How to perform common Flask operations in Python?

Flask is a popular web framework for building web applications in Python. Here are some of the most common Flask operations:

1. Creating a Flask app: To create a Flask app in Python, you first need to install the Flask library using pip. Then, you can create a new Flask app with the following code:

from flask import Flask

app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello, World!"

1. Routing in Flask: Flask uses routing to map URL patterns to view functions that handle requests. You can define a route using the @app.route() decorator. For example:

@app.route("/users/<username>")
def show_user_profile(username):
    return "User %s" % username

1. Templates in Flask: Flask uses the Jinja2 templating engine to generate dynamic HTML content. You can create a template using the render_template() function. For example:

from flask import render_template

@app.route("/")
def index():
    return render_template("index.html", title="Home")

1. Forms in Flask: Flask provides support for handling HTML forms. You can create a form using the Flask-WTF library. For example:

from flask_wtf import FlaskForm
from wtforms import StringField, SubmitField
from wtforms.validators import DataRequired

class ContactForm(FlaskForm):
    name = StringField("Name", validators=[DataRequired()])
    email = StringField("Email", validators=[DataRequired()])
    message = StringField("Message", validators=[DataRequired()])
    submit = SubmitField("Send")

1. Database operations in Flask: Flask supports a variety of databases including SQLite, MySQL, and PostgreSQL. You can use the Flask-SQLAlchemy library to perform database operations. For example:

from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'
db = SQLAlchemy(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)

    def __repr__(self):
        return '<User %r>' % self.username

These are just a few examples of common Flask operations in Python. Flask provides many more features and extensions, so it’s a good idea to