How to format current time into YYYY-MM-DDTHH:MM:SSZ - go

Never tried Go before and currently doing a small project. One of the task is to get current system time and represent it in YYYY-MM-DDT00:00:00Z format. I believe that Z means that time is represented in UTC format but when i looked into db, all timestamps are like this i.e., 2011-11-22T15:22:10Z.
So how can i format like this in Go?
Update
I was able to format it using following code
t := time.Now()
fmt.Println(t.Format("2006-01-02T15:04:05Z"))
Now the question remains, what Z signifies here. Should i get UTC Time?
Another question, it looks like that the value i am using to format impacts the output i.e., when i used 2019-01-02T15:04:05Z the output became 2029-02-02T20:45:11Z, why?


Go provides very flexible way to parse the time by example. For this, you have to write the "reference" time in the format of your choice. The reference time is Mon Jan 2 15:04:05 MST 2006. In my case, I used this reference time to parse the Now():
fmt.Println(time.Now().UTC().Format(time.RFC3339))
There are also other reference types if you want to see:
RFC822 = "02 Jan 06 15:04 MST"
RFC822Z = "02 Jan 06 15:04 -0700" // RFC822 with numeric zone
RFC850 = "Monday, 02-Jan-06 15:04:05 MST"
RFC1123 = "Mon, 02 Jan 2006 15:04:05 MST"
RFC1123Z = "Mon, 02 Jan 2006 15:04:05 -0700" // RFC1123 with numeric zone
RFC3339 = "2006-01-02T15:04:05Z07:00"
RFC3339Nano = "2006-01-02T15:04:05.999999999Z07:00"
Or you can use you desired reference.


"If a time is in Coordinated Universal Time (UTC), a "Z" is added directly after the time without a separating space. "Z" is the zone designator for the zero UTC offset. "09:30 UTC" is therefore represented as "09:30Z" or "0930Z". Likewise, "14:45:15 UTC" is written as "14:45:15Z" or "144515Z".[16]"
From https://en.wikipedia.org/wiki/Time_zone#UTC
// Some valid layouts are invalid time values for time.Parse, due to formats
// such as _ for space padding and Z for zone information.
and
// Replacing the sign in the format with a Z triggers
// the ISO 8601 behavior of printing Z instead of an
// offset for the UTC zone. Thus:
// Z0700 Z or ±hhmm
// Z07:00 Z or ±hh:mm
// Z07 Z or ±hh
From the source for package time/format.go

Related

Calculate the Closest Time Difference in HH:MM(am/pm) Format using Go

I got a bit problem when calculating the time difference from PM to AM or vice versa. For instance:
ref, _ := time.Parse("03:04pm", "11:59pm")
t, _ := time.Parse("03:04am", "12:00am")
fmt.Println(t.Sub(ref).Minutes()) // Got -719, my expectation is 1 (minutes)
Actually that's true, but I want to get the smallest difference.

The reason you got -719 is that you do not provide date information and in second time.Parse you have typo in template. Template has to contain pm
time.Parse("03:04pm", "11:59pm") // 0000-01-01 23:59:00 +0000 UTC
time.Parse("03:04am", "12:00am") // 0000-01-01 12:00:00 +0000 UTC
You need to provide day information and pm in template
time.Parse("02 03:04pm", "01 11:59pm") // 0000-01-01 23:59:00 +0000 UTC
time.Parse("02 03:04pm", "02 12:00am") // 0000-01-02 00:00:00 +0000 UTC
see https://stackoverflow.com/a/69338568/12301864

How to set the Zone of a Go time value when knowing the UTC time and time offset?

I have an UTC time and a time offset in seconds, and need to return the corresponding Go time value.
It is trivial to instantiate the UTC time value by using the time.Unix() function. But to set the Zone, I need to determine the time.Location.
How can I find the time.Location when knowing the UTC time and time offset ?

Without an actual entry to lookup in the time zone database, you can't know the true location for the time. If you want to work with just an offset, you can create a fixed location using time.FixedZone
edt := time.FixedZone("EDT", -60*60*4)
t, _ := time.ParseInLocation("02 Jan 06 15:04", "15 Sep 17 14:55", edt)
fmt.Println(t)
// 2017-09-15 14:55:00 -0400 EDT
You can opt to specify a non-existent zone name, or none at all, as long as the output format you use doesn't require one.
minus4 := time.FixedZone("", -60*60*4)
t, _ = time.ParseInLocation("02 Jan 06 15:04", "15 Sep 17 14:55", minus4)
fmt.Println(t.Format(time.RFC3339))
// 2017-09-15T14:55:00-04:00

convert string to time and parse in golang

I'm reading a timestamp from a file, and I assign the value to t:
t := "2016-11-02 19:23:05.503705739 +0000 UTC"
When I attempt to parse the string:
time, err := time.Parse("2016-11-02 19:18:57.149197306 +0000 UTC", t)
The result is:
0001-01-01 00:00:00 +0000 UTC
But I expected result to be:
"2016-11-02 19:18:57.149197306 +0000 UTC" ?
Please advise.

