I have a page that generates vCal and iCal files to import events into Outlook and iCal. These mail clients (Outlook & iCal) will take in the dates in UTC since they know the user's offset and will handle putting in the right times. Our client for which we're writing this code is based out of the USA Eastern time zone and so am I. Their host is in the Central time zone (1 hour behind Eastern). I'd like to make the code handle this without any hard-coded offsets. My code currently get's the DateTime from our CMS and converts to UTC for Outlook/iCal. That means the DateTime value from the CMS is relative to the hosting location:
// Start Date Time
sb.AppendFormat("DTSTART:{0}\n", thisEvent.StartDate.ToUniversalTime().ToString("yyyyMMddTHHmmssZ"));
When I run this on my local, it's all fine, because the DateTime in the CMS is based on our client's Eastern time zone and so am I, so the process is Eastern -> UTC -> into Outlook which then goes UTC -> Eastern, and everything is good. When I deploy to the server in Central, the DateTime from the CMS is an hour off from Eastern. How can I automatically get the offset from Eastern and add it in before I convert to UTC? I obviously need this to handle both standard time (EST) and daylight time (EDT). I'd like to do it programatically without hard-coded values so it always works correctly no matter what time zone you're in. I.e. if I deliver this code to someone for development in India, it should automatically handle their local server's offset and adjust accordingly.
I need to do something like this where I apply an offset to Eastern time before converting to UTC:
sb.AppendFormat("DTSTART:{0}\n", thisEvent.StartDate.ApplyEasternOffset().ToUniversalTime().ToString("yyyyMMddTHHmmssZ"));
Sorry if this is a topic that's been discussed before, I'm just not sure of the best terms to find a question like this. Thanks in advance.
Check out the TimeZoneInfo class. It has methods to get UTC offsets for any timezone.
http://msdn.microsoft.com/en-us/library/system.timezoneinfo.aspx
Also, check out this previous post: How to use TimeZoneInfo to get local time during Daylight Savings Time?
Here's an example showing a conversion from Pacfic to Eastern:
var eastern = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
var local = TimeZoneInfo.Local; // PDT for me
Console.WriteLine(DateTime.Now.Add(eastern.BaseUtcOffset - local.BaseUtcOffset));
Shows 4/4/2011 12:05:31 when my local clock shows 9:05:31.
You can use TimeZoneInfo Class.
Take a look at this sample:
TimeZoneInfo tzi = TimeZoneInfo.FindSystemTimeZoneById("US Eastern Standard Time");
TimeSpan offset = tzi.GetUtcOffset(DateTime.Now);
DateTime testDateTime = DateTime.Now.Add(offset);
Related
I am having a Issue with the C# function of TimeZoneInfo.ConvertTime().
What i need to get is the Standard Time not the DST but i'm only getting DST is there a way to Tell the Function to only get the Result in Standard Time.
My local Timezone is UTC -6:00 Central America Standard Time, so if my time is 12:00 PM the Conversion i'm getting is throwing it at 2 PM Eastern Time but i need it to tell me it's 1:00 PM.
public static DateTime TimetoEst( DateTime timenow)
{
var currentTimeZone = TimeZone.CurrentTimeZone.GetUtcOffset(timenow).ToString();
var estzone = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
var conver = TimeZoneInfo.ConvertTime(timenow, estzone);
return conver;
}
Thanks
A couple of things:
The ID "Eastern Standard Time" represents both EST and EDT, with the appropriate transitions in place. It would more appropriately be called "Eastern Time", but alas this is the identifier and the convention used by Windows time zones.
The Eastern Time zone really does transition in and out of daylight saving time. If you were to always adjust to just Eastern Standard Time (UTC-5), you would be ignoring the reality of timekeeping in that region - that it is in Eastern Daylight Time (UTC-4) for dates in the summer months.
Your code will indeed return EST, but only for date values that are outside of the DST period.
