Go App Engine Datastore에서 동적 속성을 구현하는 방법은 무엇입니까?

package main

import (
    "context"
    "time"

    "google.golang.org/appengine/datastore"
)

func main() {
    ctx := context.Background()

    props := datastore.PropertyList{
        datastore.Property{Name: "time", Value: time.Now()},
        datastore.Property{Name: "email", Value: "example@example.com"},
    }

    k := datastore.NewIncompleteKey(ctx, "DynEntity", nil)
    key, err := datastore.Put(ctx, k, &props)
    if err != nil {
        // Handle error
    }

    // ...
}

package main

import (
    "context"

    "google.golang.org/appengine/datastore"
)

type DynEnt map[string]interface{}

func (d *DynEnt) Load(props []datastore.Property) error {
    for _, p := range props {
        (*d)[p.Name] = p.Value
    }
    return nil
}

func (d *DynEnt) Save() ([]datastore.Property, error) {
    var props []datastore.Property
    for k, v := range *d {
        props = append(props, datastore.Property{Name: k, Value: v})
    }
    return props, nil
}

func main() {
    ctx := context.Background()

    d := DynEnt{"email": "example@example.com", "time": time.Now()}

    k := datastore.NewIncompleteKey(ctx, "DynEntity", nil)
    key, err := datastore.Put(ctx, k, &d)
    if err != nil {
        // Handle error
    }

    // ...
}

d["active"] = true
datastore.Put(ctx, key, &d)