carbon.Date changed after marshal/unmarshal

[artemklevtsov]

Hello,

I encountered an issue with the following code:

package main

import (
	"encoding/json"
	"fmt"
	"strings"
	"time"

	"github.com/golang-module/carbon/v2"
)

const dateLayout = "2006-01-02"

type Date struct {
	Time time.Time
}

// UnmarshalJSON decodes JSON representation date
func (d *Date) UnmarshalJSON(b []byte) error {
	s := strings.Trim(string(b), `"`) // remove quotes
	if s == "null" {
		return nil
	}

	t, err := time.Parse(dateLayout, s)
	if err != nil {
		return err
	}

	*d = Date{t}

	return nil
}

// MarshalJSON encode to JSON.
func (d Date) MarshalJSON() ([]byte, error) {
	if d.Time.IsZero() {
		return nil, nil
	}

	return []byte(fmt.Sprintf(`"%s"`, d.Time.Format(dateLayout))), nil
}

type A struct {
	Date1 carbon.Date `json:"date1"`
	Date2 Date        `json:"date2"`
}

func main() {
	a := A{
		Date1: carbon.Date{Carbon: carbon.CreateFromDate(2000, 1, 1, carbon.UTC)},
		Date2: Date{Time: time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC)},
	}

	data, err := json.Marshal(a)
	if err != nil {
		panic(err)
	}

	var b A

	err = json.Unmarshal(data, &b)
	if err != nil {
		panic(err)
	}

	fmt.Println(a.Date1.Carbon2Time().Unix(), b.Date1.Carbon2Time().Unix())
	fmt.Println(a.Date2.Time.Unix(), b.Date2.Time.Unix())
}

golang version: 1.21.0

carbon version: v2.2.3

time zone: Asia/Novokuznetsk

I expected to get:

946684800 946684800
946684800 946684800

But I actually get:

946715384 946659600
946684800 946684800

Thanks!

[artemklevtsov]

More compact example:

package main

import (
	"fmt"

	"github.com/golang-module/carbon/v2"
)

func main() {
	d1 := carbon.Date{Carbon: carbon.CreateFromDateTime(2000, 1, 1, 0, 0, 0, carbon.UTC)}
	d2 := carbon.Date{Carbon: carbon.ParseByLayout(d1.ToDateString(), carbon.DateLayout, carbon.UTC)}
	fmt.Println(d1 == d2)
}

Output:

false

[gouguoyin]

Date1: carbon.Date{Carbon: carbon.CreateFromDate(2000, 1, 1, carbon.UTC)}

The hours, minutes, seconds and nanosecond of CreateFromDate come from now, you can view the source code

func (c Carbon) CreateFromDate(year, month, day int, timezone ...string) Carbon {
	now := c.Now(timezone...)
	hour, minute, second := now.Time()
	return c.create(year, month, day, hour, minute, second, now.Nanosecond(), timezone...)
}

[artemklevtsov]

Thank you. I understand why this is happening. But I think it should be equal:

fmt.Println(a.Date1.Carbon2Time().Unix(), b.Date1.Carbon2Time().Unix())
fmt.Println(a.Date2.Time.Unix(), b.Date2.Time.Unix())

[gouguoyin]

a := A{
    Date1: carbon.Date{Carbon: carbon.CreateFromDate(2000, 1, 1, carbon.UTC)},
    Date2: Date{Time: time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC)},
}

The timestamps of Date1 and Date2 are not equal，If you want equality, you can

Date1: carbon.Date{Carbon: carbon.CreateFromDate(2000, 1, 1, carbon.UTC).StartOfDay()},

or

Date1: carbon.Date{Carbon: carbon.CreateFromDateTimeNano(2000, 1, 1, 0, 0, 0, 0, carbon.UTC)},

[gouguoyin]

Fixed bugs in v2.2.6 where the time zone was lost after json.Unmarshal
v2.2.5

v2.2.6

[artemklevtsov]

But code from the first post returns:

❯ go run main.go 
946743050 946684800
946684800 946684800
❯ cat go.mod 
module demo

go 1.21.0

require github.com/golang-module/carbon/v2 v2.2.6

[artemklevtsov]

I think it should be fixed: https://github.com/golang-module/carbon/issues/178#issuecomment-1695140491
Why are minutes and seconds used for the dates? Or we can add the separate method for this.

[gouguoyin]

In order to be consistent with the CreateFromTime method，if the year, month and day in CreateFromTime method are given as a default of 0, it is an illegal time format, so the default is taken from the current time.