The result of dateparse.ParseFormat() function to infer timestamp is confusing

[xueyuncheng]

When I use the dateparse.ParseFormat() function to process the timestamp, I expect it to return error, but instead of returning an error, it returns the layout as the timestamp itself, which seems very confusing. Maybe returning an error would be more appropriate?

func main() {
	layout, err := dateparse.ParseFormat("1744709364")
	if err != nil {
		fmt.Println(err)
		return
	}

	// output: 1744709364
	fmt.Println(layout)
}

[klondikedragon]

@xueyuncheng thanks for the feedback! what are you trying to accomplish by using ParseFormat rather than ParseAny? "1744709364" is actually a valid timestamp as it is a Unix epoch time.

I've found that the dateparse.ParseFormat function doesn't produce accurate results for every single time format supported by this library. The intent of that function is to return the go date format string that could be used with time.Parse to parse other strings with a timestamp in the same exact format as the input string to dateparse.ParseFormat. But the go lib time.Parse doesn't support format strings that can parse all of the types of times that dateparse lib can parse properly.

Also, the intent of this library is to be "fast enough" to not have to know the date format in advance for a given string. So rather than using dateparse.ParseFormat to extract a fixed format string and use that to parse data, my recommendation would be to just pass every input string to dateparse.ParseAny or dateparse.ParseIn. Does that make sense, or for your use case is there a need explicitly for ParseFormat?

[xueyuncheng]

Thanks for your reply.

In my use case, I have a log file with a time field, all in the same format. I considered using datetime.ParseFormat() to infer the format once and then process all records with it, as this might be faster than using datetime.ParseIn() for each record. However, if datetime.ParseIn() performs adequately, the difference may not be significant. Therefore, I’ll opt for dateparse.ParseIn() to keep things simple.

Should we clarify the comment on datetime.ParseFormat() further, or is it already sufficient?