I have a log file that contains date/time strings formatted like this:
2019/10/01 15:30
As you can see, the strings don't contain any timezone information. However, I do know the timezone that the time is represented within.
If I use this C# code on my own PC, which has its local timezone set correctly, the time is parsed as expected. I'm expecting to convert the local time to UTC for inserting into a database.
Time.ParseExact("2019/10/01 15:30", "yyyy/MM/dd HH:mm", provider, DateTimeStyles.AdjustToUniversal & DateTimeStyles.AssumeLocal);
However, if I run this code on one of my Docker hosts, which has its timezone set to UTC, the times are parsed as UTC. This makes sense, since on a Docker host using UTC AssumeLocal will be the same as UTC.
Simply applying a manual offset isn't sufficient due to daylight saving time. Also, some of these logs are historical and go back to prior to the DST change, so even using an algorithm would be complex and it seems like it's something that should already be solved (i.e. given a date and timezone, determine if it's in DST or not and then adjust to UTC accordingly)
What I want to be able to do is to explicitly specify the timezone for the timestamp and have the framework use both the given timezone and the actual date to properly convert the time to UTC. I've looked at this question and this question but they all seem to depend on the system itself being set to the timezone that you want to assume the date is in.
The second question does seem to start addressing the issue of assuming a known timezone, but then the responses just use GetUtcOffset on the parsed time to determine the amount of time to offset the time. This assumes that the time was already parsed in the desired timezone.
I believe what you're looking for is TimeZoneInfo.
Using TimeZoneInfo, you can get the information you need from TimeZoneInfo.FindSystemTimeZoneById.
Those Ids are based on the operating system, but as long as all of your containers are on Linux (as an example) you will be able to use that to get a UTC time for storage. You mention that you know what timezone your string is in, so you'll likely need something to convert that to Ids readable by TimeZoneInfo.
Code example taken from TimeZoneInfo.FindSystemTimeZoneById
using System;
public class Example
{
public static void Main()
{
// Get time in local time zone
DateTime thisTime = DateTime.Now;
Console.WriteLine("Time in {0} zone: {1}", TimeZoneInfo.Local.IsDaylightSavingTime(thisTime) ?
TimeZoneInfo.Local.DaylightName : TimeZoneInfo.Local.StandardName, thisTime);
Console.WriteLine(" UTC Time: {0}", TimeZoneInfo.ConvertTimeToUtc(thisTime, TimeZoneInfo.Local));
// Get Tokyo Standard Time zone
TimeZoneInfo tst = TimeZoneInfo.FindSystemTimeZoneById("Tokyo Standard Time");
DateTime tstTime = TimeZoneInfo.ConvertTime(thisTime, TimeZoneInfo.Local, tst);
Console.WriteLine("Time in {0} zone: {1}", tst.IsDaylightSavingTime(tstTime) ?
tst.DaylightName : tst.StandardName, tstTime);
Console.WriteLine(" UTC Time: {0}", TimeZoneInfo.ConvertTimeToUtc(tstTime, tst));
}
}
// The example displays output like the following when run on a system in the
// U.S. Pacific Standard Time zone:
// Time in Pacific Standard Time zone: 12/6/2013 10:57:51 AM
// UTC Time: 12/6/2013 6:57:51 PM
// Time in Tokyo Standard Time zone: 12/7/2013 3:57:51 AM
// UTC Time: 12/6/2013 6:57:51 PM
Related
Hi i receice some random datetimeoffset utc my point is
1 - turn it into chicago time
2- Define the chicago startOfDay
3-finaly convert chicago startOfDay back to an utc datetimeOffset.
(this process is needed to query an utc api)
i writed this that seem do what i want but realy not sure it will always do the job with day saving light etc..
someone can tell or improve the code?
var UTCDate = DateTimeOffset.UtcNow; //<----------Some random utc dateTimeOffset
TimeZoneInfo zone = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");
DateTimeOffset CSTDate = GetZoneDatetimeOffset(UTCDate, zone);
Console.WriteLine("Utc : {0} Chicago: {1} local : {2}", UTCDate, CSTDate, UTCDate.ToLocalTime());
Console.WriteLine(" Chicago StartOfDay: {0} Chicago StartOfDay To UTC : {1}", CSTDate.Date, CSTDate.Date.ToUniversalTime());
public DateTimeOffset GetZoneDatetimeOffset(DateTimeOffset someUTCDate , TimeZoneInfo destZone)
{
DateTimeOffset ZoneDateTimeOffset = TimeZoneInfo.ConvertTimeBySystemTimeZoneId(someUTCDate.DateTime , TimeZoneInfo.Utc.Id, destZone.Id);
return ZoneDateTimeOffset;
}
You have a few bugs in your code:
You call TimeZoneInfo.ConvertTimeBySystemTimeZoneId and pass a DateTime value. The result will thus also be a DateTime. The Kind of that result will be Unspecified. Assigning it to a DateTimeOffset thus will perform an implicit cast operation from DateTime to DateTimeOffset, which will use the computer's local time zone - not the time zone you are working with.
