在NDB中查询PickleProperty

Question

I am trying to code a Twitter-like microblogging application. In order to do that I'm using Google App Engine and the Datatstore.

I have two classes. The Tweet class which is the parent :

class Tweet(EndpointsModel):

  _message_fields_schema = ('sender','body', 'name')

  sender = ndb.StringProperty()
  body = ndb.TextProperty()
  created = ndb.DateTimeProperty(auto_now=True)
  ...

And the TweetIndex class, which is the child that contains all the receivers for a tweet.

class TweetIndex(EndpointsModel):
  ...
  receivers = ndb.PickleProperty(indexed=True,repeated=True)
  created = ndb.DateTimeProperty(auto_now=True)
  ...

@TweetIndex.method(request_fields=('receivers',),
                    path='mymodels', name='mymodel.list')
def MyModelList(self, query):
if not query.from_datastore:
    raise endpoints.NotFoundException('MyModel not found.')
return query

I'm trying to query the TweetIndex entities with the API method MyModelList which purpose is to return the TweetIndex entity if a given id is included in the receivers array.

Example of a receivers array :

 ["13911772075915175317","1855429131779793831", ... ]

Which looks something like this in the datastore (stored as a blob):

["gAJYEwAAADY1NjU2NDM3MzA1NDI2NDU5ODlxAS4=","gAJYEwAAADU4MDM3MjE4OTEyNDgzNzgyNjNxAS4=",...]

However, when executing the following API request:

POST https://myapi/.../v1/mymodels

{
 "receivers": [
  "13911772075915175317"
 ]
}

The following is returned:

404

- Show headers -

{
 "error": {
  "errors": [
   {
    "domain": "global",
    "reason": "notFound",
    "message": "MyModel not found."
   }
  ],
  "code": 404,
  "message": "MyModel not found."
 }
}

"13911772075915175317" does exist at least once in a receivers array. I also tried to input the blobs in the request (but with no surprise) did not work either.

How am I supposed to query this array correctly?

Answer 1

You'll need to query your receivers array with the pickled version. Given that a PickledProperty is binary data, it won't be easy to query. You are probably better off changing from PickledProperty to whatever type you actually want, in this case IntegerProperty.