I'm using protobufs with boltsec and I'm wondering about the proper place to handle Marshal and Unmarshal... Ben Johnson (Bolt author) recommended Protobufs with bolt since it allows you to rename fields, further helping to sidestep many database migration reasons.

Right now, Save does assume that the incoming data should be marshalled as json, meanwhile GetOne will pass back the raw data, so the caller must call json.Unmarshal...

Inside of the example boltsec_test.go you have:

        dbm.Save(bucketName, data.ID, data)

and

	resNew := new(Article)
	json.Unmarshal(bytes, resNew) {

Yet json.Marshal is inside of dbm.Save, but no json.Marshal in GetOne.

Do you think it's better to also include json.Unmarshal in GetOne so that both are consistent? Or possibly to remove marshal/unmarshal so that both sides match?

Assuming you like to have marshal/unmarshal embeded inside boltsec (seems more convenient to me!), what do you think of extending it to cover marshal/unmarshal with protobuf in addition to json?

If you are good with extending it, my thinking is to set the serialization method in the boltsec constructor so that the Save and Get method implementation would be a bit easier. Maybe even have the caller pass a marshal and unmarshal callback so boltsec itself doesn't have any extra dependencies?

Please let me know what you think of this and if you might accept a PR for it.

func TestDBMCreate(t *testing.T) {
	var err error
	bucketName := "article"

	dbm, err := NewDBManager("test.dat", "example", "secret", false, []string{bucketName})

	data := Article{
		ID:    "ID-0001",
		Title: "input with more than 16 characters",
	}

	if err = dbm.Save(bucketName, data.ID, data); err != nil {
		t.Errorf("TestDBMCreate save data return err: %s", err)
	}

	var bytes []byte
	if bytes, err = dbm.GetOne(bucketName, data.ID); err != nil {
		t.Errorf("TestDBMCreate GetOne return err: %s", err)
	}

	resNew := new(Article)
	if err = json.Unmarshal(bytes, resNew); err != nil {
		t.Errorf("json.Unmarshal return err: %s", err)
	}

	if resNew.Title != data.Title {
		t.Errorf("returned Title is not equal: new:%s, org: %s", resNew.Title, data.Title)
	}

	if err = dbm.Delete(bucketName, data.ID); err != nil {
		t.Errorf("TestDBMCreate Delete return err: %s", err)
	}

	return
}