Building CRUD APIs with Flask and SQLAlchemy

Creating a robust and scalable RESTful API is a fundamental task for backend developers. Python’s Flask microframework, when combined with SQLAlchemy (an Object Relational Mapper, or ORM), provides a clean and efficient way to build CRUD (Create, Read, Update, Delete) APIs. In this blog, we’ll walk through how to build a simple CRUD API using Flask and SQLAlchemy.


What You’ll Need

Before we begin, make sure you have the following installed:

Python (3.x)

Flask

Flask-SQLAlchemy

You can install the required packages using pip:


bash

Copy

Edit

pip install Flask Flask-SQLAlchemy

Setting Up the Flask App

Let’s start by creating a basic Flask application:


python

Copy

Edit

from flask import Flask, request, jsonify

from flask_sqlalchemy import SQLAlchemy


app = Flask(__name__)

app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///users.db'

app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False


db = SQLAlchemy(app)

We’ve configured Flask to use a SQLite database for simplicity, but SQLAlchemy supports multiple databases like MySQL and PostgreSQL.


Creating the Model

We’ll define a User model with fields id, name, and email.


python

Copy

Edit

class User(db.Model):

    id = db.Column(db.Integer, primary_key=True)

    name = db.Column(db.String(100), nullable=False)

    email = db.Column(db.String(100), unique=True, nullable=False)

Now, initialize the database:


python

Copy

Edit

with app.app_context():

    db.create_all()

Building CRUD Endpoints

Let’s now create routes to perform the basic CRUD operations.


Create a User (POST)

python

Copy

Edit

@app.route('/users', methods=['POST'])

def create_user():

    data = request.get_json()

    new_user = User(name=data['name'], email=data['email'])

    db.session.add(new_user)

    db.session.commit()

    return jsonify({'message': 'User created successfully!'}), 201

Read All Users (GET)

python

Copy

Edit

@app.route('/users', methods=['GET'])

def get_users():

    users = User.query.all()

    return jsonify([{'id': user.id, 'name': user.name, 'email': user.email} for user in users])

Read Single User (GET)

python

Copy

Edit

@app.route('/users/<int:id>', methods=['GET'])

def get_user(id):

    user = User.query.get_or_404(id)

    return jsonify({'id': user.id, 'name': user.name, 'email': user.email})

Update a User (PUT)

python

Copy

Edit

@app.route('/users/<int:id>', methods=['PUT'])

def update_user(id):

    user = User.query.get_or_404(id)

    data = request.get_json()

    user.name = data.get('name', user.name)

    user.email = data.get('email', user.email)

    db.session.commit()

    return jsonify({'message': 'User updated successfully!'})

Delete a User (DELETE)

python

Copy

Edit

@app.route('/users/<int:id>', methods=['DELETE'])

def delete_user(id):

    user = User.query.get_or_404(id)

    db.session.delete(user)

    db.session.commit()

    return jsonify({'message': 'User deleted successfully!'})

Running the App

Run your Flask app with:


bash

Copy

Edit

python app.py

Make sure your file is named app.py or adjust accordingly.


Conclusion

Building CRUD APIs with Flask and SQLAlchemy is straightforward and powerful. SQLAlchemy’s ORM capabilities abstract the complexity of direct SQL queries, and Flask provides a lightweight structure to build and scale your API. This setup forms a solid foundation for real-world applications, which you can enhance further with authentication, pagination, and input validation.

Learn FullStack Python Training
Read More : Fullstack Python: Implementing GraphQL APIs in Flask

Visit Our IHUB Talent Training Institute in Hyderabad

Comments

Post a Comment

Popular posts from this blog

How to Use Tosca's Test Configuration Parameters

Tosca by Tricentis is a powerful model-based test automation tool widely used in enterprise environments for end-to-end testing. One of its most useful features is Test Configuration Parameters (TCPs), which provide flexibility and control in managing test execution. TCPs enable testers to create reusable test cases by passing dynamic values without hardcoding them. This significantly enhances test maintenance, scalability, and efficiency. In this blog, we’ll explore what Test Configuration Parameters are, how to create and use them, and the best practices to follow when working with TCPs in Tosca. What Are Test Configuration Parameters? Test Configuration Parameters are custom-defined key-value pairs that can be associated with test cases, test case folders, or execution lists in Tosca. They help manage configuration data such as environment URLs, browser types, credentials, or any other variable data that may differ across test runs. By using TCPs, you can avoid duplicating test case...
Read more

Installing Java and Eclipse IDE for Selenium Automation

Selenium is one of the most popular open-source tools for automating web applications for testing purposes. To begin your journey with Selenium automation using Java, you need to first install Java Development Kit (JDK) and an Integrated Development Environment (IDE) like Eclipse. This blog will walk you through the step-by-step process of setting up Java and Eclipse IDE on your system, preparing you to start writing and executing Selenium scripts. Step 1: Install Java Development Kit (JDK) What is JDK? The Java Development Kit (JDK) provides the tools required to develop and run Java applications. It includes the Java Runtime Environment (JRE), compiler (javac), and various development tools. How to Install JDK: Download JDK: Visit the official Oracle website or use an open-source version like AdoptOpenJDK. Download the latest stable version (preferably JDK 11 or later). Install JDK: Run the downloaded installer and follow the installation wizard. During installation, note the install...
Read more

How Flutter Works Behind the Scenes

Flutter, Google’s open-source UI toolkit, has rapidly become a popular choice for building beautiful, natively compiled applications for mobile, web, and desktop from a single codebase. But have you ever wondered how Flutter works behind the scenes to deliver such smooth and performant apps? In this blog, we’ll dive into Flutter’s architecture and explain the key components that make it tick. What is Flutter? At its core, Flutter allows developers to write code in the Dart programming language, which is then compiled to native machine code. Flutter doesn’t rely on native UI components; instead, it draws every pixel on the screen using its own rendering engine. This unique approach gives developers full control over the UI and enables consistent behavior across platforms. Flutter’s Architecture: The Big Picture Flutter’s architecture can be broken down into three main layers: Dart Framework Flutter Engine Platform-Specific Embedder 1. Dart Framework The Dart framework is what developers...
Read more