Flask Tutorial

Flask is a web framework that allows you to build web applications using Python. It is a lightweight framework that is easy to learn and use. In this tutorial, we will cover the basics of Flask and see how to build a basic web application using it.

Syntax

To get started with Flask, you need to install it using pip. Once installed, you can create a new Flask application as follows:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def index():
    return 'Hello, World!'

To run the application, you can use the following command:

flask run

This will start a development server that will serve the application on http://localhost:5000.

Example

Let's create a simple web application that allows you to enter a name and displays a greeting message.

from flask import Flask, request

app = Flask(__name__)

@app.route('/')
def index():
    return '''
        <form method="POST" action="/greet">
            <label for="name">Enter your name:</label>
            <input type="text" name="name" id="name" required>
            <button type="submit">Greet</button>
        </form>
    '''

@app.route('/greet', methods=['POST'])
def greet():
    name = request.form['name']
    return f'Hello, {name}!'

Output

When you run the above application and visit http://localhost:5000, you will see a form that allows you to enter your name. When you submit the form, you will be greeted with a message that says "Hello, [your name]!".

Explanation

The above application consists of two routes:

• The / route displays a form that allows you to enter your name.
• The /greet route handles the form submission and displays a greeting message.

When you submit the form, the request object is used to retrieve the value of the name input field. This value is then used to generate the greeting message.

Use

Flask can be used to build a variety of web applications, including:

• RESTful APIs
• Web dashboards
• E-commerce websites
• Social networking sites

Important Points

• Flask is a lightweight web framework that is easy to learn and use.
• Flask uses a simple syntax that is similar to Python.
• Flask is flexible and can be used to build a wide range of web applications.

Summary

In this tutorial, we covered the basics of Flask and saw how to build a simple web application using it. We also saw some of the important points to keep in mind when using Flask. With this knowledge, you should be able to start building your own web applications using Flask.