datastore doesn't put nested struct in Go

Question

The structs look like this:

type Account struct {
  Username         string    // NameKey
  Password         []byte    `datastore:",noindex"`
  RegistrationTime time.Time `datastore:",noindex"`
  AppUser
}

type AppUser struct {
  LoginEntries []LoginEntry `datastore:",noindex"`
}

type LoginEntry struct {
  Timestamp time.Time `datastore:",noindex"`
  UserAgent string    `datastore:",noindex"`
  IP        string    `datastore:",noindex"`
}

I'm also sure I put the data correctly, because other data has no problem being updated, and I tried to fmt.Println the content of account Account right before saving it in datastore (Put(ctx, key, &account) and when I print it then I can see all the AppUser information.. but when I later Get the user then the AppUser info doesn't exist (just shows up as {[]}).

I'm quite certain I have stored nested struct slices before in datastore without any problems, so I'm quite confused as to what might be causing it..

The Put func:

func PutAccount(ctx context.Context, acc Account) (*datastore.Key, error) {
  if isValidUsername(acc.Username) != true {
    return nil, errors.New("Invalid username.")
  }
  var hashedPassword []byte
  if acc.RegistrationTime.IsZero() {
    var err error
    hashedPassword, err = bcrypt.GenerateFromPassword(acc.Password, 12)
    if err != nil {
      return nil, err
    }
  } else {
    hashedPassword = acc.Password
  }
  account := Account{
    Username:         strings.ToLower(acc.Username),
    Password:         hashedPassword,
    RegistrationTime: time.Now(),
    AppUser:          acc.AppUser}
  fmt.Println("PutAccount, account:", account) // before saving it prints the AppUser without problems
  key := datastore.NameKey("Account", account.Username, nil)
  return database.DatastoreClient().Put(ctx, key, &account)
}

the Get func:

func GetAccount(ctx context.Context, key *datastore.Key) (Account, error) {
  var account Account
  err := database.DatastoreClient().Get(ctx, key, &account)
  if err != nil {
    return account, err
  }
  return account, nil
}

Please show the code used to get and put your data. You may also want to try a flat struct for your Get to see if that works. — Marc
– Marc, Commented Dec 12, 2017 at 14:34
You may also want to take a look at stackoverflow.com/questions/14308530/… — Marc
– Marc, Commented Dec 12, 2017 at 14:38
@Marc please see edit. I also noticed that answer but I found the documentation to be quite confusing and complex — fisker
– fisker, Commented Dec 12, 2017 at 14:44
My point was that you need to figure out where this is going wrong. Is it the put or the get? You can narrow down the problem by moving to a flat struct, one where LoginEntries is a field of Account. Using other tools to check that the data is actually there would help too. — Marc
– Marc, Commented Dec 12, 2017 at 15:09
Embedded structs are flattened out. For details see: Datastore: Structured Properties — icza
– icza, Commented Dec 12, 2017 at 17:16

Marc · Accepted Answer · 2017-12-12 15:39:57Z

1

Using named struct works. eg:

type Account struct {
  Username         string    // NameKey
  Password         []byte    `datastore:",noindex"`
  RegistrationTime time.Time `datastore:",noindex"`
  AppUser          AppUser
}

As to why anonymous embedded struct do not, this is probably worthy of an issue.

edited Dec 12, 2017 at 15:39

answered Dec 12, 2017 at 15:26

Marc

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2 Comments

fisker Over a year ago

Thanks a lot, really appreciate it <3

Mr_Pink Over a year ago

It's not really "embedded" if it's named, now is it? ;)

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