You're not correctly providing the layout argument to Parse. You're supposed to be using Mon Jan 2 15:04:05 MST 2006 (this is magic value, you put create a string in the format you want but with that date) in the given format so in your case, it would be 2006-01-02 15:04:05.000000000 +0000 UTC plus the offset which I don't know off the top of my head for MST.

Golang timestamp parsing

I'm trying to parse the timestamp Oct 12 2016 13:59:27 UTC using the following code.
eventDateLayout := "Jan _2 2006 15:04:00 UTC"
eventCheckDate, _ := time.Parse(eventDateLayout,"Oct 12 2016 13:59:27 UTC")
fmt.Println(eventCheckDate)
Result if 0001-01-01 00:00:00 +0000 UTC which is not the expected.
Can this timestamp parsed with golang time library?

In addition to the incorrect time layout, I'd recommend handling the error instead of throwing it away.
It gives you a helpful error message that you can use to efficiently debug:
cannot parse "27 UTC" as ":00 UTC"
Go playground (note the outputted time will be different)

How to format current time using a yyyyMMddHHmmss format?

I'm trying to format the current time using this format yyyyMMddHHmmss.
t := time.Now()
fmt.Println(t.Format("yyyyMMddHHmmss"))
That is outputting:
yyyyMMddHHmmss
Any suggestions?

Use
fmt.Println(t.Format("20060102150405"))
as Go uses following constants to format date,refer here
const (
stdLongMonth = "January"
stdMonth = "Jan"
stdNumMonth = "1"
stdZeroMonth = "01"
stdLongWeekDay = "Monday"
stdWeekDay = "Mon"
stdDay = "2"
stdUnderDay = "_2"
stdZeroDay = "02"
stdHour = "15"
stdHour12 = "3"
stdZeroHour12 = "03"
stdMinute = "4"
stdZeroMinute = "04"
stdSecond = "5"
stdZeroSecond = "05"
stdLongYear = "2006"
stdYear = "06"
stdPM = "PM"
stdpm = "pm"
stdTZ = "MST"
stdISO8601TZ = "Z0700" // prints Z for UTC
stdISO8601ColonTZ = "Z07:00" // prints Z for UTC
stdNumTZ = "-0700" // always numeric
stdNumShortTZ = "-07" // always numeric
stdNumColonTZ = "-07:00" // always numeric
stdFracSecond0 = ".0", ".00" // trailing zeros included
stdFracSecond9 = ".9", ".99" // trailing zeros omitted
)

This question comes in top of Google search when you find "golang current time format" so, for all the people that want to use another format, remember that you can always call to:
t := time.Now()
t.Year()
t.Month()
t.Day()
t.Hour()
t.Minute()
t.Second()
For example, to get current date time as "YYYY-MM-DDTHH:MM:SS" (for example 2019-01-22T12:40:55) you can use these methods with fmt.Sprintf:
t := time.Now()
formatted := fmt.Sprintf("%d-%02d-%02dT%02d:%02d:%02d",
t.Year(), t.Month(), t.Day(),
t.Hour(), t.Minute(), t.Second())
As always, remember that docs are the best source of learning: https://golang.org/pkg/time/

