Why ORM simplifies database access in Flask - See It in Action

Why ORM simplifies database access

📖 Scenario: You are building a simple web app to manage a list of books. Instead of writing raw SQL queries, you want to use an ORM to make database access easier and more readable.

🎯 Goal: Create a Flask app that uses SQLAlchemy ORM to define a Book model, configure the database, add some books, and query them using ORM methods.

📋 What You'll Learn

Define a Book model class with id, title, and author fields

Configure the Flask app to use SQLite database with SQLAlchemy

Add two book entries to the database using ORM

Query all books from the database using ORM and store in a variable

💡 Why This Matters

🌍 Real World

ORMs let developers work with databases using familiar programming language objects instead of writing complex SQL queries. This speeds up development and reduces errors.

💼 Career

Many web development jobs require knowledge of ORMs like SQLAlchemy to efficiently manage database access in Python web apps.

1

Set up Flask app and SQLAlchemy

Create a Flask app instance called app and configure it to use SQLite database at sqlite:///books.db. Then create a SQLAlchemy object called db linked to app.

Flask

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

# Your code here

Need a hint?

Use Flask(__name__) to create the app and set app.config['SQLALCHEMY_DATABASE_URI'] to the SQLite URL.

2

Define the Book model

Define a class called Book that inherits from db.Model. Add three columns: id as an integer primary key, title as a string of max length 100, and author as a string of max length 50.

Flask

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///books.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)

# Define Book model here

Need a hint?

Use db.Column with appropriate types and primary_key=True for id.

3

Add books to the database

Create two Book objects with titles 'The Great Gatsby' by 'F. Scott Fitzgerald' and '1984' by 'George Orwell'. Add them to the database session and commit the session.

Flask

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///books.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)

class Book(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(100))
    author = db.Column(db.String(50))

# Create two Book objects and add to session
# Commit the session

Need a hint?

Create Book instances with the given titles and authors, then add and commit them using db.session.

4

Query all books using ORM

Use Book.query.all() to get all book records from the database and store them in a variable called all_books.

Flask

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///books.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)

class Book(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(100))
    author = db.Column(db.String(50))

book1 = Book(title='The Great Gatsby', author='F. Scott Fitzgerald')
book2 = Book(title='1984', author='George Orwell')
db.session.add(book1)
db.session.add(book2)
db.session.commit()

# Query all books and store in all_books

Need a hint?

Use Book.query.all() to get all records and assign to all_books.