Now, if you still think this is what you want to do - then you can do it without the TimeZoneInfo object at all. Simply adjust the result from the offset that applies to your source value, to the UTC-5 offset that applies to EST.
public static DateTime TimetoEst(DateTime timenow)
{
var dto = new DateTimeOffset(timenow); // will use .Kind to decide the offset
var converted = dto.ToOffset(TimeSpan.FromHours(-5));
return converted.DateTime;
}
This is what you asked, but for the record - I don't think this is the best plan. Besides the issues above - assuming that the input value should be interpreted based on the local time zone is not necessarily a good idea - and unless the input time has a .Kind of DateTimeKind.Utc, it will indeed use the computer's local time zone.
You did label the variable as timenow. If you are just after a DateTime which represents the current time in a fixed offset, then it's much safer just to get it like so:
DateTime dt = DateTimeOffset.UtcNow.ToOffset(TimeSpan.FromHours(-5)).DateTime;
And if you really want the current time in the Eastern Time zone, taking DST into account when appropriate, then:
DateTime dt = TimeZoneInfo.ConvertTimeBySystemTimeZoneId(DateTime.UtcNow,
"Eastern Standard Time");
I know there are bunch of solutions on converting timezone to timezone, but what I'd like to know whether we can get eastern time without making conversion from our local time.
Well yes and no, if you represent using GMT always then you don't need to convert until you need to show locality.
Time is always in GMT and services should run under the GMT Timezone because of this reason among others.
Receiving and Storing a time in anything other than GMT / UTC requires conversions.
Please note the Timezone of the server should also be set to GMT for things to work as I indicated.
When you set things up like this it thus becomes much easier to reference and compare times and dates in different calendar date formats also.
This is the reason why DateTime offset made its way into the framework and sql server. if not careful when the Timezone on a server changes so does all stored and loaded dates in local format.
A date comparison is a date comparison. DateTime just wraps a memory structure which is defined in ticks and makes methods to access commonly used parts of the memory e.g. day or year or Time or TimeOfDay etc.
Furthermore conversion is only possible if you know both the source and destination offsets and then the calculation is always as given is given by -1 * (sourceOffset - destOffset)
Where the part in parenthesis represents the time zone difference.
Where the DateTime you want to convert is in UTC and called theDate
DateTime eastern = TimeZoneInfo
.ConvertTimeFromUtc(
theDate,
TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time"))
If theDate has a Kind of Local this will throw, only accepting Kind values of Utc or Unspecified. Of course, moving from local to UTC is easy and we could even check and do this conversion when required, but since you say you want this conversion "without making conversion from our local time" I'm assuming you have your times in UTC and hence having the exception would be better as it would warn you that times that should be UTC are being treat as local and a bug could pop up elsewhere.
This will use Eastern Daylight Time when theDate is a time when EDT is in effect, as that is the normal rule for EST. To use EST even when it is the summer you can create your own TimeZoneInfo:
TimeZoneInfo
.ConvertTimeFromUtc(
theDate,
TimeZoneInfo.CreateCustomTimeZone(
"Eastern Standard Time No Daylight Savings",
new TimeSpan(-5, 0, 0),
"Eastern Standard Time No Daylight Savings",
"Eastern Standard Time No Daylight Savings"))
I've read many SO articles, but I don't seem to be able to find a good answer to the problem. Posted suggestions include functions that convert dates to and from strings more then once, concatenating bits on the end and it all just seems... messy
So to the problem:
We have servers around the world. All servers run in their own local time and keep logs with time entries that are local to the server. Some servers are in DST observing areas, others arent
Suppose I have these strings from a log: 2013-01-01 12:34:56, 2013-07-01 12:34:56
And I know that this server is in New York so it's UTC-5 or UTC-4 when DST is in operation
And I have the same strings from a log on a server in Hong Kong, where DST does not apply and the time zone is +8
What I'm after is a block of code where I can tell it:
Here is a string representing a time
Here is the timezone the string is from
Daylight Savings should apply if relevant
And the code will parse the string into a DateTimeOffset, where the offset is adjusted according to DST if the time being parsed is DST relevant
For example:
NY server log says "2013-01-01 ..." DST does NOT apply to this date in JANUARY so the date parsed should be:
12:34:56 in new york time, a.k.a 17:34:56 in UTC (because it's -5, no DST)
NY server log says "2013-07-01 ..." DST DOES apply to this date in june so the date parsed should be:
12:34:56 in new york time, a.k.a 16:34:56 in UTC (because it's -4, with the DST)
HK server, both date times parse to 04:34:56 UTC
Thanks guys
Firstly, I'd strongly recommend that you change the system to log in UTC everywhere. It'll make your life much simpler.
