20 Python Flask Interview Questions and Answers

Python Flask is a web development framework that is popular for its ease of use and flexibility. If you are applying for a position that involves Python Flask, it is important to be prepared for the interview process. In this article, we will review some of the most common Python Flask interview questions and provide tips on how to answer them.

Python Flask Interview Questions and Answers

Here are 20 commonly asked Python Flask interview questions and answers to prepare you for your interview:

1. What is Flask?

Flask is a web application framework written in Python. It is designed to make getting started quick and easy, with the ability to scale up to complex applications. Flask is also widely used for creating APIs.

2. Can you explain how to install the flask framework in Python?

The flask framework is not part of the standard Python distribution, so you will need to install it separately. The easiest way to do this is using the pip package manager, which you can install with the following command:

pip install flask

Once you have pip installed, you can use it to install flask with the following command:

pip install flask

3. What are some common use cases for Flask?

Flask is a web application framework written in Python. It is a microframework that provides only the essential components of a web application, such as a web server, routing, request and response objects, and template engine. This makes Flask ideal for small projects or for prototyping new ideas. Some common use cases for Flask include building simple web applications, RESTful APIs, and microservices.

4. What’s the best way to create a new application using Flask?

The best way to create a new application using Flask is to use the Flask command line interface. This will allow you to create a new project directory and set up all of the necessary files for your application.

5. How do you define routes in Flask and what are they used for?

Routes are defined in Flask using the @app.route decorator. Routes are used to map URLs to Python functions.

6. Is it possible to pass parameters through an HTTP request using Flask? If yes, then how?

Yes, it is possible to pass parameters through an HTTP request using Flask. You can do this by using the request.args object. This object stores all of the parameters that are passed in through the URL.

7. What is a template in Flask?

A template is a file that contains static data as well as placeholders for dynamic data. When a template is rendered, the placeholders are replaced with the actual values and the resulting document is returned to the user.

8. What does the “app.run()” method do?

The “app.run()” method is used to start the Flask web application. This method will take care of all the necessary steps to get the application up and running, including setting up the development server and loading the application.

9. What is the significance of templates in Flask?

Templates are a key part of Flask applications. They are used to render HTML pages, and can be used to insert data into those pages before they are displayed to the user. This allows for dynamic content to be displayed on a Flask-powered website.

10. How can you make sure that your application remains thread-safe when running with multiple threads?

When running with multiple threads, it is important to make sure that your application remains thread-safe. One way to do this is to use a lock around any code that modifies shared data. This will ensure that only one thread can execute that code at a time, and that other threads will have to wait until the lock is released before they can continue.

11. What is the difference between a session and a cookie in the context of web applications?

A session is a server-side storage mechanism for storing data about a user across multiple requests. A cookie, on the other hand, is a client-side storage mechanism for storing data about a user in a small text file.

12. What’s the best way to provide security in your Flask application?

The best way to provide security in a Flask application is to use a web server gateway interface (WSGI) server. This will allow you to run your Flask application in a more secure environment. Additionally, you should consider using a secure server certificate to encrypt your data.

13. Why should you not run your Flask application under root privileges?

Running a Flask application under root privileges is generally considered to be a bad idea. This is because it can lead to potential security vulnerabilities, since the application will have access to all of the system’s files and resources. It is better to run the application under a non-root user account with limited privileges.

14. What are proxies and why are they useful?

Proxies are essentially intermediary servers that act on behalf of other clients. They can be used for a variety of purposes, such as caching content, filtering traffic, or even anonymizing requests. In the context of Flask, proxies can be used to route requests to the appropriate Flask application instance. This can be useful when you have multiple Flask applications running on the same server and you want to be able to direct traffic to the correct one.

15. What’s the best way to handle logging in a Flask application?

The best way to handle logging in a Flask application is to use the Flask-Login extension. This extension provides a robust set of tools for managing user accounts and permissions, and it makes it easy to add login and logout functionality to your Flask app.

16. What is a class based view in Flask?

A class based view is a view that is defined as a class instead of a function. This allows for more flexibility and organization when creating views.

17. How do you use GET and POST methods in Flask?

The GET and POST methods are used to request data from a server. GET is used to request data from a server, and POST is used to submit data to a server.

18. Can you explain what inheritance is?

Inheritance is a way to form new classes using classes that have already been defined. The new class is called the derived class, and the class it inherits from is called the base class. The derived class inherits all the attributes and methods of the base class, but it can also have its own, unique attributes and methods.

19. What are class variables, instance variables, and local variables?

Class variables are variables that are shared by all instances of a class. Instance variables are variables that are specific to a particular instance of a class. Local variables are variables that are defined within a function and are only accessible within that function.

20. What is the usage of static files in Flask templates?

Static files are used to store images, CSS, JavaScript, and other files that are not specific to a particular Flask template. These files are typically served from a separate server, and are not processed by the Flask template engine.