Here's what I'm trying to do: the user submits a time in pacific, once submitted I use .replace to set the timezone to Pacific.
Pacific = time.USTimeZone(-8, "Pacific", "PST", "PDT")
addEvent.date = addEvent.date.replace(tzinfo=Pacific)
Once i've set the tzinfo, I'm doing a put. According to the python documentation of google appengine it says:
"If the datetime value has a tzinfo attribute, it will be converted to the UTC time zone for storage. Values come back from the datastore as UTC, with a tzinfo of None. An application that needs date and time values to be in a particular time zone must set tzinfo correctly when updating the value, and convert values to the timezone when accessing the value."
However, when I do a put(), i get the following error:
WARNING 2012-10-06 21:10:14,579 tasklets.py:399] initial generator _put_tasklet(context.py:264) raised NotImplementedError(DatetimeProperty date can only support UTC. Please derive a new Property to support alternative timezones.)
WARNING 2012-10-06 21:10:14,579 tasklets.py:399] suspended generator put(context.py:703) raised NotImplementedError(DatetimeProperty date can only support UTC. Please derive a new Property to support alternative timezones.)
Please note I am using NDB
Ok, so after doing that I assumed that maybe NDB doesn't automatically convert it into UTC. So then I tried to convert it to UTC using the following code:
class UTC(tzinfo):
def utcoffset(self, dt):
return timedelta(0)
def tzname(self, dt):
return str("UTC")
def dst(self, dt):
return timedelta(0)
and now I still get the same error even after I convert the pacific time to UTC and set the tzinfo name as "UTC".
Could really use a ton of help here...
thanks!
The solution is to remove the tzinfo completely from the time after converting to UTC.
timestamp = timestamp.replace(tzinfo=None)
Here my working example:
if my_date.utcoffset():
my_date = (my_date - my_date.utcoffset()).replace(tzinfo=None)
I ran into this using http://hnrss.org/. This was my solution.
import datetime
from dateutil import parser
your_date_string = 'Mon, 24 Oct 2016 16:49:47 +0000'
your_date = parser.parse(your_date_string)
# your_date is now a datetime.datetime object
your_date_minus_tz = your_date.replace(tzinfo=None)
Now try your put() and you should see 2016-10-24 16:49:47 in the Cloud datastore.
Related
I’m trying to work with date-fns-tz in my react-based webpage and couldn’t make the following use-case to work.
I have a date input in a form that should be submitted to the backend that stores the data in local timezone.
A user in GMT+2 timezone selects 14:00 on 1/Feb/2021 in the UI, which correlates to 1612180800 timestamp (as the UI was opened in GMT+2), but it should eventually get sent to the backend as 14:00 in GMT-8, which is actually 1612216800 timestamp.
What’s the right way to get this conversion (from 1612180800 --> 1612216800 ) to work?
I tried to work with various date-fns functions, but hadn’t found the right one.
You'll need two things to make this work correctly:
An IANA time zone identifier for the intended target time zone, such as 'America/Los_Angeles', rather than just an offset from UTC.
See "Time Zone != Offset" in the timezone tag wiki.
A library that supports providing input in a specific time zone.
Since you asked about date-fns, you should consider using the date-fns-tz add-on library.
Alternatively you could use Luxon for this.
In the past I might have recommended Moment with Moment-TimeZone, but you should review Moment's project status page before choosing this option.
Sticking with date-fns and date-fns-tz, the use case you gave is the very one described in the docs for the zonedTimeToUtc function, which I'll copy here:
Say a user is asked to input the date/time and time zone of an event. A date/time picker will typically return a Date instance with the chosen date, in the user's local time zone, and a select input might provide the actual IANA time zone name.
In order to work with this info effectively it is necessary to find the equivalent UTC time:
import { zonedTimeToUtc } from 'date-fns-tz'
const date = getDatePickerValue() // e.g. 2014-06-25 10:00:00 (picked in any time zone)
const timeZone = getTimeZoneValue() // e.g. America/Los_Angeles
const utcDate = zonedTimeToUtc(date, timeZone) // In June 10am in Los Angeles is 5pm UTC
postToServer(utcDate.toISOString(), timeZone) // post 2014-06-25T17:00:00.000Z, America/Los_Angeles
In your case, the only change is that at the very end instead of calling utcDate.toISOString() you'll call utcDate.getTime().