Both DateTimeOffset.Date and DateTimeOffset.DateTime also return a DateTime whose Kind is Unspecified. Thus when you call ToLocalTime or ToUniversalTime, you are again using your the computer's local time zone.
Determining the start of the day in a specific time zone can be tricky. Though it doesn't happen in Chicago (or anywhere in the USA), some time zones of the world have DST transitions that occur immediately at the start of the day. Thus 00:00 might not be the first moment of the day, or it might occur twice. Your code doesn't account for that.
A good example is Cuba, where DST next starts on 2022-03-13 at midnight, and thus the start of that day in Cuba is 2022-03-13T01:00.
You can use the GetStartOfDay method I already provided in this answer to handle these edge cases.
Putting it all together:
// Input values
DateTimeOffset utc = DateTimeOffset.UtcNow;
TimeZoneInfo zone = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");
// Convert with full fidelity using only DateTimeOffset values
DateTimeOffset converted = TimeZoneInfo.ConvertTime(utc, zone);
// Get the start of day using the method from https://stackoverflow.com/a/49988688
DateTimeOffset startOfDay = GetStartOfDay(converted.DateTime, zone);
// Output the results
Console.WriteLine("Original values:");
Console.WriteLine("Chicago: {0:o} UTC: {1:o} Local: {2:o}", converted, utc, utc.ToLocalTime());
Console.WriteLine();
Console.WriteLine("At start of day in Chicago:");
Console.WriteLine("Chicago: {0:o} UTC: {1:o} Local: {2:o}", startOfDay, startOfDay.ToUniversalTime(), startOfDay.ToLocalTime());
Example output (local time zone is US Pacific Time in this example):
Original values:
Chicago: 2022-03-10T10:58:47.8164830-06:00 UTC: 2022-03-10T16:58:47.8164830+00:00 Local: 2022-03-10T08:58:47.8164830-08:00
At start of day in Chicago:
Chicago: 2022-03-10T00:00:00.0000000-06:00 UTC: 2022-03-10T06:00:00.0000000+00:00 Local: 2022-03-09T22:00:00.0000000-08:00
See also the working .NET Fiddle here.
In c#, I do this
DateTime.Now.ToString("yyyy-dd-M--HH-mm-ss")
but it gets me the server time. However I also have the offset in this format for example "-04:00". How can I combine the offset to get the local time?
Thanks
If you mean that you want to get the server's system local time including offset, then use the DateTimeOffset.Now property. Then format it as desired.
DateTimeOffset.Now.ToString("yyyy-MM-dd HH:mm:ss zzz")
The zzz specifier produces the offset as a string in the ISO 8601 extended format, that you asked for.
If what you mean is you have a UTC offset from elsewhere and you want to apply it to the current UTC time from the server, then do the following instead:
TimeSpan offset = TimeSpan.Parse("-04:00");
DateTimeOffset now = DateTimeOffset.UtcNow.ToOffset(offset);
string result = now.ToString("yyyy-MM-dd HH:mm:ss zzz");
This takes the current server time, and applies the ToOffset function to adjust to the offset you provided.
Do keep in mind though that an offset is not the same as a time zone. The offset you have might be the one for the current date and time, or it might be for some other date and time in that time zone. For example, US Eastern Time is UTC-4 during daylight saving time, but UTC-5 during standard time. See "Time Zone != Offset" in the timezone tag wiki.
This worked.
DateTime.UtcNow.AddHours(DateTimeOffset.Parse("01/01/0001 00:00:00 -04:00").Offset.TotalHours).ToString("yyyy-dd-M--HH-mm-ss")
This should work
DateTime.UtcNow.AddHours(DateTimeOffset.Parse("01/01/0001 00:00:00 -04:00").Offset.TotalHours).ToString("yyyy-dd-M--HH-mm-ss",CultureInfo. InvariantCulture);
Need to add the directive
using System.Globalization;
I host my website (asp.net webforms, .Net 4.5, SQL Server 2012) on Godaddy and they (the server) use Mountain Standard Time (-7 compare to UTC time) which is never changed and does not observe daylight saving time.
