I have a DateTime in my .NET program that I need to print with particular value of time zone offset (for instance, +01:00 always). Output should contain full date time with timezone. It has to be unrelated to system timezone setting. How I could achieve this?
Example: I have a timestamp such as 12-03-2016T12:30:34+03:00 and I need to output it calculated for predefined TZ +1: 12-03-2016T10:30:34+01:00
Found some approach to it.
First of all, DateTime does not have time zone stored in it. Instead it has flag whether it is UTC or Local (without the idea what Local TZ shift is). So: first thing is to get your initial parsing of time from any string time stamp in UTC.
Once it is stored in DateTime object (with Kind=UTC), you have to convert it to the timezone you desire output for. I find examples here useful: datetime to string with time zone.
Note: if you need to convert London daylight-saving time, you have to know right names of timezones in NET so you get it right. See Difference between UTC and GMT Standard Time in .NET
Related
So I need to check whether the current time is after a EndDate, which is a date stored as 19:00 UTC. I only need to know if it's the next day.
This is what I'm currently doing
const now = moment();
const tooLate = now.isAfter(moment(EndDate), 'day');
I worry about timezones. I supposedly need this for central time. Is this sufficient? Or do I need to worry about the timezone? As I understand it, moment runs in UTC to start with.
Depends on the format of EndDate. By default moment() will parse in local time, so unless EndDate is a JS Date object, a unix timestamp (e.g. 1318781876406), or in string form with UTC offset (e.g. 2013-02-08 09:30:26.123+07:00) then you will have a problem if it is not in the same timezone as the client.
You can use moment.UTC() to parse in UTC time instead of local time. This should be enough to solve the any formatting problems you might have with EndDate
An API returns a timestamp as UNIX timestamp at UTC and I would like to know if this timestamp was more than x seconds ago. As expected, this works fine with os.time() - x > timestamp in UTC, but blows up in other timezones.
Unfortunately I can't find a good way solve this in lua.
os.date helpfully has the ! prefix (e.g. os.date("!%H:%M:%S")) to return time at UTC, but it seems that despite the documentation stating it supports all strftime options, this does not support the %s option. I have heard people mention that this is caused by Lua compile time options for a similar issue, but changing these is not possible as the interpreter is provided by the user.
You can use
os.time(os.date("!*t"))
to get the current UNIX epoch.
Ok, so you want the UTC time. Keep in mind that os.time actually knows nothing about timezones, so for example:
os.time(os.date("!*t"))
Will get UTC time and populate table struct.
Will convert table struct according to current timezone to unix timestamp.
So you actually would get your UNIX_TIME - TIMEZONE_OFFSET. If you are in GMT+5 you will get timestamp at UTC-5.
The correct way to do time conversion in lua is:
os.time() -- get current epoch value
os.time{ ... } -- get epoch value for local date/time values
os.date("*t"),os.date("%format") -- get your local date/time
os.date("!*t") or os.date("!%format") -- get UTC date/time
os.date("*t", timestamp),os.date("%format", timestamp) -- get your local date/time for given timestamp
os.date("!*t", timestamp) or os.date("!%format", timestamp) -- get UTC date/time for given timestamp
Kudos to Mons at https://gist.github.com/ichramm/5674287.
If you really need to convert any UTC date to timestamp, there's a good description on how to do this in this question: Convert a string date to a timestamp
os.time() gives you the unix timestamp. The timestamp is seconds since 00:00:00 UTC on 1 January 1970, so it's the same across timezones.
For example, run this code:
print('timestamp', os.time())
print('local hour', os.date("*t").hour)
print('utc hour', os.date("!*t").hour)
Presumably, your local and utc hour are different. Also run it in an online repl. The server's local and utc hour are the same, but both your and the server's timestamp are about the same.
I know this question has been hashed over multiple times and I read lots of posts on that hashing but still am confused.
Using MVC4/WebAPI, I have a datetime that is simply created as new DateTime.Now.
My WebAPI is return data like this:
HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.OK, new
{
data = sessionRecordSmalls,
count = sessionRecordSmalls.Count,
success = true
});
where sessionRecordsSmall has a public property of DateTime in it.
When I look at the date in the VS debugger, it shows it as now with no timezone of course because DateTime does not include a timezone.
