GCP Dev: 2. Storing Application Data in Cloud Datastore - Python

1_quiz_gcp_datastore.py

# Import the os module
import os

# Use the os module to get the GCLOUD_PROJECT environment variable
project_id = os.getenv('GCLOUD_PROJECT')

from flask import current_app

# Import the datastore module from the google.cloud package.
from google.cloud import datastore

# Declare a datastore.Client client object named datastore_client
datastore_client = datastore.Client(project_id)


"""
Create and persist and entity for each question
The Datastore key is the equivalent of a primary key in a relational database.
There are two main ways of writing a key:
1. Specify the kind, and let Datastore generate a unique numeric id
2. Specify the kind and a unique string id
"""
def save_question(question):
    # Create a key for a Datastore entity whose kind is Question
    key = datastore_client.key('Question')
    # Create a Datastore entity object using the key
    q_entity = datastore.Entity(key=key)
    # Iterate over the form values supplied to the function
    # & Assign each key and value to the Datastore entity
    for q_prop, q_val in question.iteritems():
        q_entity[q_prop] = q_val
    # Save the entity
    datastore_client.put(q_entity)
    
    
# Write code to retrieve Cloud Datastore entities
"""
Returns a list of question entities for a given quiz
- filter by quiz name, defaulting to gcp
- no paging
- add in the entity key as the id property 
- if redact is true, remove the correctAnswer property from each entity
"""
def list_entities(quiz='gcp', redact=True):
    query = datastore_client.query(kind='Question')
    query.add_filter('quiz', '=', quiz)
    results = list(query.fetch())
    for result in results:
        result['id'] = result.key.id
    if redact:
        for result in results:
            del result['correctAnswer']
    return results

2_GCP_Console.sh

cd ~/training-data-analyst/courses/developingapps/python/datastore/start
export GCLOUD_PROJECT=$DEVSHELL_PROJECT_ID
sudo pip install -r requirements.txt
python run_server.py
# Web preview > Preview on port 8080
# from GCP Console: Launch the code editor icon (looks like a pencil)

# Adding Entities to Cloud Datastore (form data of the quiz app)
# Create an App Engine application to provision Cloud Datastore
gcloud app create --region "us-central"
# (You aren't using App Engine for your web application yet. 
# but Cloud Datastore requires you to create an App Engine application in your project.)

# after updating quiz_gcp_datastore.py
python run_server.py
# Web preview > Preview on port 8080
# Navigation menu > Datastore > Entities