Parse Time in Golang

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4 years ago

Table of Contents

Overview

Parse function of time package in golang can be used to parse the string representation of time into time.Time object

Package link – https://golang.org/pkg/time/#Parse

If you have worked with time/date formatting/parsing in other languages you might have noticed that the other languages use special placeholders for time/date formatting. For eg ruby language uses

%d for day
%Y for year

etc. Golang, instead of using codes such as above, uses date and time format placeholders that look like date and time only. Go uses standard time, which is:

Mon Jan 2 15:04:05 MST 2006  (MST is GMT-0700)
or 
01/02 03:04:05PM '06 -0700

So if you notice Go uses

01 for the day of the month,
02 for the month
03 for hours,
04 for minutes
05 for second
and so on

Below placeholder table describes the exact mapping. Go takes a more pragmatic approach where you don’t need to remember or lookup for the traditional formatting codes as in other languages

Type	Placeholder
Day	2 or 02 or _2
Day of Week	Monday or Mon
Month	01 or 1 or Jan or January
Year	2006 or 06
Hour	03 or 3 or 15
Minutes	04 or 4
Seconds	05 or 5
Milli Seconds (ms)	.000 //Trailing zero will be includedor .999 //Trailing zero will be omitted
Micro Seconds (μs)	.000000 //Trailing zero will be includedor .999999 //Trailing zero will be omitted
Nano Seconds (ns)	.000000000 //Trailing zero will be includedor .999999999 //Trailing zero will be omitted
am/pm	PM or pm
Timezone	MST
Timezone offset	Z0700 or Z070000 or Z07 or Z07:00 or Z07:00:00 or -0700 or -070000 or -07 or -07:00 or -07:00:00

Now coming back to time.Parse

time.Parse function takes in two arguments

First argument is the layout consisting of time format placeholder
Second argument is the actual formatted string representing time.

The way you have to go about this is to make sure that the layout string (first argument ) matches the string representation (second argument) of the time you want to parse into time.Time.

For parsing 2020-01-29, layout string should be 06-01-02 or 2006-01-02 or something which maps correctly based on the above placeholder table.

Similarly for parsing “2020-Jan-29 Wednesday 12:19:25” the layout string can be “2006-Jan-02 Monday 03:04:05”

time.Parse will raise an error if it encounters an error while parsing time.

Code

Below are the working Code Examples of time.Parse().

package main

import (
    "fmt"
    "time"
)

func main() {
    //Parse YYYY-MM-DD
    timeT, _ := time.Parse("2006-01-02", "2020-01-29")
    fmt.Println(timeT)

    //Parse YY-MM-DD
    timeT, _ = time.Parse("06-01-02", "20-01-29")
    fmt.Println(timeT)

    //Parse YYYY-#{MonthName}-DD
    timeT, _ = time.Parse("2006-Jan-02", "2020-Jan-29")
    fmt.Println(timeT)

    //Parse YYYY-#{MonthName}-DD WeekDay HH:MM:SS
    timeT, _ = time.Parse("2006-Jan-02 Monday 03:04:05", "2020-Jan-29 Wednesday 12:19:25")
    fmt.Println(timeT)

    //Parse YYYY-#{MonthName}-DD WeekDay HH:MM:SS PM Timezone TimezoneOffset
    timeT, _ = time.Parse("2006-Jan-02 Monday 03:04:05 PM MST -07:00", "2020-Jan-29 Wednesday 12:19:25 AM IST +05:30")
    fmt.Println(timeT)
}

Output:

2020-01-29 00:00:00 +0000 UTC
2020-01-29 00:00:00 +0000 UTC
2020-01-29 00:00:00 +0000 UTC
2020-01-29 12:19:25 +0000 UTC
2020-01-29 00:19:25 +0530 IST