approach is to enumerate the query (to list) before selecting something. (if there aren't performance problems)

EDIT : as i read your previous comment, i really think is the group by issue ( group by changes your linq structure and include isn't working anympore )

Approach is this :

var groupedPersons     = db.Appointments
                        .Include_Service()
                        .Include_Location()
                        .Include_Room()
                        .IncludeEhr_Patient()
                        .IncludeEhr_Person()
                        .IncludeEhr_Personal()
                        .ToList() // see that i enumerate before i group by
                        .GroupBy(x => x.PersonId).Select()[.ToList()]