Need to get total counts of a record from table in database using ASP.NET Core Web API - asp.net-core

Question

I need to count the total rows of a table when I pass a date as a parameter.
IService:
Task<int?> ScoresUpdated(DateTime date);
Service implementation:
public async Task<int?> ScoresUpdated(DateTime date)
{
var result = await _eventScheduleContext
.ViewPersonEventScore
.Where(x => x.DateTimeUtc.Date == date
&& x.ExamModeId == 1
&& x.EventStatusId == 8).ToListAsync();
return result.Count();
}
Controller:
public async Task<IActionResult> ScoresUpdated(DateTime date)
{
var result = await _examDetailService.ScoresUpdated(date);
return Ok(result);
}
But the output I'm getting is 0. In the database, I can see 80 rows.
Is there anything wrong with my code? Can you give me some suggestions how to fix it?

Answer 1

Suspect that it is due to this line
x.DateTimeUtc.Date == date
In SQL expression, I believe it translated to
CONVERT(date, DateTimeUtc) = #date
which #date is DateTime type. So this results that you are unable to query any records.
Use date.Date so that the translated SQL expression will be:
CONVERT(date, DateTimeUtc) = CONVERT(date, #date)
public async Task<int?> ScoresUpdated(DateTime date)
{
var result = await _eventScheduleContext
.ViewPersonEventScore
.Where(x => x.DateTimeUtc.Date == date.Date
&& x.ExamModeId == 1
&& x.EventStatusId == 8)
.ToListAsync();
return result.Count();
}
While seems you are only returning the count of the query result, you may consider applying CountAsync<TSource>(IQueryable<TSource>, CancellationToken).
This would improve the query performance as it will return the count, but not return all columns to the result.
public async Task<int?> ScoresUpdated(DateTime date)
{
return await _eventScheduleContext
.ViewPersonEventScore
.CountAsync(x => x.DateTimeUtc.Date == date.Date
&& x.ExamModeId == 1
&& x.EventStatusId == 8);
}

Answer 2

I don't see a reason for defining optional return type for the task (Task<int?>). I suggest using Task. refer to this Microsoft documentation for further details.
However, despite having 80 rows or entries in the DB as mentioned, you need to check which one of them match the condition you have defined (Where(x => x.DateTimeUtc.Date == date.Date
&& x.ExamModeId == 1
&& x.EventStatusId == 8))
If no entry meets the condition, the count of course would be zero.
Try removing the condition and check.