{10/6/2012 9:45:00 AM}
When I look at what gets downloaded from the server, I see in the JSON
2012-10-06T09:45:00
I think the T0 means Timezone 0, not 100% sure of that. My JavaScript library interprets it as timezone 0, then shows the actual date downloaded as GMT (-9 hours ago for me).
My question is, what is the JSON downloaded? Is that include a timezone? Am I missing some important step here?
if serializing with json.net keep in mind that you can specify DateTimeZoneHandling.
Example in WebApiConf.cs
var json = config.Formatters.JsonFormatter;
json.SerializerSettings.DateTimeZoneHandling =Newtonsoft.Json.DateTimeZoneHandling.Local;
The date time 2012-10-06T09:45:00, which we recive in JSON with Web API and default serializer is the ISO 8601 format.
In fact this is so called Combined date and time representations. Extract:
..A single point in time can be represented by concatenating a
complete date expression, the letter T as a delimiter, and a valid
time expression. For example "2007-04-05T14:30"...
There is no time zone information in this format. As mentioned in the Time zone designators Extract:
Time zones in ISO 8601 are represented as local time (with the
location unspecified), as UTC, or as an offset from UTC. If no UTC
relation information is given with a time representation, the time is
assumed to be in local time.
In other words, if there is no offset from UTC specified, it is treated as a local time.
The UTC format would be extended with Z at the end
If the time is in UTC, add a Z directly after the time without a
space. Z is the zone designator for the zero UTC offset. "09:30 UTC"
is therefore represented as "09:30Z" or "0930Z". "14:45:15 UTC" would
be "14:45:15Z" or "144515Z".
UTC time is also known as 'Zulu' time, since 'Zulu' is the NATO phonetic alphabet word for 'Z'.
So, the date-time we recieve is the ISO 8601 format, treated as local time zone (no Z at the end like this 2012-10-06T09:45:00Z)
I have a field timestamp = models.DateTimeField(auto_now_add=True) in the db. I want to find the difference between that timestamp and datetime.now().
When I tried datetime.now() - timestamp, I get the error:
can't subtract offset-naive and offset-aware datetimes
How do I fix this?
This error refers to how times are stored by python. According to the python documentation:
There are two kinds of date and time objects: “naive” and “aware”. This distinction refers to whether the object has any notion of time zone, daylight saving time, or other kind of algorithmic or political time adjustment.
The django documentation also states that:
When time zone support is disabled, Django uses naive datetime objects
in local time. This is simple and sufficient for many use cases. In
this mode, to obtain the current time, you would write:
import datetime
now = datetime.datetime.now()
When time zone support is enabled,
Django uses time-zone-aware datetime objects. If your code creates
datetime objects, they should be aware too. In this mode, the example
above becomes:
import datetime
from django.utils.timezone import utc
now = datetime.datetime.utcnow().replace(tzinfo=utc)
You should determine whether or not you want timezone awareness in your site and then adjust your stored times accordingly. To convert an aware dt to naive you can use the pytz module and do this:
naive_dt = aware_dt.replace(tzinfo=None)
This works because all python datetimes have an optional timezone attribute, tzinfo, which can be used to store information on the dt's offset from UTC time.
Holá
The short answer is:
tz_info = your_timezone_aware_variable.tzinfo
diff = datetime.datetime.now(tz_info) - your_timezone_aware_variable:
You must add the timezone info to your now() time.
But you must add the same timezone of the variable, thats why I first read the tzinfo attribute.
My Application hosted at server in time zone which differs from mine. All date in database is not correct for my time zone.
How can I set my time zone for Application or how I can convert date to my time zone on output
Don't set the time zone for the process - use TimeZoneInfo from .NET 3.5 and higher to perform the relevant conversions.
Of course, that assumes you know the time zone that the data will come back in from the database... usually database records are kept in UTC, but not always...
There's very easy way to do it. Simply get the current UTC time and your timezone. Convert UTC to your timezone. Here's how you do it.
DateTime date1 = DateTime.UtcNow;
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("YOUR TIME ZONE (e.g. Pakistan Standard Time)");
DateTime date2 = TimeZoneInfo.ConvertTime(date1, tz);
Set your Time Zone in tz and then use "date2" anywhere.