When I looked at #264, the reason I marked it "blocked" was because I couldn't find a way to get the prefix. I thought maybe you had found something I hadn't, but when I look at your solution, it's something I had already tried. I just don't get a prefix when I do this:

Python 3.7.5 (default, Nov 20 2019, 09:21:52) 
[GCC 9.2.1 20191008] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from google.cloud import ndb
>>> client = ndb.Client()
>>> client.project
'ndb-system-tests-chrisrossi'
>>> with client.context() as context:
...     print(context.client.project)
... 
ndb-system-tests-chrisrossi
>>> 

The problem I found is that the Datastore GUI was giving us ursafe keys with the prefix, but we had no way to get the prefix on the client side. I still don't see a way forward on that.

Am I missing something?

Thanks Chris,

We are actually trying to preserve original ndb functionality - so when we serialize a key to urlsafe we would like to have the location_prefix included. I've also seen this called region_code as seen on GAE documentation

I tried not to change the interfaces as much as possible. However, there are certainly other ways to do this. For example, add location_prefix as a KWARG to ndb.Client().

Commit 1 example:

from google.cloud import ndb
client = ndb.Client(project='s~project-id')
project = ndb_client.client.project

Commit 2 example:

from google.cloud import ndb
client = ndb.Client(project='project-id')
key = ndb.Key('SomeKind', 1234)
urlsafe_key = key.legacy_urlsafe(location_prefix='s~')

Ok, so you're just presuming that the programmer already knows the prefix. That can probably work as a compromise. Let's see if @andrewsg gets anything out of the Datastore team about this.

Integrated in #348