Advanced Scalable Python Web Development Using Flask

Learn to create scalable web applications that can serve millions of users using Flask, MongoDB and Amazon AWS
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  • Lectures 71
  • Length 14 hours
  • Skill Level Intermediate Level
  • Languages English, captions
  • Includes Lifetime access
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    Available on iOS and Android
    Certificate of Completion
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About This Course

Published 8/2016 English Closed captions available

Course Description

This course will teach you some of the advanced development concepts used in the top tech companies today. How do I know this? Because I’ve been leading tech teams in both large enterprise as well as startup companies in New York City for the past 15 years.

Thousands of students have completed my "Professional Python Web Development Using Flask" Udemy Course, which introduced them to the basic concepts of Python and Flask and this course builds on top of that knowledge and takes you to the next step in web application architecture design.

The course goes through the process of building a social web application using Python Flask and the most popular document store database in the market: MongoDB. We will go over modeling best practices, how to build efficient indexes and how to interact with it using the popular MongoEngine ORM.

Step-by-step we will go over the user registration, login and management, the relationship model for users to become friends, and a scalable news feed system using the same architectural design that Twitter and other popular social applications have been using to handle massive amounts of user data.

Additionally we will setup and use Amazon’s AWS cloud infrastructure for this social application, and you will learn how to manage thousands of images using Amazon S3 and best-of-class email distribution using Amazon SES.

At the end of the course students will be challenged with a final project where all the course material will need to be used to complete it. Students that finish the final project will be eligible for special future promotions.

If you already know the basics of Python and Flask and you are interested in advancing your knowledge, this course will go over some of the advanced concepts of web application development, architecture design, database modeling and leveraging cloud infrastructure services.

The course is divided in 7 sections:

  • Introduction
  • Fundamental Concepts
  • MongoDB and Flask Blueprints
  • The User Module and an Introduction to AWS
  • The Relationship Module
  • The Feed Module
  • Final Project

The course has more than 13 hours of video tutorials as well as the source code at the end of each lesson, so that you can see exactly what the whole project looks like in each stage.

The course can take anywhere from 10 days to a month to complete based on how much material the student completes daily.

Additionally we’re constantly updating the course, adding contents thanks to the feedback of our students.

Join this course and continue your path to becoming a professional Python backend web developer!

What are the requirements?

  • A computer with internet access and administrative access to install packages
  • Good understanding of how to use the command line interface, internet and code editors
  • A credit card is required to open an account on the cloud infrastructure provider
  • Good knowledge of the Python programming language
  • Good knowledge of the Flask web framework
  • Basic knowledge of HTML, CSS and jQuery

What am I going to get from this course?

  • You will learn advanced concepts for Flask web development including Blueprints
  • You will be introduced to MongoDB and the concepts of NoSQL databases
  • You will learn strategies for scaling applications to millions of reads and writes per second
  • You will learn to use Amazon Web Services like S3 and SES through the Boto library

Who is the target audience?

  • Programmers and developers with basic Python knowledge who want to expand their skills
  • Application architects who want to understand better how to scale their applications
  • Software developers who want to understand how to build API applications
  • Startup CTOs who want to understand better best practices for application development
  • Computer Science Students who want to get exposed to real life concepts

What you get with this course?

Not for you? No problem.
30 day money back guarantee.

Forever yours.
Lifetime access.

Learn on the go.
Desktop, iOS and Android.

Get rewarded.
Certificate of completion.


Section 1: Introduction
  • This course is intended for people that have done some sort of initial Python Flask course and wants to learn advanced techniques for high traffic applications
  • We will cover topics like modular Flask application design, NoSQL databases, and scaling approaches
  • It is required that students have basic knowledge of Python, Flask and database concepts
Section 2: MongoDB and Flask Blueprints

Introduction to MongoDB

  • Databases and Collections
  • Indexes
  • Documents
  • ObjectId

  • To set it up you need to create a data directory: mkdir ~/data
  • You also need a log directory: mkdir ~/log
  • Create the mongodb config
  • Install mongodb by doing  sudo apt-get install -y mongodb-org
  • Start the client with mongod -f mongod.conf
  • Note: sometimes when your cloud9 instance goes to sleep without properly closing mongodb, you can get an errorexited with error number 100. Just delete the mongod.lock by doing rm -fr ~/data/mongod.lock.
  • Login to mongo mongo
  • Create a database by inserting a record: db.test.insert({name: "Jorge", last_name: "Escobar"})
  • Show the record by doing a find: db.test.find()
  • Insert another record and do another find
  • Do a find for a specific record: db.test.find({last_name:"Escobar"})
  • Create an index: db.records.createIndex( { last_name: 1 } )
  • Insert another document, completely different schema: db.test.insert({name: "Juan", last_name: "Escobar", age: 47})
  • Find that the record is still found: db.test.find({last_name:"Escobar"})
  • You can also do documents inside of documents: db.test.insert({name: {first_name: "Ricardo", last_name: "Escobar"}, age: 23})
  • That third record is not found: db.test.find({last_name:"Escobar"})
  • You can do conditional searches: db.test.find( { age: { $lt: 40 } } )
  • You can do AND searches: db.test.find( { name: "Jorge", last_name: "Escobar" } )