So if I do
Response.Write("UTC Time: " + DateTime.UtcNow.ToString() + "<br/>");
Response.Write("Server Time: " + DateTime.Now.ToString() + "<br/>");
Response.Write("Server DateTimeOffset: " + DateTimeOffset.Now.ToString() + "<br/>");
It will display this:
UTC Time: 9/18/2015 5:14:09 PM
Server Time: 9/18/2015 10:14:09 AM
Server DateTimeOffset: 9/18/2015 10:14:09 AM -07:00
But my users are located in Atlanta, GA which does observe daylight saving time and according to timeanddate.com they use EDT in the summer and EST in the winter
How do I get correct current time of user? Let say user open my web-application and hit Show my time button, it will display a correct current user's time?
You should never rely on the time zone settings of a server. Therefore DateTime.Now should not be ever used in an ASP.NET application.
There are many other reasons to avoid DateTime.Now. Read:The case against DateTime.Now.
The local time of the server is never guaranteed to be the local time of the user of your website anyway. If it is, it's just coincidental.
The easiest way to get the user's current time in their time zone is via JavaScript:
var now = new Date();
Though this is based on the user's clock, which may or may not be correctly set. To have any guarantees about the time, you'd have to use the UTC time of the server's clock, with the user's time zone applied.
One approach you might consider is to send the UTC time of the server down to the client, then load that into JavaScript in the client to project it to their time zone:
// C#
string serverUtcTime = DateTime.UtcNow.ToString("o"); // "2015-09-18T17:53:15.6988370Z"
// JS
var now = new Date("2015-09-18T17:53:15.6988370Z");
Actually detecting the user's time zone is a hard problem that does not currently have a solution. Some may recommend new Date().getTimezoneOffset(), but that only gives you the current numeric offset, not the time zone. Offsets can change for DST, and many time zones use similar offsets. There are also complications for historical dates near DST transitions that will work against you.
Scripts like jsTimeZoneDetect can guess your IANA time zone ID, such as America/New_York for Eastern time, but they are not 100% accurate. If you need the user's time zone on your server, then ultimately should ask the user for their time zone somewhere in your application.
In .NET, you can use Noda Time to work with IANA time zones. Without Noda Time, .NET has the TimeZoneInfo class, but it can only work with Windows time zones.
If you know for certain that the users are in Atlanta, GA (which is in the US Eastern time zone), then you can do this:
DateTime utc = DateTime.UtcNow;
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
DateTime eastern = TimeZoneInfo.ConvertTimeFromUtc(utc, tz);
Or, with Noda Time and IANA time zone IDs:
Instant now = SystemClock.Instance.Now;
DateTimeZone tz = DateTimeZoneProviders.Tzdb["America/New_York"];
ZonedDateTime eastern = now.InZone(tz);
You can use TimeZoneInfo.ConvertTime to convert from one time zone to another. However, if you just convert to EST or EDT, it will always display that value. If you want to always display the correct time for the client, you'll need to do something like using Javascript to store the client browser's local time zone in a cookie, then use that value as the time zone to convert to.
It might be a little more streamlined to get UtcTime from the server and convert from that using TimeZoneInfo.ConvertTimeFromUtc, if you expect to do much of this. Basically the same process, though.
Take a look at this example. This is quite easy.
[Test, TestCase(1), TestCase(9)]
public void Test(int month)
{
var serverTime = new DateTime(2015, month, 18, 10, 14, 09);
// No Daylight saving in Russia
var serverTimeZone = TimeZoneInfo.FindSystemTimeZoneById("Russian Standard Time");
// Daylight saving in Atlanta
var localTimeZone = TimeZoneInfo.FindSystemTimeZoneById("Atlantic Standard Time");
// check if ConvertTime take care of daylight saving
var localTime = TimeZoneInfo.ConvertTime(serverTime, serverTimeZone, localTimeZone);
// it does
if (localTimeZone.IsDaylightSavingTime(localTime))
Assert.AreEqual(string.Format("{0}/18/15 04:14 AM", month), localTime.ToString("M/dd/yy hh:mm tt", System.Globalization.CultureInfo.InvariantCulture));
else
Assert.AreEqual(string.Format("{0}/18/15 03:14 AM", month), localTime.ToString("M/dd/yy hh:mm tt", System.Globalization.CultureInfo.InvariantCulture));
}
If daylight saving time is in effect, and a date object has been saved into the database (UTC format) which you retrieve to show it in the view (for example the view in asp.net-mvc).
