Convert Unix epoch as a string to time.Time on Go

Question

I'm reading a JSON file that contains Unix Epoch dates, but they are strings in the JSON. In Go, can I convert a string in the form "1490846400" into a Go time.Time?

Answer 1

There is no such function in time package, but it's easy to write:

func stringToTime(s string) (time.Time, error) {
    sec, err := strconv.ParseInt(s, 10, 64)
    if err != nil {
        return time.Time{}, err
    }
    return time.Unix(sec, 0), nil
}

Playground: https://play.golang.org/p/2h0Vd7plgk.

Answer 2

There's nothing wrong, or incorrect about the answer provided by @Ainar-G, but likely a better way to do this is with a custom JSON unmarshaler:

type EpochTime time.Time

func (et *EpochTime) UnmarshalJSON(data []byte) error {
    t := strings.Trim(string(data), `"`) // Remove quote marks from around the JSON string
    sec, err := strconv.ParseInt(t, 10, 64)
    if err != nil {
        return err
    }
    epochTime := time.Unix(sec,0)
    *et = EpochTime(epochTime)
    return nil
}

Then in your struct, replace time.Time with EpochTime:

type SomeDocument struct {
    Timestamp EpochTime `json:"time"`
    // other fields
}