README.md

datetoken

Featuring

• Token representation of relative dates. (dates whose value depends upon when they are evaluated)
• Time zone support. Time zones tend to be a major pending subject to many devs.
• Configure when week start. Cause not every country cries on Mondays.
• Business weeks. The previous point allows this.
• Quarters

Motivation

This package aims to solve a set of needs present in applications where dates need to be represented in a relative fashion, like background periodic tasks, datetime range pickers... in a compact and stringified format. This enables the programmer to persist these tokens during the lifetime of a process or even longer, since calculations are performed in the moment of evaluation. Theses tokens are also useful when caching URLs as replacement of timestamps, which would break caching given their mutability nature.

Some common examples of relative tokens:

	From	To
Today	now/d	now
Yesterday	now-d/d	now-d@d
Last 24 hours	now-24h	now
Last business week	now-w/bw	now-w@bw
This business week	now/bw	now@bw
Last month	now-1M/M	now-1M@M
Next week	now+w/w	now+w@w
Custom range	now+w-2d/h	now+2M-10h
Last month first business week	now-M/M+w/bw	now-M/+w@bw
This year	now/Y	now@Y
This quarter	now/Q	now@Q
This first quarter (Q1)	now/Q1	now@Q1
This second quarter (Q2)	now/Q2	now@Q2
This third quarter (Q3)	now/Q3	now@Q3
This fourth quarter (Q4)	now/Q4	now@Q4

As you may have noticed, token follow a pattern:

• The word now. It means the point in the future timeline when tokens are parsed to their datetime form.

• Optionally, modifiers to add and/or subtract the future value of now can be used. Unsurprisingly, additions are set via +, while - mean subtractions. These modifiers can be chained as many times as needed. E.g: now-1M+3d+2h. Along with the arithmetical sign and the amount, the unit of time the amount refers to must be specified. Currently, the supported units are:

  • s seconds
  • m minutes
  • h hours
  • d days
  • w weeks
  • M months
  • Y years
  • Q quarters

• Optionally, there exist two extra modifiers to snap dates to the start or the end of any given snapshot unit. Those are:

  • / Snap the date to the start of the snapshot unit.
  • @ Snap the date to the end of the snapshot unit.

  Snapshot units are the same as arithmetical modifiers, plus bw, meaning business week. With this, we achieve a simple way to define canonical relative date ranges, such as Today or Last month. As an example of the later:

  • String representation: now-1M/M, now-1M@M
  • Being today 15 Jan 2018, the result range should be: 2018-01-01 00:00:00 / 2018-01-31 23:59:59

Compatibility

This library has been developed under version 1.14 but you can expect the lib to work under lower versions too.

Installing

go get github.com/sonirico/datetoken.go

go mod install github.com/sonirico/datetoken.go

Examples

Most probably you will be dealing with simple presets such as yesterday or the last 24 hours.

package main

import (
    "fmt"
    "time"

    "github.com/sonirico/datetoken.go"
)

func main() {
    Madrid, _ := time.LoadLocation("Europe/Madrid")
    time, err := datetoken.Eval("now/d", Madrid, time.Monday)
    if err != nil {
        panic(err)
    }
    fmt.Println(time.String())
}

For more examples you can refer to https://github.com/sonirico/datetoken.go/tree/master/examples

Other versions

• python: https://github.com/sonirico/datetoken.py
• typescript: https://github.com/sonirico/datetoken.js