How to Build a REST API With Flask and Postgres Database
Application Programming Interfaces (APIs) are a critical part of building and connecting different systems, allowing your applications to communicate and exchange data with other services.
While backend development involves more than just writing APIs — it also covers writing server-side business logic, designing efficient system architectures, and other key functions, read on to learn how to build a simple CRUD REST API with Flask (a lightweight Python framework), and Postgres database.
Using Flask to Build Backend APIs
Flaskis a lightweightPython frameworkthat provides a number of features to simplify writing backend APIs for web clients written using different technologies such as React and Angular.
you’re able to find this project’s source code in thisGitHub repository.
This guide will walk you through writing aREST API that implements the four CRUD operations: create, read, update, and delete to manage user data stored in a Postgres database.
Set Up a Postgres Database
To get started, head over toElephantSQL, a cloud-based database hosting solution that provides a platform to create and manage Postgres databases on the cloud, sign up, and log in to your account’s overview page.
Click theCreate New Instancebutton to create a new instance for your application.
Provide the name of your instance and select the free plan, and finally select the region where the instance will be hosted to finish the setup process.
Once the instance is created, navigate to the settings page and copy thedatabase URL, you will use it to establish a connection with the database.
Set Up a Flask Server
On your terminal, create a project folder, and change the current directory to that new folder.
Before installing Flask, confirm that you are running Python version 3.6+ on your machine. If not, you need to install the latestPythonversion.
Afterward, installvirtualenv, to create an isolated virtual development environment.
Next, run the command below to create a virtual environment.
Finally, activate the virtual environment.
Install the Required Packages
In the root directory of your project folder, create arequirements.txtfile and add these packages.
Next, install the packages.
Thepsycopg2-binaryis a Python library that acts as a middleware, to allow you to establish connections with your Postgres database and perform various database operations.
Lastly, create a.envfile and paste your database URL.
Create the Flask Server
Finally, create anapp.pyfile in the root directory, and add the code below.
This code sets up an instance of the Flask application. It then creates a connection to the database specified in the URL string and lastly, sets up a home route that returns a string as a response.
Create the REST API Enabling CRUD Operations
Now, build the REST API that implements the four CRUD operations.
Create a Demo Table
Create a user table within the database.
In the app.py file, add the code below.
1. Define the POST Method
Create the post route to add data.
2. Define the GET Method
Define two get routes: one, to retrieve all the data in the database, and two, to retrieve specific data from the database based on the ID.
3. Define the PUT Method
Create the put route to update the stored data in the database.
4. Define the DELETE Method
Implement the delete route to delete the stored data of a specific user in the database.
Writing REST APIs With Flask
This guide demonstrates how to use Flask and Postgres to build a simple CRUD REST API alongside, how to establish a database connection and execute different SQL queries to read and write data to a database. You can now create a simple REST API that can handle the four CRUD operations required in any web application.
Whether you are building a simple blog or a complex web application, Flask and Postgres offer powerful features and capabilities required to create a robust backend system. Alternatively, you’re able to make use of other technologies like FastAPI and MongoDB to build RESTful APIs.
Get a bare-bones, auto-documented API up and running in no time with this combination of useful tools.
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