And you do that by using this method:
public static DateTime ConvertToLocalTimeFromUtcTime(DateTime utcDate, string timeZoneId)
{
TimeZoneInfo localZone = TimeZoneInfo.FindSystemTimeZoneById(timeZoneId);
DateTime localTime = TimeZoneInfo.ConvertTimeFromUtc(utcDate, localZone);
if (localZone.IsDaylightSavingTime(localTime))
localTime = localTime.AddHours(1); // is this needed !?
return localTime;
}
The question is, does TimeZoneInfo.ConvertTimeFromUtc() handle DST's or do you have to check that yourself and either add or subtract X hour(s) to the date object?
Same question for when persisting a date object to the database by converting it to UTC format with ToUniversalTime().
Yes. ConvertTimeFromUtc will automatically handle daylight saving time adjustments, as long as the time zone that you are targeting uses daylight saving time.
From the MSDN documentation:
When performing the conversion, the ConvertTimeFromUtc method applies any adjustment rules in effect in the destinationTimeZone time zone.
You should not try to add an additional hour in your conversion. That will give you an incorrect translation.
Regarding DateTime.ToUniversalTime, it does take DST into account, but be careful with this method. It assumes that the input value is in the computer's local time zone. If you just need to mark it with DateTimeKind.Utc, then use DateTime.SpecifyKind instead.
I have this UTC+0 Date :
2011-11-28T07:21:41.000Z
and I'd like, on C#, convert it to a PST Date. How can I do it? Tried with :
object.Data.ToLocalTime()
but I can't get the correct value (which should be 2011-11-27)
EDIT
Also tried (after suggesion on another topic) this :
DateTime convertedDate = DateTime.SpecifyKind(
DateTime.Parse(object.Data.ToShortDateString()),
DateTimeKind.Utc);
DateTime dt = convertedDate.ToLocalTime();
string dataVideo = dt.ToShortDateString();
but the date still 28/11/2011, not 27/11/2011
I've changed my clock to use UTC-08:00 Pacific Time.
DateTime timestamp = DateTime.Parse("2011-11-28T07:21:41.000Z");
Console.WriteLine("UTC: " + timestamp.ToUniversalTime());
Console.WriteLine("PST: " + timestamp.ToLocalTime());
Output:
UTC: 28/11/2011 7:21:41
PST: 27/11/2011 23:21:41
Example with TimeZoneInfo
DateTime timestamp = DateTime.Parse("2011-11-28T07:21:41.000Z");
Console.WriteLine("UTC: " + timestamp.ToUniversalTime());
Console.WriteLine("GMT+1: " + timestamp.ToLocalTime());
Console.WriteLine("PST: " + TimeZoneInfo.ConvertTimeBySystemTimeZoneId(timestamp, "Pacific Standard Time"));
Output:
UTC: 28/11/2011 7:21:41
GMT+1: 28/11/2011 8:21:41
PST: 27/11/2011 23:21:41
For a little more color
2011-11-28T07:21:41.000Z
This is a ISO8601 Timestamp, the Z at the end stands for UTC. This represents a specific instance in time.
DateTime.Parse will return to you a local date time structure, there are three types of datetime kinds, UTC, Local, and Unspecified.
If you try displaying this, it will show you this instant in your computers current timezone (I'm eastern time so when I print it I get 11/28/2011 2:21:41 AM).
If I want to switch this DateTime Kind to UTC, I could do something like
DateTime.Parse("2011-11-28T07:21:41.000Z").ToUniversalTime()
Printing this now (since it's kind is now UTC) I get 11/28/2011 7:21:41 AM.
Note that although the time is printed differently both these date times are referring to the same instant in time.
To display this instant in a different timezone, the easiest way imo is the TimeZoneInfo class (though I'm not sure it's 100% accurate).
TimeZoneInfo.ConverTimeBySystemTimeZoneId(dateTime, "Pacific Standard Time").
Printing it now will yield your desired result 11/27/2011 11:21:41 PM
Note that this return DateTime's Kind property is now Unspecified, meaning you won't be able to transfer it back to UTC without more information. You no longer have a specific instant in time, rather you have a unspecified time..we know it's the same instant as the ones previously just in pacific time, but the computer no longer knows that. Keep that in mind if you want to store this time.