Takatomo Honda - Flask Web Development from Scratch: Introduction to Developing Web Applications with Python

Flask is a lightweight web application framework with Python.

The Flask feature allows applications to be created in a single file. This is called a microframework. On top of that, it has the scalability to build large applications.

This book is about building applications from scratch. I wrote it so that you can learn all the necessary technologies.

It is based on the experience of actually operating the application developed in Flask. I think there are a wide range of situations where the knowledge obtained here can be applied.

The following points have been made into a policy for the organization of this book.

• Read through and cover the basics of creating web applications with Flask
• Finally, youll have a working blog application
• Organized into one chapter on one topic for future reference

Heres my system environment for reference.

• Python: 3.6.3

Sample code is available at:

https://github.com/chaingng/flask_tutorial_en

We would appreciate it if you could send us any typos or feedback. We will update as much as possible.

takatomo.honda.0103@gmail.com

In this book, you create a blog application from scratch. The completed image is as follows:

When you access the top page, the login screen appears.

After you enter your login ID and password, the blog list screen appears.

Click New Post to open the Post screen and create a new article.

Click an article from the blog list screen to display the article details. You can also edit and delete articles from this screen.

If you press the edit button, you can edit the article.

Press the delete button to delete the article.

On latest version of MacOS, Python is installed by default. If you type python --version and the version information appears, you dont need to install it.

If not, install it using the brew command.

If you dont see the version information after typing brew --version, install brew as follows:

Install the Xcode command-line tools.

Install brew.

Verify that brew is installed.

Finally, install python using brew.

On Linux, python is also a standard installation. If not, install it as follows:.

If python --version displays version information, the installation is successful.

pip is a package management system for managing external packages in Python. With pip, you can easily install and use useful packages, including Flask itself, in your applications.

In Python 3.4 and later, pip is installed by default, so no installation is necessary.

If not, you can install it by running the following command:

Type pip --version and the version number is displayed.

Install Flask using the pip described in the previous chapter.

Make a file named hello.py with the following contents:

From the console, type:

The application is now up and running. Go to http://127.0.0.1:5000/.

If it looks like this, it is successful.

You have now created a Flask application with just one file.

Next, youll create a blog application in Flask. Create a folder for the application. Name it application.

Pipenv is a library that allows you to automatically create your own environment (Virtual environments) for each project and manage packages for each virtual environment.

In particular, we used the pip command to install and manage python packages on an entire PC. Pipenv allows you to create your own environment for each project (In other words, for each folder you create).

Typically, if you have multiple projects on one machine, it is difficult to separate the environments for each project.

On the other hand, Pipenv allows you to create your own environment without affecting other projects.

To install Pipenv, run the following command:

Type pipenv --version and the version number will indicate a successful installation.

Now that you have Pipenv installed, Ill use it all from now on without using pip.

Then go to the application folder you created earlier and execute the following command:

Now, under the application folder, you have a dedicated virtual environment for projects running Python3.

At the same time, a file named Pipfile/Pipfile.lock is created that contains the package information.

Lets actually go into a virtual environment.