Building a Python Flask Web Application from Scratch: Part 1 – Starting Out

In this tutorial, we will be learning how to create a web application using Python Flask from scratch. Flask is a lightweight web application framework for Python that allows you to easily build web applications.

In this first part of the tutorial, we will be focusing on getting started with Flask, setting up the necessary environment, and creating a basic web application.

Step 1: Install Flask
To get started with Flask, you will need to have Python installed on your system. You can download Python from the official website (https://www.python.org/).

Once you have Python installed, you can install Flask using pip, which is Python’s package installer. Open your command prompt or terminal and run the following command:

pip install Flask

This will install Flask on your system. You can verify that Flask has been installed by running the following command:

flask --version

Step 2: Setting up the Flask environment
Now that you have Flask installed, you can create a new directory for your Flask project. Navigate to the directory where you want to create your project and run the following command to create a new virtual environment:

python -m venv venv

This will create a new virtual environment in a directory called venv. Next, activate the virtual environment by running the following command:

On Windows:

venvScriptsactivate

On Mac or Linux:

source venv/bin/activate

Step 3: Creating a basic Flask application
Now that we have set up our Flask environment, we can create a basic Flask application. Create a new Python file in your project directory and name it app.py.

In app.py, we will create a simple Flask application that displays a message when you visit the home page. Here is the code for the basic Flask application:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def home():
    return 'Hello, Flask!'

if __name__ == '__main__':
    app.run()

This code creates a new Flask application that responds with the message ‘Hello, Flask!’ when you visit the home page.

Step 4: Running the Flask application
To run the Flask application, simply navigate to your project directory in the command prompt or terminal and run the following command:

python app.py

This will start the Flask development server and you will see a message that the server is running. Open your web browser and go to http://127.0.0.1:5000/ to see your Flask application in action.

Congratulations! You have successfully created a basic Flask application from scratch. In the next part of the tutorial, we will learn how to create more complex web applications using Flask. Stay tuned for Part 2!