I'm consuming a Microsoft API which returns DateTimeOffset. The property has following documentation- This value is calculated based on current UTC time measured locally.
I want to compare this time with local server where my application is hosted. (So the DateTimeOffset is returned by Microsoft API and the place where I want to compare is on my server. These 2 can have different time zones).
When inspecting DateTimeOffset, Date & UTC property has same Date & Time and the Kind property is unspecified.
I'm currently using DateTimeOffset < DateTime.UtcNow for checking condition. Am I doing right?
You should use dateTimeOffset.LocalDateTime < dateTime.
.LocalDateTime method will convert the DateTimeOffset into your local time zone (with DateTimeKind.Local), so you can safely compare with your local DateTime.
You can get the offset time difference in the minutes using the below code
// Get the GMT time difference offset (This is your local time offset difference)
var timeOffsetinMiniut = DateTimeOffset.Now.Offset.TotalMinutes;
Now you can use add this offset in you local time to make it a UTC time.
var myNewDateTime = System.DateTime.Now.AddMinutes(timeOffsetinMiniut)
Now you can compare both time utc time and your new server time.
myNewDateTime < DateTime.UtcNow
Hope this will help you.
Thanks
Related
I use this code to convert my UTC string Time with format "yyyy-MM-ddTHH:mm:ssZ" to date time . for example :
string PurchaseDate == "2017-12-12T14:29:26Z";
datetime dt = DateTime.ParseExact(PurchaseDate , "yyyy-MM-ddTHH:mm:ssZ", null);
i know that PurchaseDate time is UTC time (because of "Z"). dt return {12/12/2017 5:59:26 PM} that it is my local Time(client time zone). in other word DateTime.ParseExact convert PurchaseDate to my client time zone! my question is how this method know my client TimeZone ? is it recommend to use this for global application and show user time zone at all ??
Update My question:
sometime for implement timezone management in my global website i google it for possible souloution and I find this Use ful link :
How to display dates and times in clients timezone
after month i found we can use TimeZoneInfo.Local for finding cliend TimeZone !
so should i say that link is useless? I want to know if there is a simple way to find client time zone in dotNet BackEnd code so why this complex way is Used ??
... how this method know my client TimeZone?
It doesn't understand anything about a "client". It just has the local time of wherever the code is running. If the code is running on a user's desktop computer or mobile device, then it's the time zone of that device.
If the code is running on a server, then it uses the time zone of the server. You should avoid this in general, as the server's time zone is usually irrelevant to your application or users. This applies to TimeZoneInfo.Local as well.
If you want to parse your string as UTC DateTime, then you'll need to pass an argument that tells the parser not to convert to local time:
string PurchaseDate = "2017-12-12T14:29:26Z";
DateTime dt = DateTime.ParseExact(PurchaseDate, "yyyy-MM-ddTHH:mm:ssK",
CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind);
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("...you'll need to decide...");
DateTime clientDateTime = TimeZoneInfo.ConvertTimeFromUtc(dt, tz);
In the above, I use DateTimeStyles.RoundtripKind, which says to evaluate the string for it's offset (Z in this case) and decide whether to use Utc, Local, or Unspecified kind on the resulting DateTime. Also note that you should use K in the format string, not Z.
A better approach would be to use DateTimeOffset instead of DateTime, in which case the Z will automatically set an offset of +00:00.
You'll still need to figure out what time zone to convert to, regardless of which approach you take. If you happen to be writing code that runs on the user's device, then you get the benefit of having TimeZoneInfo.Local predetermined for you. Otherwise you do not.
I am trying to figure out the best way of letting the users set the internal DateTime value of the Portable Class Library based on some string parameter they provide. The string parameter has to be a simple format.
So, now I have some considerations.
Is specifying UTC Offset enough for getting the right DateTime
public static DateTime FromUtcOffset(string value)
{
var utcDateTime = DateTime.UtcNow;
var offSet = TimeSpan.Parse(value);
return utcDateTime + offSet;
}
Or is specifying the TimeZone has some advantage over UTC Offset
TimeZoneInfo someTimeZone = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time");
DateTime convertTimeFromUtc = TimeZoneInfo.ConvertTimeFromUtc(utcDateTime, someTimeZone);
My question is: What would be the right string parameter that can be taken from the user to let him decide what the value of DateTime would be?
Utc Offset
TimeZone
Or any other alternative that's less verbose.
Actually, it depends:
Do you work with network hosts, located in different time zones
Do you store time values for using them in future
Does your library work locally (hence, knows user's timezone)
1+2 basically mean if your time offset might change. If it not (the library is intended for local use only), get local time and don't care about the time offset. However, if the offset might change, usually storing "absolute" time in UTC format should be enough. To do this, you can:
Ask user for UTC time, not their local time
or
Ask for local time + offset (or get the offset from the local time zone, if possible)
Convert it to UTC time and store/process in UTC time
Provide output using local time (using the offset from 1. if it didn't change)
In 1 and 3 you will need a timezone to figure out the time offset. You don't need to know timezone if you already know the offset. Moreover, DateTime itself can store time offset information. It also can tell you if it stores local or UTC time (see DateTime.Kind Property).
Quartz.net offers a method to get the next time of the next trigger event: http://quartznet.sourceforge.net/apidoc/1.0/html/html/cc03bb79-c0c4-6d84-3d05-a17f59727c98.htm
The docs claim that this Trigger.GetNextFireTimeUtc() method return a DateTime? but it actually returns a DateTimeOffset?. I don't really get what DateTimeOffset is for or why this function return one instead of a regular DateTime. All I want is the next time the trigger is going to run but in my timezone.
I did this trigger.GetNextFireTimeUtc().Value.DateTime but it gave me a time 2 hours early, i.e. the UTC time. How can I get the correct time according to my computer?
