I am writing a module in my Google AppEngine project in Go for performance reasons but need to be able to read from some of the entities I have in datastore. I wrote out the Go code to be able to read the entities I built out in Python but I am getting the following error:
datastore: flattening nested structs leads to a slice of slices: field "Messages"
Model Definitions in Python:
class ModelB(ndb.Model):
msg_id = ndb.StringProperty(indexed=False)
cat_ids = ndb.StringProperty(repeated=True, indexed=False)
list_ids = ndb.StringProperty(repeated=True, indexed=False)
default_list_id_index = ndb.IntegerProperty(indexed=False)
class ModelA(ndb.Model):
date_join = ndb.DateTimeProperty(auto_now_add=True)
name = ndb.StringProperty()
owner_salutation = ndb.StringProperty(indexed=False)
owner_email_address = ndb.StringProperty()
logo_url = ndb.StringProperty(indexed=False)
...
messages = ndb.LocalStructuredProperty(ModelB, name='bm', repeated=True)
And in Go:
type ModelB struct {
MessageID string `datastore:"msg_id,noindex"`
CategoryIDs []string `datastore:"cat_ids,noindex"`
ListIDs []string `datastore:"list_ids,noindex"`
DefaultListIDIndex int `datastore:"default_list_id_index,noindex"`
}
type ModelA struct {
DateJoin time.Time `datastore:"date_join,"`
Name string `datastore:"name,"`
OwnerSalutation string `datastore:"owner_salutation,noindex"`
OwnerEmailAddress string `datastore:"owner_email_address,"`
LogoURL string `datastore:"logo_url,noindex"`
Messages []ModelB `datastore:"bm,"`
}
Is there something I'm doing wrong here? Is just a feature incompatibility between Go vs Python model definitions?
Attempt to Decode ModelB
Re-define ModelA
as follows:
import pb "appengine_internal/datastore"
import proto "code.google.com/p/goprotobuf/proto"
type ModelA struct {
DateJoin time.Time `datastore:"date_join,"`
Name string `datastore:"name,"`
OwnerSalutation string `datastore:"owner_salutation,noindex"`
OwnerEmailAddress string `datastore:"owner_email_address,"`
LogoURL string `datastore:"logo_url,noindex"`
Messages []ModelB `datastore:"-"`
}
// Load is implemented for the PropertyLoaderSaver interface.
func (seller *ModelA) Load(c <-chan datastore.Property) error {
f := make(chan datastore.Property, 100)
for p := range c {
if p.Name == "bm" {
var val pb.EntityProto
err := proto.Unmarshal([]byte(p.Value.(string)), &val)
if err != nil {
return err
}
//TODO: Store result as a new ModelB
} else {
f <- p
}
}
close(f)
return datastore.LoadStruct(seller, f)
}
But I receive the following error:
proto: required field "{Unknown}" not set