If you're really stuck with what you've got, you should use DateTime.TryParseExact with a DateTimeStyles of just 0 (the default). That will give you a value with a DateTimeKind of Unspecified, which is what you want. (It's not UTC, and it's not local to the machine doing the parsing.)
You can then use TimeZoneInfo.GetUtcOffset (with the right time zone for that log) to work out the offset, and create a DateTimeOffset from the two together.
As a completely biased aside, you could also change to use the Noda Time project I maintain, which will allow your code to be much simpler to understand :)
To get the UTC-times of the time logged in the different log files you will need to know the names of the local time zones. Then you can use the DateTimeOffset-struct TimeZoneInfo-class to calculate the UTC-times:
public DateTime ParseAsUtc(string logDate, string timezoneName)
{
var timeZone = TimeZoneInfo.FindSystemTimeZoneById(timezoneName);
var localDate = DateTime.Parse(logDate);
var offset = new DateTimeOffset(localDate, timeZone.GetUtcOffset(localDate));
return offset.ToUniversalTime().DateTime;
}
ParseAsUtc("2013-01-01 12:34:56", "Eastern Standard Time"); //01.01.2013 17:34:56
ParseAsUtc("2013-07-01 12:34:56", "Eastern Standard Time"); //01.07.2013 16:34:56
ParseAsUtc("2013-01-01 12:34:56", "China Standard Time"); //01.01.2013 04:34:56
ParseAsUtc("2013-01-01 12:34:56", "China Standard Time"); //01.07.2013 04:34:56
All of our date/time data in our database is stored in UTC time. I'm trying to write a function to convert that UTC time into the user's preferred time zone (they can select their timezone in their profile so it has NOTHING to do with local settings on their computer and everything to do with which timezone they have selected from a dropdown of available choices.
This function is in the context of a DevExpress AspxGridView event (the third party control is not relevant to the question but I thought I'd mention it):
DateTimeOffset utcTime = (DateTimeOffset)e.Value;
TimeZoneInfo destTimeZone = Helper.GetTimeZoneInfo();
DateTime modifiedDate = TimeZoneInfo
.ConvertTimeFromUtc(utcTime.DateTime, destTimeZone);
e.DisplayText = String.Format("{0} {1}",
modifiedDate.ToString("g"),
destTimeZone.Abbreviation());
Helper.GetTimeZoneInfo() simply returns a TimeZoneInfo class that corresponds to the one the user selected, or defaults to "Pacific Standard Time" if they have not chosen one.
This generally works fine until I switch my system clock (which this server is running on) from today (which is Oct. 14, a DST date) to something like January 11, which is NOT DST.
The time seems to always be displayed in DST (i.e. always a 7 hour offset). No matter what I do with my system clock, I can't get the time to adjust for the extra hour.
For example, when I have my timezone set to Pacific Standard Time, for UTC time 10-10-2011 20:00:00, it is always displaying this time:
10-10-2011 13:00:00 (the DST time, offset of -7).
During non-Daylight Savings dates (standard), the time should be:
10-10-2011 12:00:00 (offset of -8).
What am I missing?
The converted local time of a UTC time is always based on the time zone info for that UTC time... not for whatever the current time happens to be.
That is, the PST offset on Oct 10, 2011 UTC is always -7. It doesn't matter what date you are doing the conversion on.
...Or am I misunderstanding what you are asking?
You might have a look at the e.Value.
Is the DateTimeKind for it set to DateTimeKind.Utc or is it DateTimeKind.Unspecified
If it is Unspecified, the conversion will not work correctly.