You can just use the DateTimeOffset.LocalDateTime property:
trigger.GetNextFireTimeUtc().Value.LocalDateTime
From the documentation:
If necessary, the LocalDateTime property converts the current DateTimeOffset object's date and time to the local system's date and time. The conversion is a two-step operation:
The property converts the current DateTimeOffset object's time to Coordinated Universal Time (UTC).
The property then converts UTC to local time.
You should really look into DateTimeOffset though - it's an important type to understand if you're using the BCL for date/time work.
I bumped to this problem and none of these was real answer (by this question title). Solution examples for question title:
var myDateTimeOffset = (DateTimeOffset)DateTime.UtcNow;
var ans1 = myDateTimeOffset.DateTime.ToLocalTime();
var ans2 = myDateTimeOffset.DateTime.ToLocalTime().ToLocalTime(); // ans1==ans2
.NET5 C# 9.0
This code is to convert utc to local
var local = utc.ToLocalTime();
I get date data from a user. That data is a date (e.g. 4/23/2011) and an hour (0 - 23), representing the time. This date/time that the user selects is a local time.
I need to convert this to a UTC DateTime. I have their GMTOffset for their location. How can I do this?
You should work with the DateTimeOffset structure, specifically, the constructor that takes the DateTime and the TimeSpan that represents the offset.
From there, conversions to/from UTC are a breeze, as the offset is embedded in the structure and not dependent on local system settings.
Note, even though not commonly adhered to, it is recommended to work with DateTimeOffset most of the time, as opposed to DateTime (see the note under the section titled "The DateTimeOffset Structure").
var utcDateTime =
new DateTimeOffset(userDateTime, TimeSpan.FromHours(userUtcOffset)).UtcDateTime;
Of course you can use TimeSpan differently if the GMT offset has minutes / fractions of an hour.
Just use the DateTime.ToUniversalTime in C#, will that do what you want?
UPDATE
I am dealing with a legacy database where the datetime values have been stored in a specific timezone (not UTC). Assume it is not possible to change how we are storing these values.
END UPDATE
Say I have a SQL Server 2005 database with a table as follows:
[id] (int) not null
[create_date] (datetime) not null
Suppose my [create_date] has been stored, by convention, as timezone TZ-A.
Suppose I want to retrieve this value (using SqlClient) from the database and display it in another timezone, TZ-B.
How do I do this?
DateTime from_db = // retrieve datetime from database, in timezone TZ-A
DateTime to_display = //convert from_db to another timezone, TZ-B
Use TimeZoneInfo
TimeZoneInfo timeZone1 = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");
TimeZoneInfo timeZone2 = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
DateTime to_display= TimeZoneInfo.ConvertTime(from_db, timeZone1, timeZone2);
I also agree that storing in UTC is the way to go. The only downside is trying to explain UTC to users who want to write their own reports.
Everyone has C# ways, I give you TSQL (sadly only 2008):
See below for doc, you probably want something like:
-- up here set the #time_zone variable.
SELECT
COl0, TODATETIMEOFFSET(COLDATE, #time_zone),.... ColN, from
Table_Original;
From MSDN
The SWITCHOFFSET function adjusts an
input DATETIMEOFFSET value to a
specified time zone, while preserving
the UTC value. The syntax is
SWITCHOFFSET(datetimeoffset_value,
time_zone). For example, the following
code adjusts the current system
datetimeoffset value to time zone GMT
+05:00:
SELECT
SWITCHOFFSET(SYSDATETIMEOFFSET(),
'-05:00');
So if the current system
datetimeoffset value is February 12,
2009 10:00:00.0000000 -08:00, this
code returns the value February 12,
2009 13:00:00.0000000 -05:00.
The TODATETIMEOFFSET function sets the
time zone offset of an input date and
time value. Its syntax is
TODATETIMEOFFSET(date_and_time_value,
time_zone).
This function is different from
SWITCHOFFSET in several ways. First,
it is not restricted to a
datetimeoffset value as input; rather
it accepts any date and time data
type. Second, it does not try to
adjust the time based on the time zone
difference between the source value
and the specified time zone but
instead simply returns the input date
and time value with the specified time
zone as a datetimeoffset value.
The main purpose of the
TODATETIMEOFFSET function is to
convert types that are not time zone
aware to DATETIMEOFFSET by the given
time zone offset. If the given date
and time value is a DATETIMEOFFSET,
the TODATETIMEOFFSET function changes
the DATETIMEOFFSET value based on the
same original local date and time
value plus the new given time zone
offset.
For example, the current system
datetimeoffset value is February 12,
2009 10:00:00.0000000 -08:00, and you
run the following code:
SELECT
TODATETIMEOFFSET(SYSDATETIMEOFFSET(),
'-05:00');
The value February 12, 2009
10:00:00.0000000 -05:00 is returned.
Remember that the SWITCHOFFSET
function returned February 12, 2009
13:00:00.0000000 -05:00 because it
adjusted the time based on the time
zone differences between the input
(-08:00) and the specified time zone
(-05:00).
As mentioned earlier, you can use the
TODATETIMEOFFSET function with any
date and time data type as input. For
example, the following code takes the
current system date and time value and
returns it as a datetimeoffset value
with a time zone -00:05:
SELECT TODATETIMEOFFSET(SYSDATETIME(),
'-05:00');
I'm not going to offer an answer, but rather a word of advice: Always store absolute dates in UTC, no matter what.
use the TimeZoneInfo class, it gives you built in time zone conversion functions using the Windows API.
http://msdn.microsoft.com/en-us/library/system.timezoneinfo.aspx
Always store the data in the database as UTC. Then convert it in the client for display purposes from UTC to the local time using DateTime.ToLocalTime();
Check the method TimeZoneInfo.ConvertTime.