how to marshaller

mashaller-interface.go

package something

import (
	"encoding/json"
	"strconv"
)

type SomeData struct {
	SomeSlice []int `json:"some_slice"`
}

func (sd *SomeData) AsStrings() []string {
	strings := []string{}

	for _, id := range sd.SomeSlice {
		strings = append(strings, string(id))
	}

	return strings
}

func (sd *SomeData) MarshalJSON() ([]byte, error) {
	type Alias SomeData
	return json.Marshal(&struct {
		SomeSlice []string `json:"some_slice"`
		*Alias
	}{
		Alias:     (*Alias)(sd),
		SomeSlice: sd.AsStrings(),
	})
}

func (sd *SomeData) UnmarshalJSON(data []byte) error {
	type Alias SomeData
	aux := &struct {
		SomeSlice []string `json:"some_slice"`
		*Alias
	}{
		Alias: (*Alias)(sd),
	}
	if err := json.Unmarshal(data, &aux); err != nil {
		return err
	}

	sd.SomeSlice = []int{}
	for _, str := range aux.SomeSlice {
		i, _ := strconv.Atoi(str)
		sd.SomeSlice = append(sd.SomeSlice, i)
	}

	return nil
}