Note that you'll still want to divide by 1000 if you intend to pass timestamps in seconds rather than the milliseconds precision offered by the Date object.
You can use 'moment' to convert timezone.
1.Create a moment with your date time, specifying that this is expressed as utc, with moment.utc()
2.convert it to your timezone with moment.tz()
For example
moment.utc(t, 'YYYY-MM-DD HH:mm:ss')
.tz("America/Chicago")
.format('l');
I can't find a way of getting a date from Azure Search using only the date.
The dates in the index are like: "2019-10-15T18:00:00Z","2019-10-22T18:00:00Z","2019-10-29T18:00:00Z"
If I try StartDate/any(s: s eq 2019-10-15T18:00:00Z) I get results
But with StartDate/any(s: s eq 2019-10-15) nothing comes up
I have tried usin the date OData function like so: StartDate/any(s: date(s) eq 2019-10-15) but I get an error 'Function 'date' is not supported'.
Is there any way to get dates without using the time part?
The use of date literals in filters in Azure Search will no longer be supported starting in api-version 2019-05-06-Preview. This was an "accidental feature" that we never intended to support. The reason you don't get any results is because the implicit conversion from Edm.Date to Edm.DateTimeOffset assumes a time of midnight UTC, whereas the dates in your index are 6 PM UTC.
We recommend explicitly providing the time and offset (or Z for UTC) in filters to avoid this problem.
If you want Azure Search to natively support fields and filters of type Edm.Date, please vote for this User Voice suggestion.
Date and time values represented in the OData V4 format: yyyy-MM-ddTHH:mm:ss.fffZ or yyyy-MM-ddTHH:mm:ss.fff[+|-]HH:mm. Precision of DateTimeOffset fields is limited to milliseconds. If you upload DateTimeOffset values with sub-millisecond precision, the value returned will be rounded up to milliseconds.
When you upload DateTimeOffset values with time zone information to your index, Azure Search normalizes these values to UTC.
Refer to supported data types in Azure search.
We are using JavaMail API to send calendar entries. But the recipients of Outlook have time zone issues, as meetings show wrong timings. In general our approach is as follows:
First of all we have,
SimpleDateFormat iCalendarDateFormat = new SimpleDateFormat("yyyyMMdd'T'HHmmss");
we then use iCalendarDateFormat.setTimeZone(TimeZone.getTimeZone(receiverTimeZone));
Finally, we use Calendar.getInstance() for start and end to manipulate Calendar fields,
and hence we have Date startDate = startTime.getTime();
Date endDate = endTime.getTime();
When we are about to send request as per icalendar specification we have ,
"DTSTAMP:" + iCalendarDateFormat.format(startDate) + "\n" +
"DTSTART:" + iCalendarDateFormat.format(startDate)+ "\n" "DTEND:" + iCalendarDateFormat.format(endDate)+ "\n"
Is this the correct approach?. Please comment.
Thanks
tl;dr
iCalendar format tracks the date-time separately from its intended time zone. You must juggle both parts appropriately.
Always use java.time classes. Never use legacy classes like Calendar & SimpleDateFormat.
Details
Caveat: I have not used iCalendar data before. So I may be incorrect in my understanding.
Looking at pages 31-33 of the RFC 5545 spec, it seems the authors of that spec assume you always want the date-time to be recorded separately from the time zone.
A moment, a point on the timeline, needs the context of a time zone or offset-from-UTC. For example, "noon on the 23rd of January next year, 2021" is not a moment. We do not know if you mean noon in Tokyo Japan, noon in Toulouse France, or noon in Toledo Ohio US — all very different moments, several hours apart.
To provide the context of an offset, a date and time must be accompanied by a number of hours-minutes-seconds such as 08:00. For an offset of zero hours-minutes-seconds, use +00:00.
