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Learning Flask Framework

Learning Flask Framework

4.5 (2)
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Learning Flask Framework

Learning Flask Framework

4.5 (2)

Overview of this book

Flask is a small and powerful web development framework for Python. It does not presume or force a developer to use a particular tool or library. Flask supports extensions that can add application features as if they were implemented in Flask itself. Flask’s main task is to build web applications quickly and with less code. With its lightweight and efficient web development framework, Flask combines rapid development and clean, simple design. This book will take you through the basics of learning how to apply your knowledge of Python to the web. Starting with the creation of a “Hello world” Flask app, you will be introduced to the most common Flask APIs and Flask’s interactive debugger. You will learn how to store and retrieve blog posts from a relational database using an ORM and also to map URLs to views. Furthermore, you will walk through template blocks, inheritance, file uploads, and static assets. You will learn to authenticate users, build log in/log out functionality, and add an administrative dashboard for the blog. Moving on, you will discover how to make Ajax requests from the template and see how the Mock library can simplify testing complex interactions. Finally, you will learn to deploy Flask applications securely and in an automated, repeatable manner, and explore some of the most popular Flask resources on the web.
Table of Contents (12 chapters)
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Preface
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Free Chapter
1
1. Creating Your First Flask Application
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1. Creating Your First Flask Application
What is Flask?
Setting up a development environment
Installing Python packages
Creating your first Flask app
Introducing the blog project
Summary
2
2. Relational Databases with SQLAlchemy
2. Relational Databases with SQLAlchemy
Why use a relational database?
Introducing SQLAlchemy
Creating the Entry model
Retrieving blog entries
Building a tagging system
Making changes to the schema
Summary
3
3. Templates and Views
3. Templates and Views
Introducing Jinja2
Creating a base template for the blog
Creating a URL scheme
Adding pagination links
Enhancing the blog app
Summary
4
4. Forms and Validation
4. Forms and Validation
Getting started with WTForms
Using flash messages
Saving and modifying tags on posts
Serving static files
Summary
5
5. Authenticating Users
5. Authenticating Users
Creating a user model
Installing Flask-Login
Creating user objects
Login and logout views
Accessing the current user
Restricting access to views
Sessions
Summary
6
6. Building an Administrative Dashboard
6. Building an Administrative Dashboard
Installing Flask-Admin
Exposing models through the Admin
Managing static assets via the Admin
Securing the admin website
Reading more
Summary
7
7. AJAX and RESTful APIs
7. AJAX and RESTful APIs
Creating a comment model
Installing Flask-Restless
Creating comments using AJAX
Loading comments using AJAX
Reading more
Summary
8
8. Testing Flask Apps
8. Testing Flask Apps
Unit testing
Flask and unit testing
Test-friendly configuration
Mocking objects
Logging and error reporting
Read more
Summary
9
9. Excellent Extensions
9. Excellent Extensions
SeaSurf and CSRF protection of forms
Creating Atom feeds
Syntax highlighting using Pygments
Simple editing with Markdown
Caching with Flask-Cache and Redis
Creating secure, stable versions of your site by creating static content
Asynchronous tasks with Celery
Creating command line instructions with Flask-script
References
Summary
10
10. Deploying Your Application
10. Deploying Your Application
Running Flask with a WSGI server
Securing your site with SSL
Automating deployment using Ansible
Read more
Summary
11
Index
Index

Installing Python packages

Now that you have ensured that Python is installed correctly, we will install some popular Python packages that will be used over the course of this book.

We will be installing these packages system-wide but, once they are installed, we will be working exclusively in virtual environments.

Installing pip

The de-facto Python package installer is pip . We will use it throughout the book to install Flask and other third-party libraries.

If you already have setuptools installed, you can install pip by simply running the following command:

$ sudo easy_install pip

After completing the installation, verify that pip is installed correctly:

$ pip --version
pip 1.2.1 from /usr/lib/python2.7/site-packages/pip-1.2.1-py2.7.egg (python 2.7)

The version numbers are likely to change, so for a definitive guide please consult the official instructions, which can be found at http://www.pip-installer.org/en/latest/installing.html.

Installing virtualenv

Once pip is installed, we can proceed to install the most important tool in any Python developer's toolkit: virtualenv. Virtualenv makes it easy to produce isolated Python environments, complete with their own copies of system and third-party packages.

Why use virtualenv?

Virtualenv solves a number of problems related to package management. Imagine you have an old application that was built using a very early version of Flask, and you would like to build a new project using the most-recent version of Flask. If Flask was installed system-wide, you was be forced to either upgrade your old project or write your new project against the old Flask. If both projects were using virtualenv, then each could run its own version of Flask, with no conflicts or issues.

Virtualenv makes it easy to control which versions of the third-party package is used by your project.

Another consideration is that installing packages system-wide generally requires elevated privileges (sudo pip install foo). By using virtualenvs, you can create Python environments and install packages as a regular user. This is especially useful if you are deploying to a shared hosting environment or are in a situation where you do not have administrator privileges.

Installing virtualenv with pip

We will use pip to install virtualenv; since it is a standard Python package, it can be installed just like any other Python package. To ensure that virtualenv is installed system-wide, run the following command (it requires elevated privileges):

$ sudo pip install virtualenv
$ virtualenv --version
1.10.1

The version numbers are likely to change, so for a definitive guide please consult the official instructions at http://virtualenv.org.

End of Section 4
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