Convenience method to save any object into the GAE datastore using Go. For a full walk-though of what and why, see the article at http://www.mrvdot.com/all/creating-a-universal-save-method-in-go-on-gae

save.go

func Save(c appengine.Context, obj interface{}) (key *datastore.Key, err error) {
    kind, val := reflect.TypeOf(obj), reflect.ValueOf(obj)
    str := val
    if val.Kind().String() == "ptr" {
        kind, str = kind.Elem(), val.Elem()
    }
    if str.Kind().String() != "struct" {
        return nil, errors.New("Must pass a valid object to struct")
    }
    dsKind := kind.String()
    if li := strings.LastIndex(dsKind, "."); li >= 0 {
        //Format kind to be in a standard format used for datastore
        dsKind = dsKind[li+1:]
    }
    idField := str.FieldByName("ID")
    if idField.IsValid() && idField.Int() != 0 {
        key = datastore.NewKey(c, dsKind, "", idField.Int(), nil)
    } else {
        key = datastore.NewIncompleteKey(c, dsKind, nil)
    }
    if bsMethod := val.MethodByName("BeforeSave"); bsMethod.IsValid() {
        bsMethod.Call([]reflect.Value{reflect.ValueOf(c)})
    }
    key, err = datastore.Put(c, key, obj)
    if err != nil {
        c.Errorf("[utils/Save]: %v", err.Error())
    } else {
        if idField.IsValid() {
            idField.SetInt(key.IntID())
        }
        if asMethod := val.MethodByName("AfterSave"); asMethod.IsValid() {
            asMethod.Call([]reflect.Value{reflect.ValueOf(c), reflect.ValueOf(key)})
        }
    }
    return
}