2021-01-23T12:00:00+00:00
As an abbreviation of an offset of zero, +00:00, the letter Z can be used, pronounced “Zulu”. For example:
2021-01-23T12:00:00Z
But, strangely, the iCalendar spec wants to track the date and the time-of-day separate from the time zone. So this:
2021-01-23T12:00:00
…and a time zone field elsewhere:
America/New_York
And the iCalendar spec opts for the harder-to-read “basic” variation allowed by ISO 8601, which minimizes the use of delimiters. So this:
20210123T120000
For such a string, we must parse as a LocalDateTime. This class represents a date with a time-of-day but lacking any time zone or offset-from-UTC.
DateTimeFormatter f = dateTimeFormatter.ofPattern( "uuuuMMdd'T'HHmmss" ) ;
String input = "20210123T120000" ; // “Basic” variation of ISO 8601 format.
LocalDateTime ldt = LocalDateTime.parse( input , f ) ;
To determine a moment, we must apply a time zone. I assume iCalendar uses proper time zone names (Continent/Region format) and not the 2-4 letter pseudo-zones such as PST, CST, IST, and so on.
String zoneName = receiverTimeZone ; // Variable name taken from your code example, though you neglected to show its origins.
ZoneId z = ZoneId.of( zoneName ) ;
Apply the zone to get a ZonedDateTime, a moment, a point on the timeline.
ZonedDateTime zdt = ldt.atZone( z ) ;
Going the other direction, let's start with the current moment.
ZoneId z = ZoneId.of( "Africa/Tunis" ) ;
ZonedDateTime now = ZonedDateTime.now( z ) ;
And generate string values for iCalendar.
DateTimeFormatter f = dateTimeFormatter.ofPattern( "uuuuMMdd'T'HHmmss" ) ;
String iCal_DateTime = now.format( f ) ;
String iCal_ZoneName = now.getZone().toString() ;
Never use the terrible legacy date-time classes bundled with the earliest versions of Java: Calendar, GregorianCalendar, java.util.Date, SimpleDateFormat, and so on. These were supplanted years ago by the modern java.time classes defined in JSR 310.
Hard to tell without seeing the actual content of your iCalendar file, along with the expected start and end datetime with timezone information but you seem to be generating the DTSTART in floating time (datetime with local time). Although your code sample seems to imply that you have access to the recipient's timezone (receiverTimezone), this is a very fragile approach.
Instead, you should use either the datetime with UTC time or the datetime with local time and timezone (where the timezone does not have to be the receiver timezone).
If the event is not recurring, the most simple approach is to use datetime with UTC time.
See https://www.rfc-editor.org/rfc/rfc5545#section-3.3.5 for the definition of each format.
I had same problem, for which I struggle lot. So below are my findings:
Outlook works smoothly with UTC Timezone. If we set date & time with UTC Timezone then outlook automatically converts this UTC Time into user corresponding Timezone. We will have to use 'Instant' object for DTSTART:, DTEND: and for DTSTAMP(Optional but recommended) also.
Quick Test just use "DTSTART:"+Instant.now() in ical String.
And in Java 8 for getting UTC Time java time API provides Instant.now() through which you can get your system time in UTC format. Java 8 also provides method like
a. Instant.ofEpochMilli() - This returns Instant which can directly use in ical Sting.
b. new Date().toInstant() Which returns UTC Instant object.
There are few scenarios where input date and time sources are different:
If you are fetching Date and Time from database then in this case database is not storing Timezone its only saving Date & Time. So first convert the Date & Time in that Timezone in which it was saved in database, in my case I was storing Date & Time after converting in 'EST' Timezone and Date value was of EST but time zone was not there in DB. So while fetching Date & Time value from DB I have appended Timezone in the Date value and then further converted to EPOC time using below method
public static long getEpocTimeWithTimezone(Date date) {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
DateTimeFormatter dateTimePattern = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime dateTime = LocalDateTime.parse(simpleDateFormat.format(date), dateTimePattern);
long epochInMilliSeconds = dateTime.atZone(ZoneId.of("America/New_York")).toEpochSecond() * 1000;
return epochInMilliSeconds;
}
Then Just Use as below code for ical String:
Instant startDt = Instant.ofEpochMilli(getEpocTimeWithTimezone(//pass your date here
)).truncatedTo(ChronoUnit.MINUTES);
Now set this Instant object(startDt) directly to "DTSTART:":
"DTSTART:"+startDt+"....then in same fashion "DTEND:" also.
