Flask Tutorial

Content provided by experienced developers based on the suggestions/questions from the audience. This initiative aims to provide Free/Allways up-to-date programming tutorials - Read the Manifest.

How it works

• Access the existing content
• Open a new issue to get an answer related to an existing topic
• Open a new issue to open a new tutorial topic
• Answers will be provided by experienced contributors
• For Support chat with AppSeed team

Topics

• What is Flask
• Install Flask
• A minimal Flask application
• Flask Project Structure - a few options
• (WIP) Flask Bootstrap Sample - a simple project built with Bootstrap
• (WIP) Jinja Template - how to render HTML pages efficiently

What is Flask

:point_right: Flask is a lightweight web application framework. It is designed to make getting started quick and easy, with the ability to scale up to complex applications. Compared to Django, Flask provides a lightweight codebase and more freedom to the developer.

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Install Flask

:point_right: The easiest way to install Flask is to use PIP the official package-management tool.

$ pip install Flask

How to check Flask version

Open a Python console (type python in terminal) and check the installed version as below:

>> import flask
>> flask.__version__
'1.1.2' 
>>>

In this case the installed version is 1.1.2

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A minimal App

:point_right: Open a terminal and install Flask (if not already installed) using PIP:

$ pip install Flask

Use your preferred editor to create a file called hello.py with this content:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return f'My first Flask!'

Save the file and start the app:

$ env FLASK_APP=hello.py flask run
 * Serving Flask app "hello"
 * Running on http://127.0.0.1:5000/

Above commnand does two things:

• Set the FLASK_APP variable (required by Flask)
• Execute our code with flask run command

By visiting the app in the browser localhost:5000 we should see My first Flask! message.

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Flask Project Structure

:point_right: Being such a lightweight framework, Flask comes with great flexibility regarding the codebase structure of a project. We can use a single file and drop all the code or split the app logic in more files and directories. All variants works but we migth have issues once our project is getting bigger and migth become unreadable for others.

Well, this section presents a few options to keep in mind when we start a Flask project.

:link: Read more: Flask Project Structure: Single File, Isolated App, Blueprints

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Flask Bootstrap Sample

:point_right: We can use the information learned in the previous sections and build from scratch a simple Flask project on top of a modern Bootstrap UI Kit.

:link: Read more: Flask Bootstrap Sample

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Jinja Template

:point_right: Jinja is a modern and designer-friendly templating language for Python, modelled after Django's templates. It is a text-based template language and thus can be used to generate any markup as well as source code.

:link: Read more: Jinja Template

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Flask Tutorial - Free/Allways up-to-date Flask-related content | by AppSeed.