You set up your project and wrote a view to use for testing. Then, you used built-in tags and filters as well as loaded tags from a library. In the previous section, you learned how to register tags and filters. In this section, you’re all set to write your first Django custom filter! Filters as Functions As mentioned previously, filters are Python functions. The most basic filters take a single argument: the value to filter. The result of a filter […]

Python’s not operator allows you to invert the truth value of Boolean expressions and objects. You can use this operator in Boolean contexts, such as if statements and while loops. It also works in non-Boolean contexts, which allows you to invert the truth value of your variables. Using the not operator effectively will help you write accurate negative Boolean expressions to control the flow of execution in your programs. In this tutorial, you’ll learn: How Python’s not operator works How […]

Django is a powerful framework for creating web applications in Python. Its features include database models, routing URLs, authentication, user management, administrative tools, and a template language. You can compose reusable HTML that changes based on the data you pass to the template language. Django templates use tags and filters to define a mini-language that’s similar to Python—but isn’t Python. You’ll get to know Django templates through the tags and filters you use to compose reusable HTML. In this tutorial, […]

In many situations, you’ll need to find the number of items stored in a data structure. Python’s built-in function len() is the tool that will help you with this task. There are some cases in which the use of len() is straightforward. However, there are other times when you’ll need to understand how this function works in more detail and how to apply it to different data types. In this tutorial, you’ll learn how to: Find the length of built-in […]

If you’ve ever tried to parse an XML document in Python before, then you know how surprisingly difficult such a task can be. On the one hand, the Zen of Python promises only one obvious way to achieve your goal. At the same time, the standard library follows the batteries included motto by letting you choose from not one but several XML parsers. Luckily, the Python community solved this surplus problem by creating even more XML parsing libraries. Jokes aside, […]

If you’re using Python in the world of data science or scientific computing, you will soon discover that Python has two different packaging systems: pip and Conda. Which raises some questions: How are they different? What are the tradeoffs between the two? Which should you use? While it’s not possible to answer this question for every situation, in this article you will learn the basic differences, constrained to: Python only; Conda has support for other languages but I won’t go […]

With Python’s property(), you can create managed attributes in your classes. You can use managed attributes, also known as properties, when you need to modify their internal implementation without changing the public API of the class. Providing stable APIs can help you avoid breaking your users’ code when they rely on your classes and objects. Properties are arguably the most popular way to create managed attributes quickly and in the purest Pythonic style. In this tutorial, you’ll learn how to: […]