Using flask-login extension with Firestore in Datastore mode (GoogleC…

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Co-authored-by: Todd Kopriva <43478937+ToddKopriva@users.noreply.github.com>

tutorials/using-flask-login-with-cloud-datastore/index.md

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+---
+title: Using Flask-Login with Cloud Firestore in Datastore mode
+description: Represent your Cloud Datastore entity with a Python class and use this for Flask-Login user management.
+author: komlasapaty
+tags: Flask Framework, Python 3
+date_published: 2020-09-24
+---
+
+In this tutorial, you implement user authentication using the popular Flask extension [Flask-Login](https://flask-login.readthedocs.io) with
+[Firestore in Datastore mode](https://cloud.google.com/datastore/docs/datastore-api-tutorial) as the database backend. This tutorial demonstrates the use of 
+Firestore in Datastore mode (as opposed to any relational database) as the database backend for user authentication with Flask-Login.
+
+The use of Flask-Login should not force you to abandon the power of Firestore in Datastore mode in favor of a relational database.
+
+This tutorial doesn't teach the fundamentals of Flask-Login or Firestore in Datastore mode.
+
+Basic familiarity with the following is assumed:
+
+- Flask
+- Flask-Login
+- App Engine
+- Firestore in Datastore mode
+
+## Requirements
+
+-  [Python3.7](https://www.python.org/downloads/) 
+-  [Flask](https://github.com/pallets/flask) 
+-  [Flask-Login](https://flask-login.readthedocs.io) 
+-  [Datastore Entity](https://datastore-entity.readthedocs.io)  
+
+## Introduction
+
+Flask-Login requires the user (that is, the application user) to be represented using a Python class with specific properties and methods provided. This 
+requirement of Flask-Login is straightforward when using a relational database such as MySQL or Postgres. Using an ORM toolkit like SQL-Alchemy, you can easily 
+create a user model/class to represent a user in a relational database. Methods and properties required by Flask-Login can then be added to the user model.
+
+However, for a NoSQL database like Firestore in Datastore mode, this Flask-Login requirement poses a challenge, because the pattern of using a model/class to 
+represent a database record does not directly apply.  
+
+This tutorial demonstrates how to model your Firestore in Datastore mode entity as a Python class, which lets you use popular Python libraries like 
+Flask-Login and WTForms.  
+
+To model a Datastore entity as a Python class, this tutorial uses the [Datastore Entity library](https://datastore-entity.readthedocs.io). Think of Datastore 
+Entity as an ORM-like library for Firestore in Datastore mode. 
+
+The author of this tutorial is also the author of the Datastore Entity library.  
+
+## Set up your local environment
+
+Projects that use the Datastore mode API require an active App Engine application, so you should already have the App Engine and Datastore mode APIs enabled in
+your Google Cloud project.  
+
+### Create and download service account key
+
+To connect to your Google Cloud service from your local machine, you need the appropriate credentials (service account key).
+
+1.  In the Cloud Console, go to the [**Service accounts** page](https://console.cloud.google.com/iam-admin/serviceaccounts).
+1.  Click **Create service account**.
+1.  Give the service account an appropriate name, such as `datastore-service-account`, enter a description, and click **Create**.
+1.  Under **Select a role**, type `Cloud Datastore Owner` in the filter field, select **Cloud Datastore Owner**, click **Continue**, and click **Done**.
+1.  On the **Service accounts** page, look for the service account that you just created, click the button at the far right end of the row in the
+    **Actions** column, and select **Create key** in the dropdown menu. 
+1.  Make sure that **JSON** is selected as the **Key type**, and click **Create**.
+
+    This automatically downloads the service account JSON key to your local machine. Take note of the filename.
+
+### Configure your service account on your local machine
+
+Point the environment variable `GOOGLE_APPLICATION_CREDENTIALS` to the location of the service account key you downloaded:
+
+* Linux or macOS:
+
+      export GOOGLE_APPLICATION_CREDENTIALS="/path/to/your/service-acount-key.json"
+
+* Windows, with Powershell:
+
+      $env:GOOGLE_APPLICATION_CREDENTIALS="/path/to/your/service-acount-key.json"
+
+* Windows, with Command Prompt:
+
+      set GOOGLE_APPLICATION_CREDENTIALS="/path/to/your/service-acount-key.json"  
+
+You are now ready to connect to your Firestore in Datastore mode.
+
+### Install required libraries
+
+Run the following command to install the required libraries:
+
+    pip install flask flask-login datastore-entity
+
+Installing `datastore-entity` installs the required official client library for Firestore in Datastore mode.
+
+## Create your Flask user model
+
+Model your `user` entity.
+
+```python
+from flask_login import UserMixin
+from datastore_entity import DatastoreEntity, EntityValue
+import datetime
+
+
+class User(DatastoreEntity, UserMixin):
+    username = EntityValue(None)
+    password = EntityValue(None)
+    status = EntityValue(1)
+    date_created = EntityValue(datetime.datetime.utcnow())
+
+    # other fields or methods go here...
+    #def authenticated(self, password):
+    #    ...
+```
+
+## Implement the Flask login view
+
+After the entity is modeled, you can fetch your user entity using familiar ORM patterns.
+
+Use the methods provided on your model to fetch the user record.
+
+An example Flask-Login view:
+
+```python
+from flask_login import login_user
+from models import User
+
+@page.route("/login", methods=['GET','POST'])
+def login():
+    form = LoginForm(next=request.args.get('next'))
+
+    if form.validate_on_submit():
+        identity = request.form.get('username')
+        password = request.form.get('password')
+
+        # fetch user using the 'username' property
+        # refer to the datastore-entity documentation for more
+        user = User().get_object('username',identity)
+
+        if user and user.authenticated(password):
+
+            if login_user(user, remember=True):
+                user.update_activity()
+
+                #handle optionally redirecting to the next URL safely
+                next_url = form.next.data
+                if next_url:
+                    return redirect(safe_next_url(next_url))
+
+                return redirect(url_for('page/dashboard.html'))
+            else:
+                flash('This account is not active','error')
+
+        else: 
+            flash('Login or password is incorrect','error')
+
+    return render_template("page/login.html", form=form)
+```
+
+## Conclusion
+
+You can employ the same approach to model any other Firestore in Datastore mode entity to persist and update data.
+
+This technique can let Firestore in Datastore mode be a drop-in replacement for your relational database with little to no code change.
+
+
+## What's next
+
+-  [Firestore in Datastore mode documentation](https://cloud.google.com/datastore)
+-  [Flask documentation](https://flask.palletsprojects.com/en/1.1.x/)
+-  [Flask-Login documentation](https://flask-login.readthedocs.io) 
+-  [Datastore Entity documentation](https://datastore-entity.readthedocs.io)
+-  [Flask-Login tutorial using Postgres](https://hackersandslackers.com/flask-login-user-authentication)