Flask Tutorial [1]

  • Thu, Jun 2, 2022
  • 3-minute read

If you want to learn flask by developing a project by yourself, this tutorial will be helpful to you.

This tutorial covered with

  1. Flask introduction
  2. How Flask works
  3. How to use Flask Plugin
    • Flask-SQLAlchemy
    • Flask-WTF
    • Flask-Bootstrap
  4. Install a Python 3.6 up interpreter

And we are going to use these things to create a simple posting web application

Prerequired

  1. Basic Python knowledges
  2. Basic shell commands (cd, mkdir, rm….)
  3. Basic Object Oriented Program knowledges
  4. Maybe some HTML basis

Flask Introduction

Flask is a web framework written in Python. And it’s micro framework, which means it doesn’t have too many out-of-the-box features, such as ORM, Form validation functions, etc…. Everything is depending on what you want to use. Compare to Django (Another Python web framework, which has a lot built-in funtionalities.), Flask is more freedom. And you can also find many useful plugin of Flask, like Flask-SQLAlchemy, which intergrates SQLAlchemy into Flask.

But how can we get started. Let’s dive into the next part.

Set the developement environment for Flask

We have to set an virtual environment for our project first.

Why we need to use the virtual environment? Well, this is because if we just pip install something without any setup beforehand, it will install the packages into global environment which makes us hard to controll our packages version in each project also it can lead to the dirty global pip environemnt.

1. Create a virutal environment

So…. how can we create a virtual environment?

  • If you are on Windows, just go to the path where you want to develop the project and type python -m venv venv in terminal of that path.

  • If you are on Linux or MacOS, you can just go into the project folder and type python3 -m venv venv

   

2. Activate the virtual environment

And after we made a virutal environment, you will see a folder called venv but now it is not usable because we have to activate it.

  • Windows: Type \venv\Scripts\activate to activate the environment

  • Linux & MacOS: Type source ./venv/bin/activate

After doing so, you will see something like the text I framed in front of your promt. (Don’t be worried if yours shows different)

3. Install Flask

After activated the virtual environment, we can install the packages and them will just be installed inside this virtual environemnt.

Type pip install flask inside this virtual environment

Then we create a file called app.py inside this directory

And we can start to develop our web application in this file

Add these codes to file

from flask import Flask

app = Flask(__name__)

@app.route('/')
def index():
    return "<h1>Hello My First Flask Web App !!!</h1>"

And type flask run in the project root directory

And you can go to localhost:5000 in your browser