Option 1: Go standard library
t.Format("20060102150405")
Unit
Golang Layout
Examples
Note
Year
06
21, 81, 01
Year
2006
2021, 1981, 0001
Month
January
January, February, December
Month
Jan
Jan, Feb, Dec
Month
1
1, 2, 12
Month
01
01, 02, 12
Day
Monday
Monday, Wednesday, Sunday
Day
Mon
Mon, Wed, Sun
Day
2
1, 2, 11, 31
Day
02
01, 02, 11, 31
zero padded day of the month
Day
_2
⎵1, ⎵2, 11, 31
space padded day of the month
Day
002
001, 002, 011, 031, 145, 365, 366
zero padded day of the year
Day
__2
⎵⎵1, ⎵⎵2, ⎵11, ⎵31, 365, 366
space padded day of the year
Part of day
PM
AM, PM
Part of day
pm
am, pm
Hour 24h
15
00, 01, 12, 23
Hour 12h
3
1, 2, 12
Hour 12h
03
01, 02, 12
Minute
4
0, 4 ,10, 35
Minute
04
00, 04 ,10, 35
Second
5
0, 5, 25
Second
05
00, 05, 25
10-1 to 10-9 s
.0 .000000000
.1, .199000000
Trailing zeros included
10-1 to 10-9 s
.9 .999999999
.1, .199
Trailing zeros omitted
Time zone
MST
UTC, MST, CET
Time zone
Z07
Z, +08, -05
Z is for UTC
Time zone
Z0700
Z, +0800, -0500
Z is for UTC
Time zone
Z070000
Z, +080000, -050000
Z is for UTC
Time zone
Z07:00
Z, +08:00, -05:00
Z is for UTC
Time zone
Z07:00:00
Z, +08:00:00, -05:00:00
Z is for UTC
Time zone
-07
+00, +08, -05
Time zone
-0700
+0000, +0800, -0500
Time zone
-070000
+000000, +080000, -050000
Time zone
-07:00
+00:00, +08:00, -05:00
Time zone
-07:00:00
+00:00:00, +08:00:00, -05:00:00
In Golang 1.17+ for fraction of seconds (.999 or .000) you can use , instead of . (,999 or ,000) but output is always with .!!! See https://github.com/golang/go/issues/48037
Option 2: strftime Go implementation
import strftime "github.com/itchyny/timefmt-go"
strftime.Format(t, "%Y%m%d%H%M%S")
See for more info
https://github.com/itchyny/timefmt-go
https://linux.die.net/man/3/strftime

import("time")
layout := "2006-01-02T15:04:05.000Z"
str := "2014-11-12T11:45:26.371Z"
t, err := time.Parse(layout, str)
if err != nil {
fmt.Println(err)
}
fmt.Println(t)
gives:
>> 2014-11-12 11:45:26.371 +0000 UTC

Time package in Golang has some methods that might be worth looking.
func (Time) Format
func (t Time) Format(layout string) string
Format returns a textual representation of the time value formatted according to layout, which defines the format by showing how the reference time,
Mon Jan 2 15:04:05 -0700 MST 2006
would be displayed if it were the value; it serves as an example of the desired output. The same display rules will then be applied to the time value. Predefined layouts ANSIC, UnixDate, RFC3339 and others describe standard and convenient representations of the reference time. For more information about the formats and the definition of the reference time, see the documentation for ANSIC and the other constants defined by this package.
Source (http://golang.org/pkg/time/#Time.Format)
I also found an example of defining the layout (http://golang.org/src/pkg/time/example_test.go)
func ExampleTime_Format() {
// layout shows by example how the reference time should be represented.
const layout = "Jan 2, 2006 at 3:04pm (MST)"
t := time.Date(2009, time.November, 10, 15, 0, 0, 0, time.Local)
fmt.Println(t.Format(layout))
fmt.Println(t.UTC().Format(layout))
// Output:
// Nov 10, 2009 at 3:00pm (PST)
// Nov 10, 2009 at 11:00pm (UTC)
}

Go standard library: time
now := time.Now()
fmt.Println(now) // 2009-11-10 23:00:00 +0000 UTC m=+0.000000001
fmt.Println(now.Format("20060102150405"))
fmt.Println(now.Format("2006/01/02/15/04/05"))
fmt.Println(now.Format("2006-01-02 15:04:05"))
fmt.Println(now.Format("2006-01-02 15:04"))
fmt.Println(now.Format("2006/01/02 15:04:05"))
fmt.Println(now.Format("2006/01/02 15:04:05 (-0700)"))
fmt.Println(now.Format("2006年01月02日 15:04"))
fmt.Println(now.Format(time.Layout)) // 01/02 03:04:05PM '06 -0700
fmt.Println(now.Format(time.ANSIC)) // Mon Jan _2 15:04:05 2006
fmt.Println(now.Format(time.UnixDate)) // Mon Jan _2 15:04:05 MST 2006
fmt.Println(now.Format(time.RubyDate)) // Mon Jan 02 15:04:05 -0700 2006
fmt.Println(now.Format(time.RFC822)) // 02 Jan 06 15:04 MST
fmt.Println(now.Format(time.RFC850)) // Monday, 02-Jan-06 15:04:05 MST
fmt.Println(now.Format(time.Kitchen)) // 3:04PM
fmt.Println(now.Format(time.Stamp)) // Jan _2 15:04:05
Go playground

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