app-engine-ndb

How do I get the equivalent result of the following query in NDB? Entity.all(keys_only=True).fetch(20) I know you can pass 'keys_only=True' to the iter() method. But what if I want to perform a keys only fetch, how do I do that in NDB? Found it in the GAE NDB Docs . The answer is Entity.query().fetch(20,keys_only=True) . 来源： https://stackoverflow.com/questions/10203874/whats-the-equivalent-of-entity-allkeys-only-true-fetch20-in-ndb

I have two models: Members and Events. A member can participe in many events and in an event, there are many participants. I think about like this: class Members(ndb.model): event = ndb.KeyProperty(repeated=True) class Events(ndb.model): member = ndb.KeyProperty(repeated=True) What's the best way to do many-to-many relationship? I think in this case you want to have an array/list of keys in one model pointing to the other model. Since there is a limit on the length of the array/list (the max is 5000 right now) you probably want to have the member model point to the events models (I am assuming

I'm trying to create an ndb model where each record has an unique field "name". I would like to define this field as the key_name field and use it to look up the records. Do I have to include a name field or can I somehow set the key_name field to an arbitrary string that the user can specify as long as it's unique? I'm thinking of using Model.get_or_insert to make sure that old records don't get overwritten, but is there a way to tell if the return value is newly created or pre-existing? I want to be able to display an error message if the user entered a duplicate name. Lastly, I tried to

I'm in the process of writing my first RESTful web service atop GAE and the Python 2.7 runtime; I've started out using Guido's shiny new ndb API. However, I'm unsure how to solve a particular case without the implicit back-reference feature of the original db API. If the user-agent requests a particular resource and those resources 1 degree removed: host/api/kind/id?depth=2 What's the best way to discover a related collection of entities from the "one" in a one-to-many relationship, given that the kind of the related entity is unknown at development time? I'm unable to use a replacement query

For the following (broken) function, I want to return True if the entity was created or updated, and False otherwise. The problem is that I do not know whether get_or_insert() got an existing entity, or inserted one. Is there an easy way to determine this? class MyModel(ndb.Model): def create_or_update(key, data): """Returns True if entity was created or updated, False otherwise.""" current = MyModel.get_or_insert(key, data=data) if(current.data != data) current.data = data return True return False get_or_insert() is a trivial function (although its implementation looks complex, because it