In second scenario you have Date with Timezone (make sure after conversion you did not loses your actual Timezone, Like in 1st scenario after saving Date in DB we actually lost Timezone but it was showing Timezone IST that was dummy so be careful about this)
So in this case just assume myDateObject is Date object. So just get the Instant (which
will be in UTC) object from myDateObject by using toInstant() of Date class.
Instant startDt = myDateObject.toInstant().truncatedTo(ChronoUnit.MINUTES);
I am using .truncatedTo(ChronoUnit.MINUTES); because if we will not use this then
we might get some extra min or second in Meeting invite Time section.
So the final String for outlook mail should be some like:
.
.
.
"BEGIN:VEVENT\n"+
"DTSTART:"+startDt+"\n"+
"DTEND:"+endDt+"\n"+
.
.
.
VVI Note: Since Z is representation of UTC time zone, So just adding Z in the last of Time will not be UTC zoned Time, You will have to convert the Date & Time then only accurate time will come on Outlook. For verifying your Time is in UTC format or not just save the .ics attached file (which you got in Email) in local and check Date & Time are coming as DTSTART:2020-05-15T13:57:00Z or not If not then you are not converting the Date correctly in UTC.
I'm working on a project that was used only in one country but now is in using in several countries.
So I'm working in some DateTime issues, as you can image.
I'm using angular js for my frontend, python for my backend and Postgres as my database in this project.
To avoid any problem with DateTime and try to make more easy to work with the timezones I'm saving the DateTime in the database as UTC.
from DateTime import DateTime
# inside a class of my entity
self.start_date = datetime.utcnow()
This is working fine, the problem is when I try to convert the date back.
For example.
If my application is running in a country with GMT -1, when the user
asks to save the entity and it's 2016-07-13 15:00:00, in the database
(using the UTC now()) the DateTime will become 2016-07-13 16:00:00.
But when I try to get back the value I have two scenarios:
If I don't do anything, I'll receive the DateTime like it's on the database, "2016-07-13 14:00:00"
If I try to convert to the local timezone, I'm getting like 2016-07-13 17:00:00. The time was increased by 1 and not decrease was I expected.
I'm trying to use the momentjs library to work with dates, but nothing seems to work.
I'm wondering if what I supposed to do is get the GMT, like (-01:00) then do some math with the DateTime that comes from the database, like sub or sum the GMT hours difference.
Solution:
My solution for this was, store everything as UTC in my database.
Retrieve the datetime as UTC and covert to browsers timezone using momentjs library.
Doing like this.
moment.tz(moment.utc(datetime), moment.tz.guess());
I am using the Go runtime to store entities in the Appengine Datastore sequenced by the time they were added; to store the timestamp in the key I am formatting the timestamp using the time.Time.String() method and storing the string version as the key.
To get the Time back again on retrieval I use time.Parse:
time.Parse("2006-01-02 15:04:05.000000000 +0000 UTC", the_timestamp)
In unit testing this functionality independent of an app (using cmdline - goapp test) my tests retrieve the timestamp in its entirety no problem.
But when I import the package doing this into an appengine app and test it (using cmdline - goapp serve) the timestamp is stored with its Year field set to "0000"
When you are converting your time to string before saving into datastore, the extra 0s at the end of time are removed.
So,
2009-11-10 23:00:00.12300000 +0000 UTC
is converted into
2009-11-10 23:00:00.123 +0000 UTC
Now when you retrieve it from datastore and use the Parse function, it tries to match upto 8 digits after decimal. Hence the error.
So, while converting the time into string, you need to Format the string so that 0s are not lost.
const layout = "2006-01-02 15:04:05.000000000 +0000 UTC"
t := time.Now()
tFormat := t.Format(layout)
http://play.golang.org/p/elr28mfMo8