golang sql null to default value, and vice versa. json...

gosqlnull_test.go

package gosqlnull

import (
	"database/sql"
	"encoding/json"
	"testing"

	"github.com/stretchr/testify/assert"
)

type Int struct {
	sql.NullInt64
}

func NewInt(v int64) Int {
	return Int{sql.NullInt64{Int64: v, Valid: v != 0}}
}

func (v Int) MarshalJSON() ([]byte, error) {
	if v.Valid {
		return json.Marshal(v.Int64)
	}

	return json.Marshal(0)
}

func (v *Int) UnmarshalJSON(data []byte) error {
	var x *int64
	if err := json.Unmarshal(data, &x); err != nil {
		return err
	}

	if x != nil {
		v.Valid = true
		v.Int64 = *x
	} else {
		v.Valid = false
	}

	return nil
}

type String struct {
	sql.NullString
}

func NewString(v string) String {
	return String{sql.NullString{String: v, Valid: v != ""}}
}

func (v String) MarshalJSON() ([]byte, error) {
	if v.Valid {
		return json.Marshal(v.String)
	}

	return json.Marshal("")
}

func (v *String) UnmarshalJSON(data []byte) error {
	var x *string
	if err := json.Unmarshal(data, &x); err != nil {
		return err
	}

	if x != nil {
		v.Valid = true
		v.String = *x
	} else {
		v.Valid = false
	}

	return nil
}

type A struct {
	Value Int
}

type B struct {
	Value String
}

func TestMarshalInt(t *testing.T) {
	b, err := json.Marshal(A{Value: NewInt(0)})
	assert.NoError(nil, err)
	assert.NotEmpty(t, b)
	t.Log(string(b))
}

func TestMarshalString(t *testing.T) {
	b, err := json.Marshal(B{Value: NewString("")})
	assert.NoError(nil, err)
	assert.NotEmpty(t, b)
	t.Log(string(b))
}

func TestUnmarshalString(t *testing.T) {
	a := `
		{"Value": "bagus"}
	`
	var b B
	err := json.Unmarshal([]byte(a), &b)
	assert.NoError(t, err)
	assert.NotEmpty(t, b.Value.String)
	assert.True(t, b.Value.Valid)
	t.Log("hasil->" + b.Value.String)
}

func TestUnmarshalInt(t *testing.T) {
	a := `
		{"Value": 9}
	`
	var b A
	err := json.Unmarshal([]byte(a), &b)
	assert.NoError(t, err)
	assert.NotZero(t, b.Value.Int64)
	assert.True(t, b.Value.Valid)
	t.Log(b.Value.Int64)
}