.NET Core 3.1 Linq 和 SQL 服务器无法转换 DateTime

Question

I have a project that is running on .NET Core 3.1 and has Entity Framework Core included.

My problem is I am trying to filter an object by a datetime field. The search term is a string and can be anything. The DateTime field is being displayed in the format yyyy-MM-dd so I believe that using that format in the ToString is appropriate.

Here is the code:

entitiesFromRepository = entitiesFromRepository.Where(m => m.DepartureDate.ToString("yyyy-MM-dd").Contains(searchTerm));

The entitiesFromRepository is an IQueryable .

The issue I believe is the ToString with a date format, as when I take the date format out it works.

Can anyone help here?

Answer 1

You can try TryParse your "search term"

    DateTime date;
    DateTime.TryParse("search term", out date);
    entitiesFromRepository = entitiesFromRepository.Where(m => m.DepartureDate.Date == date).ToList();

//this will work perfect if your "search term" comes as "2022-03-31" eg

Answer 2

It's not supported to use .ToString() on datetime but there is a trick that you can achieve your query like this:

entitiesFromRepository.Where(x => 
(x.DepartureDate.Year.ToString() 
+ "-" + 
x.DepartureDate.Month.ToString() 
+ "-" + 
x.DepartureDate.Day.ToString())
.Contains(searchTerm));

I've tested in .net 6 and works fine but I think it should work on .netcore 3.1 too.