DbArithmeticExpression arguments must have a numeric common type
Solution 1:
Arithmetic with DateTime
is not supported in Entity Framework 6 and earlier. You have to use DbFunctions*. So, for the first part of your statement, something like:
var sleeps = context.Sleeps(o =>
DbFunctions.DiffHours(o.ClientDateTimeStamp, clientDateTime) < 24);
Note that the DiffHours
method accepts Nullable<DateTime>
.
Entity Framwork core (when used with Sql Server, maybe other db providers) supports the DateTime AddXxx
functions (like AddHours
). They're translated into DATEADD
in SQL.
*EntityFunctions
prior to Entity Framework version 6.
Solution 2:
I know that this is an old question but in your specific case instead of using DBFunctions
as suggested by @GertArnold , couldn't you just invert the operation move out the arithmetic in question from the Lambda?
After all clientDateTime
and time24
are fix values so their difference does not need to be recalculated in every iteration.
Like:
TimeSpan time24 = new TimeSpan(24, 0, 0);
TimeSpan time18 = new TimeSpan(18, 0, 0);
var clientdtminus24 = clientDateTime - time24;
// first get today's sleeping hours
List<Model.Sleep> sleeps = context.Sleeps.Where(
o => (clientdtminus24 < o.ClientDateTimeStamp) &&
o.ClientDateTimeStamp.TimeOfDay > time18 &&
clientDateTime.TimeOfDay < time18 &&
o.UserID == userid).ToList();
This refactor is usually possible if you are trying to compare the stored datetime shifted by a fix timestamp with an other datetime.
Solution 3:
The other way, if performance is not the true goal, you can try using AsEnumerable()
.
So, it would be like
List<Model.Sleep> sleeps = context.Sleeps.AsEnumerable().Where(....
Adding AsEnumerable() will convert the SQL query to entity and allows to run .Net functions on them. For more info, check here about AsEnumerable