Can the property of an entity be another entity in Google Cloud Datastore?

Question

Here's what it says in the documentation:

Datastore mode supports a variety of data types for property values. These include, among others:

Integers

Floating-point

numbers

Strings

Dates

Binary data

Is it possible to assign an entity of a different type as a property of another entity in Google Cloud Datastore?

Answer 1

So you want to nest one entity inside of an another entity?

The python ORM ndb has something called the property type ndb.StructuredProperty()

https://cloud.google.com/appengine/docs/standard/python/ndb/entity-property-reference#structured

class Address(ndb.Model):
    type = ndb.StringProperty()  # E.g., 'home', 'work'
    street = ndb.StringProperty()
    city = ndb.StringProperty()

class Contact(ndb.Model):
    name = ndb.StringProperty()
    addresses = ndb.StructuredProperty(Address, repeated=True)

guido = Contact(
    name='Guido',
    addresses=[
        Address(
            type='home',
            city='Amsterdam'),
        Address(
            type='work',
            street='Spear St',
            city='SF')])

But this just trick that the ORM does. It actually gets stored as:

name = 'Guido'
addresses.type = ['home', 'work']
addresses.city = ['Amsterdam', 'SF']
addresses.street = [None, 'Spear St']

The arrays are how repeated entities are stored: https://cloud.google.com/appengine/docs/standard/python/ndb/entity-property-reference#repeated

EDIT:

So I just noticed from you other question that you are using Python3 which uses this library https://googleapis.github.io/google-cloud-python/latest/datastore/index.html

Unfortunately, that library is much less feature-ful than ndb. They are working on porting ndb over to python3, but it is still in alpha https://github.com/googleapis/python-ndb

However you could still try to save it the same way that ndb does

from google.cloud import datastore
client = datastore.Client()
key = client.key('Contact', 1234)
entity = datastore.Entity(key=key)
entity.update({
    'name': Guido',
    'addresses.type': ['home', 'work'],
    'addresses.city' = ['Amsterdam', 'SF']
    'addresses.street' = [None, 'Spear St']
})

The only part of this that I'm not sure with work is sending arrays for repeated properties