See the source code for a working example. UI testing is a critical part of any modern web application. My favorite testing framework is Cypress which enables you to write clean, fast and reliable tests. It consists of two main commands: cypress run: Runs Cypress tests from the CLI without a GUI. Used mostly in CI/CD. cypress open: Opens Cypress in an interactive GUI. Used for local development. I like to dockerize my entire application so it can be run anywhere (my machine, coworker’s machine, CI/CD, etc.) and Cypress is no exception. We’re going to dockerize the cypress run and cypress open commands for a simple Todo application written in Django and Next.js (check out the source code). ...

You can use watchman in your Django project to make auto-reloads more CPU efficient. Adam Johnson’s Efficient Reloading in Django’s Runserver With Watchman blog post does an excellent job describing how to set this up. I highly recommend giving it a read. The tutorial explains how to install watchman on macOS with brew install watchman but does not explain how to install it in a Python docker container. Considering all of my Django projects are dockerized, I decided to figure it out. ...

In Django, you can define a set of choices for any field. If you’re using a SPA frontend, such as React or Vue, then you’ll need to access these choices in a form. Let’s look at two ways to do this. As an example, we’ll use the following Device model: class Device(models.Model): class Size(models.TextChoices): SMALL = "S" MEDIUM = "M" LARGE = "L" name = models.CharField(max_length=255) size = models.CharField(max_length=255, choices=Size.choices) Hardcode choices in frontend The fastest approach is to harcode these choices in the frontend. ...

In Django, a related object is a model instance used in the one-to-many or many-to-many context. For example, let’s look at the built-in User model, which has a many-to-many relationship with the Group model. class User(models.Model): groups = models.ManyToManyField(Group, related_name="groups") For any given User object, all linked Group objects are called “related objects”. Here are 5 ways to fetch all User objects with at least one related Group object. Iterate over each object in Python users = [] for user in User.objects.prefetch_related("groups"): if user.groups.exists(): users.append(user) Probably the most popular approach but there are two problems: ...

The Django ORM is a powerful tool but certain aspects of it are counterintuitive, such as the SQL order of execution. Let’s look at an example of this trap and how we can fix it using subqueries: class Book(models.Model): class Meta: constraints = [ models.UniqueConstraint( fields=["name", "edition"], name="%(app_label)s_%(class)s_unique_name_edition", ) ] name = models.CharField(max_length=255) edition = models.CharField(max_length=255) release_year = models.PositiveIntegerField(null=True) I want to write a query that reads: ...