Top Python Flask Interview Questions (2024)
A Python module that makes it simple to create web applications is called Flask. Its core is compact and simple to extend; it's a microframework that has lots of features, such as url routing and a template engine.
What is Flask and how is it different from Django?
How to create a Flask application?
How to create a route in Flask?
What is Flask-WTF and how to use it?
How to handle errors in Flask?
What is Flask-SQLAlchemy and how to implement in Flask?
How to implement authentication and authorization in Flask?
What is Flask-RESTful and how to use it?
How to deploy a Flask application to production?
How to use database in Flask application?
How to implement caching in Flask?
How to do file uploads in Flask?
What is the difference between Flask's app.run() and a production-ready web server like Gunicorn or uWSGI?
Q: What is Flask and how is it different from Django?
Ans:
A Python module that makes it simple to create web applications is called Flask. Its core is compact and simple to extend; it's a microframework that has lots of features, such as url routing and a template engine. Because it is lightweight, modular, and flexible, and because developers can pick and choose which components to utilize, it differs from Django.
Q: How to create a Flask application?
Ans:
Users must create a new Python file and import the Flask module in order to create a Flask application. The next step is to describe the routes and views and create a new instance of the Flask class.
Refer steps to setup and install Python Flak application
Q: How to create a route in Flask?
Ans:
In Flask, users must use the @app.route() decorator and the URL of the route we
wish to
construct in order to create one. Define the function that will be called when the route is
accessed.
Refer implementation code for Python Restful API's
Q: What is Flask-WTF and how to use it?
Ans:
The Flask-WTF extension allows for integration with the WTForms library. In your Flask application, it enables simple form creation and validation. Users must create a new class that inherits from FlaskForm and import it from flask wtf in order to use it.
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Q: How to handle errors in Flask?
Ans:
The @app.errorhandler() decorator in Flask allows to specify error handlers for
particular HTTP
status codes. A generic error handler can also be defined to deal with any exception that arises
in the application.
Q: What is Flask-SQLAlchemy and how to implement in Flask?
Ans:
A Flask extension that integrates with the SQLAlchemy ORM is called Flask-SQLAlchemy. It makes working with databases in Flask application simple. First we need to create a SQLAlchemy class new instance and define database models as classes.
Q: How to implement authentication and authorization in Flask?
Ans:
Flask offers a number of methods for implementing authentication and authorization, including the use of Flask-Login and Flask-JWT. Using session management and unique decorators, we can also design our own authentication and authorization logic.
Q: What is Flask-RESTful and how to use it?
Ans:
Flask-RESTful is an add-on for Flask that makes it simple to create RESTful APIs. It gives us a collection of classes to utilize when defining resources and handles the routing, input parsing, and output formatting.
Refer implementation code for Python CRUD Restful API's
Q: How to deploy a Flask application to production?
Ans:
A Flask application can be put into production in a number of methods, such as using a hosting service on Heroku or AWS or putting it on our own server using a WSGI server like Gunicorn or uWSGI.
Q: How to use database in Flask application?
Ans:
We can use database in Flask by using an ORM like SQLAlchemy or a raw SQL library like Psycopg2. And create database models and its classes, to communicate with database.
Q: How to implement caching in Flask?
Ans:
With an extension like Flask-Caching or Flask-Cache, we can implement caching in Flask. These extensions offer a straightforward user interface for caching function output, view output, or even whole pages.
Q: How to do file uploads in Flask?
Ans:
When handling file uploads in Flask, user can retrieve the uploaded file data by using the
request.files object. The file can subsequently be processed, saved to disc, or
kept in a
database.
Q: What is the difference between Flask's app.run() and a production-ready web server like
Gunicorn or uWSGI?
Ans:
- The built-in development web server
app.run()for Flask is only intended for testing and is not advised for use in production environments. It is a single-threaded, non-scalable server that isn't made to deal with a lot of traffic or numerous requests running at once. Also, the server is not security-optimized and shouldn't be accessible via the open internet. - Whereas, Gunicorn and uWSGI are production-ready web servers that are built to manage heavy traffic and numerous concurrent requests. These servers are scalable, multi-threaded, and security-focused. Also, they can manage many processes, which enables them to utilize all of the hardware resources.
- Use a production-ready web server, such as Gunicorn or uWSGI, for deploying a Flask application. These servers offer superior performance, scalability, and security when configured to work with Flask. They can also be linked with other tools and services, such as load balancers and monitoring tools, and they provide improved control over the deployment process.