Issues getting DateTimeProperty() auto_now_add and auto_now attributes to work

[JustasCe]

I am having problems getting auto_now_add and auto_now to work.
As I understand it should assign appropriate values on inserts and and updates of the entity, I don't have to pass any values to it manually.

However I cannot get it to work.

Example when trying to create an Entity, put it to datastore and retrieve the same Entity based on it's key that was returned during the put()

import logging

from google.cloud.ndb import (
    Client,
    DateTimeProperty,
    Model,
    StringProperty,
)

logging.basicConfig(level=logging.DEBUG)


class User(Model):
    first_name = StringProperty()
    created_at = DateTimeProperty(indexed=True, auto_now_add=True)
    updated_at = DateTimeProperty(indexed=True, auto_now=True)


ndb_client = Client(project="project-name", namespace="ndb_tests")

with ndb_client.context():
    logging.debug(f"Putting a new user to a database")
    user_key = User(
        first_name="MyName",
    ).put()
    logging.debug(f"Retrieving data based on the returned user key: {user_key}")
    user = user_key.get()
    logging.debug(f"Retrieved user data: {user}")

Debug output

DEBUG:root:Putting a new user to a database
DEBUG:google.cloud.ndb._datastore_api:Commit(mode: NON_TRANSACTIONAL
mutations {
  upsert {
    key {
      partition_id {
        project_id: "project-name"
        namespace_id: "ndb_tests"
      }
      path {
        kind: "User"
      }
    }
    properties {
      key: "created_at"
      value {
        null_value: NULL_VALUE
      }
    }
    properties {
      key: "first_name"
      value {
        string_value: "MyName"
      }
    }
    properties {
      key: "updated_at"
      value {
        null_value: NULL_VALUE
      }
    }
  }
}
project_id: "project-name"
)
DEBUG:google.cloud.ndb._datastore_api:timeout=None
DEBUG:google.auth.transport.requests:Making request: POST https://oauth2.googleapis.com/token
DEBUG:urllib3.connectionpool:Starting new HTTPS connection (1): oauth2.googleapis.com:443
DEBUG:urllib3.connectionpool:https://oauth2.googleapis.com:443 "POST /token HTTP/1.1" 200 None
DEBUG:google.cloud.ndb._datastore_api:mutation_results {
  key {
    partition_id {
      project_id: "project-name"
      namespace_id: "ndb_tests"
    }
    path {
      kind: "User"
      id: 5739956077068288
    }
  }
  version: 1562351307488774
}
index_updates: 7

DEBUG:root:Retrieving data based on the returned user key: Key('User', 5739956077068288, namespace='ndb_tests')
DEBUG:google.cloud.ndb._datastore_api:Lookup(read_options {
}
keys {
  partition_id {
    project_id: "project-name"
    namespace_id: "ndb_tests"
  }
  path {
    kind: "User"
    id: 5739956077068288
  }
}
project_id: "project-name"
)
DEBUG:google.cloud.ndb._datastore_api:timeout=None
DEBUG:root:Retrieved user data: User(key=Key('User', 5739956077068288, namespace='ndb_tests'), created_at=None, first_name='MyName', updated_at=None)

As you can see from the logs created_at and updated_at values are both None even though both of the fields had either auto_now_add or auto_now set to True.

[cguardia]

This is a bug. The _prepare_for_put method, which should set the dates, is never called. Will take a look.

[cguardia]

Fixed, via #138.

[cguardia]

Thanks a lot for the bug report!