验证System.DateTime是UTC格式

Question

I have a requirement to store all of the dates recorded in database must be recorded as UTC. So far I can achieve this using Noda library with following method:

    public static DateTime NowUtc(string timeZoneId)
    {
        var timeZone = GetTimeZone(timeZoneId);
        var instant = SystemClock.Instance.Now;
        return instant.InZone(timeZone).ToDateTimeUtc();
    }

I'm going to validate every date that passed into data access layer must be in UTC format.

How do I achieve that?

Thanks

Note: I have created a custom class library that used Noda as the core engine and the output is converted back to System.DateTime.

Answer 1

I'm not completely sure what you are asking, but here are some tips:

• If all you need is "now" as a UTC DateTime , just use DateTime.UtcNow .

• If you are working with Noda Time instants and need a DateTime , just use instant.ToDateTimeUtc() . There's no point in working with time zones if you just need UTC.

• If you want to validate a DateTime is in UTC, then check the kind:

   dateTime.Kind == DateTimeKind.Utc 

• Your data layer will probably return DateTimeKind.Unspecified kinds of DateTime , so you would need to first specify the UTC kind before converting to a Noda Time Instant :

   DateTime dt = (DateTime) dataReader["YourDataField"]; DateTime utc = DateTime.SpecifyKind(dt, DateTimeKind.Utc); Instant instant = Instant.FromDateTimeUtc(utc); 

• Lastly, recognize that UTC isn't a format . It's a time scale. So a value can be "adjusted to UTC", or "of UTC kind", but it can't be "in UTC format".

Answer 2

Please go through http://msdn.microsoft.com/en-us/library/system.datetimeoffset.aspx

DateTimeOffset localServerTime = DateTimeOffset.Now;

DateTimeOffset utc = localServerTime.ToUniversalTime();

Console.WriteLine("UTC:{0}", utc);