将DateTime与ASP.NET MVC和SQL Server进行比较

Question

I am trying to create a strongly-typed model and view. This portion of code is supposed to return a list of "emails" sent in a contact-us form.

I want to return all form submissions sent today. The SQL Server 2008 datatype is datetime . So I have a DateTime field in my model.

public ActionResult ResultTable()
{
    CombinedReport report = new CombinedReport();

    report.emails = report.db.ContactEmails.Where(w => w.FormInserted.Equals(DateTime.Today)).ToList();
    return PartialView(report);
}

When I ran this configured for the local built-in SQL Server CE, it worked fine.

When I set it up for our actual database running SQL Server 2008, it doesn't work.

With some trial-and-error, and looking at code in other parts of my program, I noticed that the C# implementation of DateTime is including 12:00:00AM as a part of the date, and when it's doing the comparison to SQL, it's sending that exact time in.

It won't let me compare a DateTime to a string, so I can't even format "today" as a string.

The CombinedReport model I instantiate here is just a view model for a specific page and doesn't directly map to a database ("ContactEmails" does).

What is the best way to go forward that will let me keep a strongly-type view and model?

Answer 1

If you only want to compare the date part of the value, you should make that explicit:

DateTime today = DateTime.Today;
report.emails = report.db.ContactEmails
                         .Where(w => w.FormInserted.Date == today)
                         .ToList();

Now whether the flavour of LINQ you're using supports the Date property is a different matter - but that's what I'd try to start with.

Answer 2

如果您使用的是EF，请使用EntityFunctions.TruncateTime方法：

.Where(w => EntityFunctions.TruncateTime(w.FormInserted).Equals(DateTime.Today))