time.Since() with months and years

Question

I am trying to convert a timestamp like this:

2015-06-27T09:34:22+00:00

to a time since format so it would say like 9 months ago 1 day 2 ho

Answer 1

The solution proposed by izca is great, but it misses one thing. If you add the following example, you can see the effect:

a = time.Date(2015, 1, 11, 0, 0, 0, 0, time.UTC)
b = time.Date(2015, 3, 10, 0, 0, 0, 0, time.UTC)
fmt.Println(diff(a, b))
// Expected: 0 1 27 0 0 0
// Actual output: 0 1 30 0 0 0

playground

The code is calculating the remaining days of the next incomplete month based on the total days of the first month (y1,M1), but it needs to be computed from the previous month of the later date month (y2,M2-1).

The final code is as follows:

package main

import (
    "fmt"
    "time"
)


func DaysIn(year int, month time.Month) int {
    return time.Date(year, month+1, 0, 0, 0, 0, 0, time.UTC).Day()
}

func Elapsed(from, to time.Time) (inverted bool, years, months, days, hours, minutes, seconds, nanoseconds int) {
    if from.Location() != to.Location() {
        to = to.In(to.Location())
    }

    inverted = false
    if from.After(to) {
        inverted = true
        from, to = to, from
    }

    y1, M1, d1 := from.Date()
    y2, M2, d2 := to.Date()

    h1, m1, s1 := from.Clock()
    h2, m2, s2 := to.Clock()

    ns1, ns2 := from.Nanosecond(), to.Nanosecond()

    years = y2 - y1
    months = int(M2 - M1)
    days = d2 - d1

    hours = h2 - h1
    minutes = m2 - m1
    seconds = s2 - s1
    nanoseconds = ns2 - ns1

    if nanoseconds < 0 {
        nanoseconds += 1e9
        seconds--
    }
    if seconds < 0 {
        seconds += 60
        minutes--
    }
    if minutes < 0 {
        minutes += 60
        hours--
    }
    if hours < 0 {
        hours += 24
        days--
    }
    if days < 0 {
        days += DaysIn(y2, M2-1)
        months--
    }
    if months < 0 {
        months += 12
        years--
    }
    return
}

func main() {
    var a, b time.Time
    a = time.Date(2015, 5, 1, 0, 0, 0, 0, time.UTC)
    b = time.Date(2016, 6, 2, 1, 1, 1, 1, time.UTC)
    fmt.Println(Elapsed(a, b)) // Expected: false 1 1 1 1 1 1

    a = time.Date(2016, 1, 2, 0, 0, 0, 0, time.UTC)
    b = time.Date(2016, 2, 1, 0, 0, 0, 0, time.UTC)
    fmt.Println(Elapsed(a, b)) // Expected: false 0 0 30 0 0 0

    a = time.Date(2016, 2, 2, 0, 0, 0, 0, time.UTC)
    b = time.Date(2016, 3, 1, 0, 0, 0, 0, time.UTC)
    fmt.Println(Elapsed(a, b)) // Expected: false 0 0 28 0 0 0

    a = time.Date(2015, 2, 11, 0, 0, 0, 0, time.UTC)
    b = time.Date(2016, 1, 12, 0, 0, 0, 0, time.UTC)
    fmt.Println(Elapsed(a, b)) // Expected: false 0 11 1 0 0 0

    a = time.Date(2015, 1, 11, 0, 0, 0, 0, time.UTC)
    b = time.Date(2015, 3, 10, 0, 0, 0, 0, time.UTC)
    fmt.Println(Elapsed(a, b)) // Expected: false 0 1 27 0 0 0
}

playground