runtime: python27

api_version: 1

threadsafe: true

builtins:

- deferred: on

handlers:

- url: /.*

script: main.app

libraries:

- name: webapp2

version: "2.5.2"

- name: jinja2

version: "2.6"

import logging

import os

from google.appengine.ext import deferred

from google.appengine.ext import ndb

import jinja2

import webapp2

import models_v1

import models_v2

JINJA_ENVIRONMENT = jinja2.Environment(

loader=jinja2.FileSystemLoader(

os.path.join(os.path.dirname(__file__), 'templates')),

extensions=['jinja2.ext.autoescape'],

autoescape=True)

class DisplayEntitiesHandler(webapp2.RequestHandler):

"""Displays the current set of entities and options to add entities

def get(self):

# Force ndb to use v2 of the model by re-loading it.

reload(models_v2)

entities = models_v2.Picture.query().fetch()

template_values = {

'entities': entities,

}

template = JINJA_ENVIRONMENT.get_template('index.html')

self.response.write(template.render(template_values))

class AddEntitiesHandler(webapp2.RequestHandler):

"""Adds new entities using the v1 schema."""

def post(self):

# Force ndb to use v1 of the model by re-loading it.

reload(models_v1)

# Save some example data.

ndb.put_multi([

models_v1.Picture(author='Alice', name='Sunset'),

models_v1.Picture(author='Bob', name='Sunrise')

])

self.response.write("""

""")

class UpdateSchemaHandler(webapp2.RequestHandler):

"""Queues a task to start updating the model schema."""

def post(self):

deferred.defer(update_schema_task)

self.response.write("""

""")

def update_schema_task(cursor=None, num_updated=0, batch_size=100):

"""Task that handles updating the models' schema.

# Force ndb to use v2 of the model by re-loading it.

reload(models_v2)

# Get all of the entities for this Model.

query = models_v2.Picture.query()

pictures, cursor, more = query.fetch_page(batch_size, start_cursor=cursor)

to_put = []

for picture in pictures:

# Give the new fields default values.

# If you added new fields and were okay with the default values, you

# would not need to do this.

picture.num_votes = 1

picture.avg_rating = 5

to_put.append(picture)

# Save the updated entities.

if to_put:

ndb.put_multi(to_put)

num_updated += len(to_put)

logging.info(

'Put {} entities to Datastore for a total of {}'.format(

len(to_put), num_updated))

# If there are more entities, re-queue this task for the next page.

if more:

deferred.defer(

update_schema_task, cursor=query.cursor(), num_updated=num_updated)

else:

logging.debug(

'update_schema_task complete with {0} updates!'.format(

num_updated))

app = webapp2.WSGIApplication([

('/', DisplayEntitiesHandler),

('/add_entities', AddEntitiesHandler),

('/update_schema', UpdateSchemaHandler)])

from google.appengine.ext import deferred

import pytest

import webtest

import main

import models_v1

import models_v2

def app(testbed):

yield webtest.TestApp(main.app)

def test_app(app):

response = app.get('/')

assert response.status_int == 200

def test_add_entities(app):

response = app.post('/add_entities')

assert response.status_int == 200

response = app.get('/')

assert response.status_int == 200

assert 'Author: Bob' in response.body

assert 'Name: Sunrise' in response.body

assert 'Author: Alice' in response.body

assert 'Name: Sunset' in response.body

def test_update_schema(app, testbed):

reload(models_v1)

test_model = models_v1.Picture(author='Test', name='Test')

test_model.put()

response = app.post('/update_schema')

assert response.status_int == 200

# Run the queued task.

tasks = testbed.taskqueue_stub.get_filtered_tasks()

assert len(tasks) == 1

deferred.run(tasks[0].payload)

# Check the updated items

reload(models_v2)

updated_model = test_model.key.get()

assert updated_model.num_votes == 1

assert updated_model.avg_rating == 5.0

from google.appengine.ext import ndb

class Picture(ndb.Model):

author = ndb.StringProperty()

name = ndb.StringProperty(default='')

from google.appengine.ext import ndb

class Picture(ndb.Model):

author = ndb.StringProperty()

name = ndb.StringProperty(default='')

# Two new fields

num_votes = ndb.IntegerProperty(default=0)

avg_rating = ndb.FloatProperty(default=0)

{#

# Copyright 2015 Google Inc. All Rights Reserved.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

#}

<head>

</head>

<body>

<p>If you've just added or updated entities, you may need to refresh

the page to see the changes due to

<a href="https://cloud.google.com/datastore/docs/articles/balancing-strong-and-eventual-consistency-with-google-cloud-datastore/">eventual consitency.</a></p>

{% for entity in entities %}

<p>

Author: {{entity.author}},

Name: {{entity.name}},

{% if 'num_votes' in entity._values %}

Votes: {{entity.num_votes}},

{% endif %}

{% if 'avg_rating' in entity._values %}

Average Rating: {{entity.avg_rating}}

{% endif %}

</p>

{% endfor %}

{% if entities|length == 0 %}

<form action="/add_entities" method="post" method="post">

<input type="submit" value="Add Entities">

</form>

{% endif %}

{% if entities|length > 0 %}

<form action="/update_schema" method="post" method="post">

<input type="submit" value="Update Schema">

</form>

{% endif %}

</body>