Make default property value functionality the same as in the original datastore NDB.

[rotemvil1]

The original NDB behavior when using default parameter is passing the default value inside datastore even when initiating a Model without the relevant. Currently, that doesn't happen. The entity is being saved without the default value which means that you can't query on it and worst than that, if you'll change the default value in the application level it'll affect on retro actively inserted queries.

Python 2.7 NDB example code:

from google.appengine.ext import ndb

class DefaultTest(ndb.Model):
    myCounter = ndb.IntegerProperty(required=False, default=20)

example = DefaultTest(id=123)
example.put()

In python 2.7 this entity will be saved with myCounter=20 in datastore while in python 3.7 this entity will be saved as an empty (containing only a key, missing myCounter aka missing all default properties that wasn't set explicitly in the Model init).

Python 37 NDB example code:

    class DefaultTest(ndb.Model):
        myCounter = ndb.IntegerProperty(required=False, default=20)

    example = DefaultTest(id=123)
    client.put(example)

Can be checked easily with this code:

client.get(client.key('DefaultTest', 123))['myCounter']

Which will get an exception in the Python 3.7 DS while in the 2.7 DS it'll get the correct value.

[berlincode]

Hello and thank you for your report.

I totally agree with you that the behavior between python2 and python3.7 should be as close as possible.

The line you are changing should imho work exactly the same on both python2 and python3.7.

I've tried to reproduce your problem without success. On python2, python3.6 and python3.7 a non-set property with a default value is NOT stored! If you load the entity from the datastore ndb-orm shows you the default value from your model. This only works (of course) if you load your model class before fetching the entity. Maybe this might be the problem?

[rotemvil1]

Hey and thanks for the reply.

No offense but did you actually check my Python 2.7 code?
I've retried it now and the default parameter was actually STORED.
If you still can't reproduce that, I'll share a GCP project with you that you can test on it and see it's source code (which will contain this code + Flask..)
In the meanwhile, I'm adding an image from my GCP datastore (not emulator or any third party web UI that can interfere the results, real GCP datastore UI) after running my API in python 2.7:

API code:

@app.route('/api/ds_default_test'`, methods=['GET'])
def ds_default_test():
    from google.appengine.ext import ndb

    class DefaultTest(ndb.Model):
        myCounter = ndb.IntegerProperty(required=False, default=20)

    example = DefaultTest(id=123)
    example.put()
    return '{}'