TIL: Parsing dates and times in Go with time.Parse(...)

The Go module time provides standard library functions for manipulating time and date, including the Parse method with this signature:

func Parse(layout, value string) (Time, error)

layout is a string describing the format of the date or time value to be parsed. The time module provides several standard layouts as constant strings:

const (
    ...
    RFC822      = "02 Jan 06 15:04 MST"
    ...
    Stamp      = "Jan _2 15:04:05"
    ...
)

Many additional layouts are provided, as well as instructions for creating your own layout string, at the time module documentation.

This allows for straightforward parsing and manipulation of times and dates:

time, err := time.Parse(time.Stamp, timestampString)

if err != nil {
    panic(err)
}

fmt.Println(time.Format(time.RFC822))

value is just the string to be parsed. It should contain only the actual time/date string. If the string contains any text that does not match the specified format, you will receive an “extra text” error:

panic: parsing time "Sep  5 13:32:02 dnsmasq[8211]: query[AAAA] crawl.akrasiac.org from <INTERNAL IP>": extra text: " dnsmasq[8211]: query[AAAA] crawl.akrasiac.org from <INTERNAL IP>" 

The result of a properly formed call to time.Parse(...) with an appropriate layout and value is a Go time object. By default, unless your string includes time zone information, the time zone for the new time is UTC. time.ParseInLocation(...) provides the ability to define a time zone by providing a Location parameter, such as one returned by time.FixedZone(...) or time.LoadLocation(...).

Tags: til golang