# 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 = '{} views for "{}"' 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]