Golang : How to check if a date is within certain range?

Problem:

You are processing a large number of raw data files with dates as timestamps. However, you are only interested in processing the files within a certain range of a given date. For example, you want to process files that are two months before and after a given date. How to check if the dates on the files are within the 4 months range?

Solution:

This solution assumes that you've managed to extract(such as using awk) and isolate the dates from the filenames. It is a fairly simple process....get today's date, figure out the dates 2 months ago and 2 months later. (You can change the 2 months to any numbers you like)

The function below utilizes the time package Before() and After() function to check if the dates are within the 4 months range.

Here you go!

 package main

 import (
 "fmt"
 "time"
 )

 func DateWithinRange(dateString string, dateFormat string) (bool, error) {

 dateStamp, err := time.Parse(dateFormat, dateString)

 if err != nil {
 return false, err
 }

 today := time.Now()

 twoMonthsAgo := today.AddDate(0, -2, 0)  // minus 2 months
 twoMonthsLater := today.AddDate(0, 2, 0) // plus 2 months

 fmt.Println("Given : ", dateStamp.Format("02/01/2006"))
 fmt.Println("2 months ago : ", twoMonthsAgo.Format("02/01/2006"))
 fmt.Println("2 months later : ", twoMonthsLater.Format("02/01/2006"))

 if dateStamp.Before(twoMonthsLater) && dateStamp.After(twoMonthsAgo) {
 return true, nil
 } else {
 return false, nil
 }

 // default
 return false, nil
 }

 func main() {

 // dd/mm/yyyy
 result, err := DateWithinRange("27/04/2017", "02/01/2006")

 if err != nil {
 fmt.Println("Error :", err)
 }

 // %t to print boolean value in fmt.Printf
 fmt.Printf("Given date with range : [%t]\n", result)

 // yyyy-dd-mm
 result1, err := DateWithinRange("2017-27-04", "2006-02-01")

 if err != nil {
 fmt.Println("Error :", err)
 }

 fmt.Printf("Given date with range : [%t]\n", result1)

 // out of range example
 result2, err := DateWithinRange("2011-27-04", "2006-02-01")

 if err != nil {
 fmt.Println("Error :", err)
 }

 fmt.Printf("Given date with range : [%t]\n", result2)

 // out of range example
 result3, err := DateWithinRange("2018-17-09", "2006-02-01")

 if err != nil {
 fmt.Println("Error :", err)
 }

 fmt.Printf("Given date with range : [%t]\n", result3)
 }

Output:

Given : 27/04/2017

2 months ago : 27/02/2017

2 months later : 27/06/2017

Given date with range : [true]

Given : 27/04/2017

2 months ago : 27/02/2017

2 months later : 27/06/2017

Given date with range : [true]

Given : 27/04/2011

2 months ago : 27/02/2017

2 months later : 27/06/2017

Given date with range : [false]

Given : 17/09/2018

2 months ago : 27/02/2017

2 months later : 27/06/2017

Given date with range : [false]

References:

https://www.socketloop.com/tutorials/golang-change-date-format-to-yyyy-mm-dd

https://golang.org/pkg/time/#Time.Before

https://golang.org/pkg/time/#Time.After

https://www.socketloop.com/tutorials/golang-integer-is-between-a-range