time: doesn't parse RFC3339 properly

[aniketawati]

Time can't parse the layout constant for RFC3339 in the code itself.

For eg. Go playground link - http://play.golang.org/p/EJH53M__AH

    // Time value taken from go source https://github.com/golang/go/blob/master/src/time/format.go#L51
    layout := "2006-01-02T15:04:05Z07:00" // RFC3339
    tm, err := time.Parse(layout, layout) 
    if err != nil {
        fmt.Println("error", err)
        return
    }
    fmt.Println("Parsed time", tm)

Currently if there is any offset in time (non UTC time), time formats it in RFC3339 as - +07:00 instead of Z07:00

If Z07:00 is given, it gives an error

error parsing time "2006-01-02T15:04:05Z07:00": extra text: 07:00

[nickcarenza]

@aniketawati How did you resolve this?

[benbariteau]

For posterity: the time package docs describe this layout conversion with the Z (near the bottom of the linked section), which is that it shows "Z" instead of a time offset if the timezone is UTC, and +hh:mm or -hh:mm otherwise. Since this is one of the few examples of the reference time format not being an actually valid time, I can see the confusion.

[mdwhatcott]

Maybe the docs should be updated to reflect the insight shared by @firba1 ??

[ianlancetaylor]

@mdwhatcott firba1 is citing the docs, so I'm not sure what to change. I would encourage you to send in a change if you see how to make the docs better (https://golang.org/doc/contribute.html).

[mdwhatcott]

Thanks for the encouragement @ianlancetaylor. I received a good answer on stackoverflow just today that was more helpful for me than the docs, probably because it used complete real examples and was specific to the particular layout string I was using:

The time.RFC3339 format is a case where the format string itself isn't a valid time. You can't have a Z and an offset in the time string, but the format string has both because the spec can contain either type of timezone specification.

Both of these are valid RFC3339 times:

"2015-09-15T14:00:12-00:00"
"2015-09-15T14:00:13Z"

And the time package needs to be able to parse them both using the same RFC3339 format string.