CODEWITHSUNDEEP
pythongoogle-app-enginegoogle-cloud-datastoreapp-engine-ndb
PyGAE
PyGAE

Reputation: 51

Python, gae, ndb - get all keys in a kind

I know how to get all entities by a key using Book.get_by_id(key) where Book is an ndb.Model.

How do I get all the keys within my Kind? Is it using fetch()(https://cloud.google.com/appengine/docs/python/ndb/queryclass#Query_fetch) ?

Upvotes: 3

Views: 3975

Answers (3)

Y2H
Y2H

Reputation: 2537

If you only wish to get all keys just use

entity.query().fetch(key_only=True)

which will return a list of all keys in that entity group. If you wanna get the IDs and not keys you can also use:

map(lambda key: key.id(), entity.query().fetch(key_only=True))

Upvotes: 1

Brent Washburne
Brent Washburne

Reputation: 13138

If you only want the keys, use the keys_only keyword in the fetch() method:

Book.query().fetch(keys_only=True)

Then you can fetch all the entities using ndb.get_multi(keys). According to Guido, this may be more efficient than returning the entities in the query (if the entities are already in the cache).

Upvotes: 6

Mihail Russu
Mihail Russu

Reputation: 2536

With all_books = Book.query().fetch() the all_books variable will now have every entity of your Book model.

Note though that when you have lots of entities in the Book model - it won't be a good idea to load&show them all at once. You will need some kind of pagination implementation (depending on what exactly you're doing) - otherwise your pages will load forever which will create a bad experience for your users.

Read more at https://cloud.google.com/appengine/docs/python/ndb/queries

Upvotes: 5

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