Python Programming Blueprints: Build nine projects by leveraging powerful frameworks such as Flask, Nameko, and Django

456 Pages·2017·5.93 MB·english

by  Daniel Furtado

Python Programming
Blueprints
Build nine projects by leveraging powerful frameworks such
as Flask, Nameko, and Django
Daniel Furtado
Marcus Pennington
BIRMINGHAM - MUMBAI
Python Programming Blueprints
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First published: February 2018
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I dedicate this book to my family—my sister, Camila, my mother, Silvia, and my father, Simão,
who have done everything in their power to help me achieve all my dreams. There are no words
to express how grateful and lucky I feel for being their child.
To my lovely Maria, who every day gives me strength, encouragement, inspiration, and love. I
wouldn't have made it without you. I love you! Also, to my loyal French bulldog friends, Edit
and Ella.
–Daniel Furtado
My parents, Dawn and Robert, who over my lifetime have always pushed me to do my best.
They instilled in me the ability to accomplish anything I put my mind to.
Fabrizio Romano for convincing me to contribute to this book. He is the greatest mentor an
aspiring developer could ask for.
And finally, my partner, Emily, for always being there for me.
–Marcus Pennington
Contributors
About the authors
Daniel Furtado is a software developer with over 20 years of experience in different
technologies such as Python, C, .NET, C#, and JavaScript. He started programming at the
age of 13 on his ZX Spectrum.
He joined the Bioinformatics Laboratory of the Human Cancer Genome Project in Brazil,
where he developed web applications and tools in Perl and Python to help researchers
analyze data. He has never stopped developing in Python ever since.
Daniel has worked on various open source projects; the latest one is a PyTerrier web micro-
framework.
Marcus Pennington started his journey into computer science at Highams Park Sixth Form
College where he took a Cisco CCNA course.
He then went to the University of Hertfordshire, where he graduated with a degree in
Computer Science with Artificial Intelligence. Since then, he has had the privilege of
working with some of the best developers and learning the benefits and pitfalls of many of
the software practices we use today.
He has a passion for writing clean, cohesive, and beautiful code.
I would like to acknowledge Tom Viner for giving my chapters a thorough review; his
insights not only improved the quality of my chapters but also taught me a great deal.
Julio Trigo, an expert at using PostgreSQL with Python; his knowledge supplemented my
own when creating the database dependency.
Edward Melly, a JavaScript and React craftsman, for reviewing the frontend code in my
chapters.
About the reviewers
Tom Viner is a senior software developer living in London. He has over 10 years of
experience in building web applications and has been using Python and Django for 8 years.
He has special interests in open source software, web security, and Test-driven
development.
Tom has given two conference talks, Testing with two failure seeking missiles: fuzzing
and property based testing and Exploring unit-testing, unittest v pytest: FIGHT!
Tom works for Sohonet in central London and sometimes goes backpacking around the
world.
I would like to thank Marcus Pennington for inviting me to review this book.
Radovan Kavický is the principal data scientist and president at GapData Institute based in
Bratislava, Slovakia, harnessing the power of data and wisdom of economics for public
good.
He has an academic background in macroeconomics and is a consultant and data scientist
by profession.
Radovan is also an instructor at DataCamp and a founder of PyData Bratislava, R <-
Slovakia & SK/CZ Tableau User Group (skczTUG).
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Table of Contents
Preface 1
Chapter 1: Implementing the Weather Application 7
Setting up the environment 8
Core functionality 10
Loading parsers dynamically 10
Creating the application's model 12
Fetching data from the weather website 19
Getting the user's input with ArgumentParser 20
Creating the parser 27
Getting today's weather forecast 29
Adding helper methods 30
Implementing today's weather forecast 32
Getting five- and ten-day weather forecasts 37
Getting the weekend weather forecast 43
Summary 47
Chapter 2: Creating a Remote-Control Application with Spotify 48
Setting up the environment 49
Creating a Spotify app 52
The application's configuration 56
Creating a configuration file 57
Implementing a configuration file reader 58
Authenticating with Spotify's web API 63
Implementing the client credentials flow 64
Implementing the authorization code flow 68
Authorizing our application with authorization code flow 71
Querying Spotify's web API 77
Creating the player 85
Adding menus for albums and track selection 88
Implementing the menu panel 89
Creating the DataManager class 95
Table of Contents
Time to listen to music! 99
Summary 111
Chapter 3: Casting Votes on Twitter 112
Setting up the environment 113
Creating a Twitter application 116
Adding the configuration file 119
Performing authentication 123
Creating the Flask application 124
Creating the application routes 126
Building the Twitter voting application 132
Enhancing our code 137
Summary 152
Chapter 4: Exchange Rates and the Currency Conversion Tool 153
Setting up the environment 154
Creating the API wrapper 161
Adding the database helper class 164
Creating the command line parser 167
Creating the currency enumeration 172
Creating the command line parser 173
Basic validation 177
Adding the application's entry point 179
Testing our application 182
Summary 184
Chapter 5: Building a Web Messenger with Microservices 185
TempMessenger Goals 186
Requirements 186
What is Nameko? 187
RPCs 187
How Nameko uses AMQP 188
RabbitMQ 188
Starting a RabbitMQ container 189
Installing Python requirements 189
Creating your first Nameko microservice 191
Making a call to our service 193
[ ii ]
Table of Contents
Unit-testing a Nameko microservice 193
Exposing HTTP entrypoints 194
Integration testing Nameko microservices 196
Storing messages 197
An introduction to Redis 197
Starting a Redis container 197
Installing the Python Redis client 198
Using Redis 198
Nameko Dependency Providers 199
Adding a Redis Dependency Provider 200
Designing the Client 200
Creating the Dependency Provider 201
Creating our Message Service 202
Putting it all together 203
Saving messages 204
Adding a save message method to our Redis client 204
Adding a save message RPC 205
Retrieving all messages 206
Adding a get all messages method to our Redis client 206
Adding a get all messages RPC 207
Putting it all together 208
Displaying messages in the web browser 208
Adding a Jinja2 Dependency Provider 208
Creating the template renderer 209
Creating our homepage template 210
Creating the Dependency Provider 211
Making a HTML response 211
Putting it all together 212
Sending messages via POST requests 214
Adding a send messages POST request 215
Adding an AJAX POST request in jQuery 216
Expiring messages in Redis 219
Sorting messages 220
Browser polling for messages 222
Polling with JavaScript 223
Summary 225
[ iii ]