Search between Specific Times - sql

Question

I have a date field and 2 time fields(Start Time and End Time). I have to get Data from the date and entered in that date field and between Start and end times.
I am using Linq query.
result = result.Where(x => x.CreatedDate.ToLocalTime() > search.StartTime &&
x.CreatedDate.ToLocalTime() < search.EndTime);
I am using this but I am getting the following error.
LINQ to Entities does not recognize the method 'System.DateTime ToLocalTime()' method, and this method cannot be translated into a store expression
Please Help.

Answer 1

You can't use ToLocalTime() for Linq to Entities. Because it can't be translated to SQL. There is no equivalent to apply it.
So, why don't you convert your startTime and endTime by considering required time zone which is stored in the database. Opposite conversion should be like that;
//I use utc time to provide example.
//Convert your dates with required timezones which is stored in the database
var startTime = search.StartTime.ToUtcDateTime();
var endTime = search.EndTime.ToUtcDateTime();
result = result.Where(x => x.CreatedDate > startTime &&
x.CreatedDate < endTime);

Answer 2

As Panagiotis Kanavos pointed out there may be no equivalent argument. When you do have the correct type though you are essentially doing a conversion of one DateTime to another. Both the predicate values and the set should have their values preferably stored in the same TimeZone. Here is a simple console example to show what I mean.
public class TestData
{
public DateTime Dt { get; set; }
public TestData(DateTime dt)
{
Dt = dt;
}
public override string ToString() => Dt.ToString();
}
static void Main(string[] args)
{
var dt = new DateTime(2018, 1, 11);
var s = dt;
var e = dt.AddHours(3);
var dts = new List<TestData>();
for (int i = 0; i < 10; i++)
{
dts.Add(new TestData(dt.AddHours(i)));
}
Console.WriteLine("Dates as are");
dts.ForEach(Console.WriteLine);
Console.WriteLine(Environment.NewLine);
Console.WriteLine("Dates to local time are");
dts.ForEach(x => Console.WriteLine(x.Dt.ToLocalTime()));
Console.WriteLine(Environment.NewLine);
Console.WriteLine("searches are");
Console.WriteLine(s);
Console.WriteLine(e);
Console.WriteLine(Environment.NewLine);
Console.WriteLine("searches to local time are");
Console.WriteLine(s.ToLocalTime());
Console.WriteLine(e.ToLocalTime());
Console.WriteLine(Environment.NewLine);
Console.WriteLine("Weird results as one set is cast to local and other is not. Plus the cast is now performed on presentation");
dts.Where(x => x.Dt.ToLocalTime() >= s && x.Dt.ToLocalTime() <= e).ToList().ForEach(Console.WriteLine);
Console.WriteLine(Environment.NewLine);
Console.WriteLine("expected results as both are uniform");
dts.Where(x => x.Dt >= s && x.Dt <= e).ToList().ForEach(Console.WriteLine);
Console.ReadLine();
}
Since different posters on SO are in different timezone the second result set will vary. But essentially I am in PST in the US so I see times for the second set eight hours prior to my first. You generally in .NET perform operations of storage to be UTC if your application is going to be worldwide or even country wide. Then you just deal with DateTimes and would only do a conversion on the client end for presentation to a potential end user. But most of the time not in the logic for predicates.