How can I generate SQL with WHERE statement in EFCore Query - entity-framework

Question

I am trying to write the EF Query with a filter and the generated SQL is not using WHERE statement on the SQL Server. It extracts all data and does the filter on the Client's Memory. I am quite worried about the performance and would like to apply the filter on the SQL Server.
The requirement is to count the number of records in an Hour time slot.
public async Task<int> GetNumberofSchedules(DateTime dt)
{
return await _context.Schedules.CountAsync(
s => s.state == 0
&& s.AppointmentDate.Value.Date == dt.Date
&& s.AppointmentTime.Value.Hours >= dt.Hour
&& s.AppointmentTime.Value.Hours < dt.AddHours(1).Hour
);
}
Sample Data
if given DateTime is 07/04/2017 08:20, it should return the number of records between 07/04/2017 08:00 and 07/04/2017 09:00
The count does return 6 which is correct but when I trace the generated SQL in SQL Profiler, it's retrieving all data.
Generated SQL in SQL Profiler
SELECT
[s].[EnrolmentRecordID], [s].[AF1], [s].[AcademicYearID], [s].[AdminName], [s].[AppForm], [s].[AppointmentDate],
[s].[AppointmentTime], [s].[BDT], [s].[BKSB], [s].[DateCreated],
[s].[DateModified], [s].[Employer], [s].[EmployerInvited],
[s].[EmployerReps], [s].[MIAPP], [s].[NI], [s].[ProposedQual],
[s].[SMT], [s].[StudentInvited], [s].[StudentName]
FROM
[dbo].[EN_Schedules] AS [s]
I would like to amend my EF code to generate WHERE statement and do the filter on the server side. How can I achieve it?
Update1:
If I remove filters for TimeSpan value, it generates the correct SQL statement as the following: So, it seems to me that I need to apply the filter differently for TimeSpan Field.
exec sp_executesql N'SELECT COUNT(*) FROM [dbo].[EN_Schedules] AS [s]
WHERE ([s].[state] = 0) AND (CONVERT(date, [s].[AppointmentDate]) =
#__dt_Date_0)',N'#__dt_Date_0 datetime2(7)',#__dt_Date_0='2017-04-07
00:00:00'
**Update2: **
By using Ivan's solution, I ended up doing like this:
var startTime = new TimeSpan(dt.Hour, 0, 0);
var endTime = new TimeSpan(dt.Hour + 1, 0, 0);
return await _context.Schedules.CountAsync(
s => s.state == 0
&& s.AppointmentDate.Value.Date == dt.Date
&& s.AppointmentTime.Value >= startTime
&& s.AppointmentTime.Value < endTime
);

Answer 1

It's indeed converted to client evaluation - looks like many TimeSpan operations are still not supported well by EF Core.
After a lot of trial and error, the only way currently you can make it translate to SQL is to prepare TimeSpan limits as variables and use them inside the query:
var startTime = new TimeSpan(dt.Hour, 0, 0);
var endTime = startTime + new TimeSpan(1, 0, 0);
return await _context.Schedules.CountAsync(
s => s.state == 0
&& s.AppointmentDate.Value.Date == dt.Date
&& s.AppointmentTime.Value >= startTime
&& s.AppointmentTime.Value < endTime
);

Answer 2

It looks like Client Evaluation is the reason.
Disable it with ConfigureWarnings call. It will give an exception if a LINQ statement cann't be translated to SQL:
public class FooContext : DbContext
{
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder
.UseSqlServer("foo_connstr")
.ConfigureWarnings(warnings => warnings.Throw(RelationalEventId.QueryClientEvaluationWarning));
}
}