解组datastore.ByteString去

Question

Hi im trying to unmarshal datastore entity that contain ByteString field.

But i'm getting unmarshal error, i can't figure out a way to unmarshal it Should i create my own PropertyLoadSaver ??

json: cannot unmarshal string into Go value of type 



datastore.ByteString
package main

import (
    "encoding/json"
    "fmt"
    "google.golang.org/appengine/datastore"
)

type User struct {
    SubscriptionToken datastore.ByteString
}

func main() {
    u := new(User)
    str := "{\"SubscriptionToken\":\"YWR66969hjgkgkgo\"}"
    err := json.Unmarshal([]byte(str), &u)
    if err != nil {
        fmt.Println(err)

    }
    fmt.Println(u)
}

Answer 1

You need to use some intermediate type here. The json simply has a string, you can't directly unmarshal it into a ByteString without doing some custom unmarshaling implementation. Personally I would just use something like;

type jsonUser struct {
    SubscriptionToken string
}

type User struct {
    SubscriptionToken datastore.ByteString
}

Then provide a conversion method;

func NewUser(u jsonUser) *User {
     return &User{SubscriptionToken: StringToByteString(u.SubscriptionToken)}
}

So, unmarshal into the jsonUser type then convert it to a User