One cannot set the Kind directly. The best I have come up with is something along the lines of
// the value off the DB, but Kind is unspecified
var fromDb = new DateTime(1999,31,12)
// convert it to a Utc version of the same date
var fromDbInUtc = new DateTime(fromDb.Ticks, DateTimeKind.Utc)
var destTimeZone = Helper.GetTimeZoneInfo();
var local = TimeZoneInfo.ConvertFromUtc(fromDbInUtc, destTimeZone);
Hope this helps,
Alan.
I need to have a common function to convert UTC time to EDT. I have a server in India. An application in it needs to use EDT time for all time purposes.
I am using .NET 3.5.
I found this on some other forum.
DateTime eastern = TimeZoneInfo.ConvertTimeBySystemTimeZoneId(
DateTime.UtcNow, "Eastern Standard Time");
When i tried with "Easten Daylight Time" I got an error.
"The time zone ID 'Eastern Daylight Time' was not found on the local computer".
Please help with this or any other solution.
Eastern Daylight Time isn't the name of a "full" time zone - it's "half" a time zone, effectively, always 4 hours behind UTC. (There may be proper terminology for this, but I'm not aware of it.)
Why would you want to use EDT for times which don't have daylight savings applied? If you want a custom time zone that always has the same offset to UTC, use TimeZoneInfo.CreateCustomTimeZone.
Note that if you use get the Eastern Standard timezone (TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time")) then that will still have daylight saving time applied appropriately (i.e. during summer).
For example:
TimeZoneInfo tzi = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
// Prints True
Console.WriteLine(tzi.IsDaylightSavingTime(new DateTime(2009, 6, 1)));
// Prints False
Console.WriteLine(tzi.IsDaylightSavingTime(new DateTime(2009, 1, 1)));
I would have said that you should use UTC for calculations of time periods, so that you avoid issues of daylight saving time and then use LocalTime for display only.
DateTime.ToLocalTime for UTC to whatever the local time zone is and then DateTime.ToUniversalTime to convert from local time to UTC.
Edit after comment 1
Do I take it then that you're after displaying a different timezone to that of the server?
If you're using web pages to access your server then use
HttpRequest.UserLanguages to help create a CultureInfo object and use that to parse your DateTime object.
Look here for a full explanation:Microsoft link on displaying local user time for web pages.
If you're using client-server architecture then if the LocalTime call is on the client side it will display the LocalTime for the client. You then convert it to UTC to send back to your server.
Either way your server doesn't need to know where the client is so if you have multiple clients in multiple timezones then all calculations will match. It will also allow you to show the times in any timezone that you wish by use of different Culture objects.
Edit 2 copied my second comment
You can get time data in UTC format from the server. Then you can convert it using DateTime.ToLocalTime or DateTime.ToUniversalTime as requried. If you're including dates as well and need to cope with say US MM/dd/yyyy and european dd/MM/yyyy formats the you can use CultureInfo class to parse the DateTime value accordingly. It sounds like more work than what you have at the moment, but it would mean that if you move your server again then you don't need to recode the DateTime handling.
A new point
Another point to look at is clock synchronisation between the server and the clients using NTP (Network Time Protocol) or SNTP (Simple Network Time Protocol) if it is accurate enough. I don't know what OS you are using but this is used by Windows Server time services to synchronise networks.
The cowboy method is to take the UTC time, subtract four hours' worth of seconds from it (the timezone offset), format it using a UTC formatting function, and slap a "EDT" label on it.
If you need to use Daylight Time sometimes and Standard Time other times, either make a lookup table of switchover dates, or use some calendar function.
TimeZoneInfo.ConvertTimeFromUtc will have correct offset depending on the DateTime you give it. For example:
3AM UTC/11PM ET (4 hour offset):
DateTime timeSummerET = TimeZoneInfo.ConvertTimeFromUtc(Convert.ToDateTime("08/01/2019 03:00:00"), zoneET);
3AM UTC/10PM ET (5 hour offset):
DateTime timeWinterET = TimeZoneInfo.ConvertTimeFromUtc(Convert.ToDateTime("12/01/2019 03:00:00"), zoneET);