sessions/main.py (45 lines of code) (raw):
# Copyright 2019 Google LLC 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.
# [START getting_started_sessions_all]
import random
from uuid import uuid4
from flask import Flask, make_response, request
from google.cloud import firestore
app = Flask(__name__)
db = firestore.Client()
sessions = db.collection('sessions')
greetings = [
'Hello World',
'Hallo Welt',
'Ciao Mondo',
'Salut le Monde',
'Hola Mundo',
]
@firestore.transactional
def get_session_data(transaction, session_id):
""" Looks up (or creates) the session with the given session_id.
Creates a random session_id if none is provided. Increments
the number of views in this session. Updates are done in a
transaction to make sure no saved increments are overwritten.
"""
if session_id is None:
session_id = str(uuid4()) # Random, unique identifier
doc_ref = sessions.document(document_id=session_id)
doc = doc_ref.get(transaction=transaction)
if doc.exists:
session = doc.to_dict()
else:
session = {
'greeting': random.choice(greetings),
'views': 0
}
session['views'] += 1 # This counts as a view
transaction.set(doc_ref, session)
session['session_id'] = session_id
return session
@app.route('/', methods=['GET'])
def home():
template = '<body>{} views for "{}"</body>'
transaction = db.transaction()
session = get_session_data(transaction, request.cookies.get('session_id'))
resp = make_response(template.format(
session['views'],
session['greeting']
)
)
resp.set_cookie('session_id', session['session_id'], httponly=True)
return resp
if __name__ == '__main__':
app.run(host='127.0.0.1', port=8080)
# [END getting_started_sessions_all]