An Introduction to Python Flask Framework for Beginners

Gafureducation

To handle 404 (Not Found) errors in Flask, you can create a custom error handler using the app.errorhandler() decorator. This allows you to return a custom response, such as rendering an error template, when a 404 error occurs. This is a simple example of how to render an HTML template with Flask. Flask’s render_template function also allows you to pass variables to your templates, include other templates, and more. Check out Flask’s documentation for more information on how to use render_template.

  • At its core, Flask facilitates the creation of web applications through a simple yet robust foundation.
  • Profiling tools like Flask-Profiling can help identify performance bottlenecks in your application.
  • Keep track of your Python dependencies using a requirements.txt file.

It also ensures that, even though you need that information to run the application, it never shows up as a hardcoded value in source control. Note that a wide variety of SQL database management systems can be used with flask-sqlalchemy, as long as the DBMS has an intermediary that follows the DBAPI-2 standard. In this example, I’ll use PostgreSQL (mainly because I’ve used it a lot), so the intermediary to talk to the Postgres database is the psycopg2 package. Make sure psycopg2 is installed in your environment and include it in the list of required packages in setup.py. You don’t have to do anything else with it; flask-sqlalchemy will recognize Postgres from the database URL.

An introduction to the Flask Python web app framework

You’ll choose from one of the many data centers available around the world for application hosting at Kinsta. Make note of your selection because you will want to use the same one when creating your database. Login to your MyKinsta dashboard and make sure you have authorized Kinsta to access your Git service provider. Follow the steps to add an application, selecting the repository and branch on the Git host where Kinsta will find this Flask project code. Make sure you add a database user with permissions to access the database and create tables. You can explore the benefits of using Flask for web app development by creating a Python web app using Flask.

With an origin story that’s as quirky as its approach (yes, it sprouted from an April Fool’s gag!), Flask wasn’t born out of necessity but rather from the spirit of creativity. It’s the little framework – starting as a straightforward wrapper around Werkzeug and Jinja – turned into a favorite among developers who prioritize flask developer agility and precision. This starts a local development server, which you can access through your web browser. For a basic application, you can define a simple route that returns a message. Flask’s minimalistic and straightforward approach makes it an excellent choice for quickly setting up a web application.

Frontend Development vs Backend Development

In the above example, we have a template file named “index.html” that can be found in the “templates” folder. The render_template function takes the template name as the first argument and any additional variables as keyword arguments. In this case, we pass the variable “name” with the value “John” to the template. In the above example, we have defined routes for the root URL (“/”), an about page (“/about”), a dynamic user profile page (“/user/”), and a login page (“/login”).

  • There are many extensions provided by the
    community that make adding new functionality easy.
  • First create a directory to work in (something like flask_todo is a fine directory name) then install the flask package.
  • For this project, you’ll use the Web Server Gateway Interface (WSGI) package Gunicorn between the app and Kinsta’s Nginx web servers.

Most examples remove it for brevity, but you should always be mindful of how you’re accessing untrusted data. To defend against injection attacks, it’s essential to enclose all user-provided values when rendering output in HTML (the default response type in Flask). Although implementing the same function for multiple routes isn’t a big problem until you get to a certain number of routes.

What is Flask Python Used For?

It quickly becomes a frantic process when we are dealing with hundreds of routes. As we can understand from the name that static routes are fixed routes i.e. for each route functionalities we have to explicitly define the same function for each URL route. The microframework Flask is part of the Pallets Projects (formerly Pocoo), and based on several others of them, all under a BSD license. FastAPI is growing at high speed, with 48k stars on Github, 370 contributors, and more than 3.9k forks. This elegant framework built for high-performance and fast-to-code APIs is not one to miss. An interesting case is that if the defined route had a trailing slash and the client asked for the route without the slash, you wouldn’t need to double up on decorators.

This modular structure ensures greater flexibility and prevents unnecessary complexity in projects. At its core, Flask facilitates the creation of web applications through a simple yet robust foundation. It includes a built-in development server, making testing and debugging convenient during the development phase. Flask’s URL routing system maps URLs to specific view functions, promoting a structured and organized codebase.

Template Variables

It allows developers to build web applications quickly and with minimal setup. Unlike larger frameworks, Flask provides the essentials to get started, making it a popular choice for both beginners and experienced developers. Flask is often preferred over Django when developers seek a more lightweight and flexible framework. Flask’s micro framework approach allows developers to build applications from the ground up, adding components as required. This level of customization is ideal for small to medium-sized projects where a lean codebase and minimal overhead are priorities.

  • Flask’s key features cater to developers seeking simplicity, flexibility, and efficiency in their web development endeavors.
  • If you change databases or don’t want your database URL visible in source control, you’ll have to take extra steps to ensure your information is appropriate for the environment.
  • Though, as mentioned, we will use marshmallow to serialize and deserialize entities through our endpoints.

This is particularly beneficial for newcomers to web development who want to grasp the fundamentals without overwhelming complexity. Flask boasts an extensive ecosystem of extensions that enhance its capabilities. These extensions cover various functionalities such as database integration, authentication, form handling, and more. Leveraging these extensions saves development time and ensures consistent, well-tested solutions.