The factory pattern for Flask applications

  • Create
  • Create application
  • Create
  • Create a runner using:
    • Command: /home/ubuntu/workspace/flaskbook/venv/bin/python3 /home/ubuntu/workspace/flaskbook/ runserver
  • Run the app using RUN
  • Create the user folder and
  • Add user_app and user_app route with a simple return string
  • Register the user_app on
  • Run the app and check it works
Section 2 Quiz
3 questions
Section 3: The User Module and an Introduction to AWS
  • pip install flask-mongoengine
  • add mongoengine on
  • add user
  • Go to terminal and do: >>> from user.models import User >>> user = User(username='jorge', password='test', email='', first_name='Jorge', last_name='Escobar')
  • check on mongo the record exists
  • Do db.user.find({'u': 'jorge'}).explain() and explain how indexes are used ("cursor" : "BasicCursor", "nscannedObjects" : 3,)
  • Set username and email as unique, explain unique
  • Add indexes (explain why indexes)
  • Do python shell and update the user and then check db.user.getIndexes()
  • Do db.user.find({'u': 'jorge'}).explain() and explain how indexes are used ("cursor" : "BtreeCursor u_1", "nscannedObjects" : 1,)

Register User

  • Create templates folder
  • Create base, flashmessages, formhelpers (copy and paste from github, not important to explain this)
  • Add requirement.txt > flask-wtf and pip install -r
  • Create user and add registration form
  • Create templates > user > register.html (note the url_for ".register", for blueprints)
  • Add user > views register

- Implement the form error
- Install py-bcrypt
- Do the user registration with the salted password
- Try regitering with user "jorge" -- you will get a duplicate key error


Unit testing is a piece of code that tests a unit of work, logical unit in the tested system. Your unit tests should be:

- automated
- independent
- consistent and repeatable
- maintainable
- Start a user test file
- Make sure to override with `**config_overrides` and add the config_overrides
- Build the main file

- Login function


- Here we use context (the with function), because without the with block, 
    the assert would fail with an error because request is no longer available 
    (because you are trying to use it outside of the actual request).


- Create a nav bar with logged in user
- Create a logout function


- Create a profile page
- Add the navbar to templates/user/login and templates/user/register


Check username format with regular expressions


- Be able to edit your profile if you're looking at your own profile
    - Check the edit_profile flag on views
    - Add the if/then on the profile view 
    - Create edit form and add bio
    - Modify user model's bio length


- Minor validation changes
    - Create a UserBaseForm class
    - Do a regex for username
    - Put email and username to lower case using signals (install blinker first)


- Write a test for edit on profile page


- Explain how to send email via SES
    - Create an AWS account
    - Create a user on IAM
    - Go to IAM/Policies and attach AmazonSESFullAccess to your user
- Install boto3
- Set credentials in ~/.aws/credentials
    - Important: No quotes around your values
    - `[default]`
        `aws_access_key_id = <your access key>`
        `aws_secret_access_key = <your secret key>`
- Set region in ~/.aws/config (you can set the region on the upper right nav on SES console)
    - `[default]`
    - `region=us-east-1


- Create a mail folder on templates
- Create a base for html and text
- Create register email both text and html
- Add email to utilities/common

Increasing Sending Limits in AWS SES

- We need to generate a confirmation code
    - On user.models add email_confirmed and email_configuration
    - On user.views add a UUID and store on the database


- We need a view to confirm the email
    - Create a confirm route on user.views
    - Register a new user and check on mongodb the code
    - Hit /confirm/<username>/<code> with a bad username and a good username
    - Check on mongodb
    - Hit the correct username again, you should get a 404


- Now send the email when user registers
    - Create a HOSTNAME on (explain dev vs prod)
    - Change the URLs on the email templates
    - Send the email from register views
- We need to skip sending email when running test


- Create a form for it
- Create a view to enter your email and email is sent
- Create a view to enter the new password


- Create a form for it
- Create a view to enter your email and email is sent
- Create a view to enter the new password


- Create a form for it
- Create a view to enter your email and email is sent
- Create a view to enter the new password


Reset Password Tests


- Create a form for it
- Create a view to enter your current password and two repeat passwords

Change Password Tests
Image Uploading Setup
The Imaging Library
The Edit Form and Template for Image
The Edit View for Imaging
Setting up Amazon S3
Section 3 Quiz
3 questions
Section 4: The Relationship Module
Starting the Relationship App
Playing with the Relationship Model
Get Relationship Helper
The Relationship Frontend
Relationship Views
More Work on Relationship Views
Complete Relationship Frontend
Relationship Tests
Relationship Tests Part 2
Adding a Profile Image
The Friends Sidebar
The Friends Page
Reusable Follow Button
Relationship Emails
Section 4 Quiz
3 questions
Section 5: The Feed Module
Introduction to the Fan Out pattern
The Feed Model
Adding the Feed Form to Profile View
Feed Views
Feed Process Message
Feed Message Template
Messages in Profile Views
The Feed Home
Feed Images - Model, Form, Views
Feed images - Resizing, Templates
Feed Timestamp - Milliseconds
Feed Comments - Model and Views
Feed Comments - Templates
Comment Cleanup - Adding Likes
Only See Friend's Posts
Don't Distribute to Blocked Users
Feed Tests - Part 1
Feed Tests - Part 2
The New Homepage
Section 5 Quiz
3 questions
Section 6: Final Project
Final Project

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Instructor Biography

Jorge Escobar, Technologist, entrepreneur and open source fanatic

From Zero is an educational project created by Jorge Escobar, a technologist, entrepreneur and open source fanatic with more than 15 years of experience in the development of web applications in New York City.

Jorge has worked in well established companies like Yahoo!, Univision and MongoDB and has also been the technical founding member of various successful tech startups that have received multiple rounds of venture capital.

The biggest problem Jorge has experienced during his career is finding well rounded developers and he interviewed hundreds of them for positions in the teams he was leading. A constant pattern (no matter if candidates came from a good university or had a few years of experience) was the lack of practical, real world knowledge.

That’s why Jorge created From Zero, an educational project that would address those practical knowledge issues through training that builds hands-on experience and equip students with the tools required to be successful in today’s technology business needs.

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