Django community: RSS
This page, updated regularly, aggregates Community blog posts from the Django community.
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Generating a Static Site with Flask and Deploying it to Netlify
This tutorial shows how to leverage the JAMstack with Python and Flask by creating a static site and deploying it to Netlify -
How to Limit Test Time in Django’s Test Framework
I recently optimized a client project’s test suite, and in the process found a test whose runtime had crept up ever since it had been written. The problematic test exercised an import process from a fixed past date until the current day. The test’s runtime therefore grew every day, until it reached over a minute. The solution for that test was to add a date mock using time-machine, so the test created a fixed amount of data. But we also wanted to prevent such a problem occurring again. We came up with the idea of implementing a test time limit that would automatically fail any long running tests. This way, if any appeared again, they would be detected early. The project uses Django’s test framework, which is based on unittest. Based on my spelunking of the unittest’s internals, I figured the best place to add such a limit would be in the TestCase class. The project already had its own customized subclasses of Django’s TestCase classes, so I could add the logic there. Cutting out other details, here is the implementation I came up with: import time from django import test class SlowTestException(Exception): pass class ProjectTestCaseMixin: def _callTestMethod(self, method): start … -
Which Django Version Should I Use?
Django is a big and popular web framework for Python to help you build a web app. Which Django version should you use? If you’re starting a Django web app, use the latest version of Django available. Why listen to me? I’m a software developer with over 7 years of professional Django experience. I work at companies that use Django successfully at the core of their business. I’ll explain why you should use the latest. -
Django News - Django 3.2.1 alpha 1 released - Jan 22nd 2021
News Django 3.2 alpha 1 released Django 3.2 alpha 1 is now available. It represents the first stage in the 3.2 release cycle and is an opportunity for you to try out the changes coming in Django 3.2. djangoproject.com PyCon 2021 Call for Proposals The PyCon 2021 call for proposals is open and closes on February 12, 2021. PyCon US is a massive conference--even virtually--and in recent years the web track, specifically Django, has been underrepresented vs data science/AI/ML talks. Consider applying! pycon.org Articles 5 JavaScript things you should know/understand as a Python Developer by Žan Anderle A number of good tips on better understanding modern JavaScript if you're a Python developer. zanderle.com Testing Python Applications with Pytest [Guide] A look at the most common Pytest configurations and usage, including several Pytest plugins and external libraries. stribny.name It’s time to switch to Docker BuildKit BuildKit is a stable way to dramatically improve your Docker performance when building images. pythonspeed.com Everything you need to know about Python data classes by Josue Balandrano Coronel A very in-depth look at dataclasses, their pros/cons, and multiple use cases with plenty of code examples. rmcomplexity.com 7 concepts you should know to get a job as … -
Reading CloudFlare headers in a Django middleware
For my new Django project, DB Buddy, I’m using CloudFlare as my CDN. It has a bunch of useful features that would otherwise take extra work, such as DDoS protection, HTML minification, and analytics. Since CDN’s proxy your site, all requests are seen to be coming from their servers’ IP’s, rather than actual users’ IP’s. But sometimes you need to inspect real user IP’s, for example to implement rate limiting. To help with this, CloudFlare adds several useful headers, including CF-Connecting-IP with the client’s real IP. In order to provide an interface to get the client’s IP, whether my project is running in development or production, I added a middleware to attach the client IP as request.ip: class CloudflareMiddleware: def __init__(self, get_response): self.get_response = get_response def __call__(self, request): try: ip = request.headers["CF-Connecting-IP"] except KeyError: ip = request.META["REMOTE_ADDR"] request.ip = ip return self.get_response(request) Although the middleware is short, I still made sure to write some tests. I based these on my subclass of Django’s SimpleTestCase, since no DB queries should be made. To generate example requests, I used Django’s RequestFactory. The end result was this test case with one test for each branch in the middleware: from django.http import HttpResponse from … -
Setting up a headless Raspberry Pi
Notes to my future self on setting up a headless Raspberry Pi. -
Mercurial mirror for Django 3.1 branch
As usual when Django releases a new Alpha version, I’ve settled a new mirror. The URL (both web and clone) is https://hg.freehackers.org/mirrors/django-3.2-production As stated before, I no longer use bitbucket as they’ve dropped support for mercurial. Shame on them ! 🙂 -
Simple In-Memory Caching of Django Model Data With cachetools
A client project recently was suffering from an N+1 queries problem in a complicated Django admin page. Many measures had already been taken to prevent N+1 queries, such as use of django-auto-prefetch and some manually tuned select_related() / prefetch_related() calls. The remaining N+1 in question was a bit resistant to those methods because it came through several layers of admin code and many-to-many fields, making it harder than normal to find the place to modify the QuerySet construction. Instead of spelunking through those layers of code to fix this N+1, I took a “shortcut” with some local in-memory caching. This was possible because of the particular model. The model in question represents a county in the United States: class County(auto_prefetch.Model): state = auto_prefetch.ForeignKey(State, on_delete=models.CASCADE) name = models.CharField(max_length=30) ... def __str__(self): return f"{self.name}-{self.state.abbreviation}" The N queries came from the __str__() method, which is used to display a given County in the admin. A list of N counties was selected from a related model without using select_related() or prefetch_related() to select the related states at the same time. Therefore Django performed an extra query to select the state when calling __str__() on each county. The page in question displayed a list of … -
Customer Requests - Building SaaS #88
In this episode, I worked on some customer requests now that I’ve finished launching the product. These requests improved the usability of the application in a few spots that were lacking. The first request from the customer was to make it clear on the daily view when tasks are graded or not. Before I could change the template, I need to add a new method to the CourseTask to check if the task is graded. -
Django Girls - Rachell Calhoun
RachellCalhoun.comDjangoGirls.orgGitHub profileToptal scholarship winnerDjango Girls new leadershipDjangoCon US 2016: Git in Control, Version Control and How it Could... by Rachell CalhounSupport the ShowThis podcast is a labor of love and does not have any ads or sponsors. To support the show, consider purchasing or recommending a book from LearnDjango.com or signing up for the free weekly Django News newsletter. -
Efficient Reloading in Django’s Runserver With Watchman
If you start the development server on a Django project, it looks something like this: $ python manage.py runserver Watching for file changes with StatReloader Performing system checks... System check identified no issues (1 silenced). January 20, 2021 - 04:25:31 Django version 3.1.5, using settings 'db_buddy.settings' Starting development server at http://127.0.0.1:8000/ Quit the server with CONTROL-C. When you make changes to a Python file, the server automatically reloads. This is powered by a file watcher, and Django reports which one it’s using in the first line, defaulting to StatReloader. The StatReloader class is simple but reliable. It works by running a loop that checks all your files for changes every second - this is pretty inefficient, especially as your project grows! A lesser-known but better alternative is to use Django’s support for watchman. Support was added in Django 2.2, thanks to Tom Forbes in Ticket #27685. Watchman is an efficient file watcher open sourced by Facebook. It works by receiving file change notifications from your operating system and bundling them together. When nothing is changing, it doesn’t need to do any work - saving processing power and consequently laptop battery life. And when something changes, Django gets notified about it … -
Efficient Reloading in Django’s Runserver With Watchman
If you start the development server on a Django project, it looks something like this: $ python manage.py runserver Watching for file changes with StatReloader Performing system checks... System check identified no issues (1 silenced). January 20, 2021 - 04:25:31 Django version 3.1.5, using settings 'db_buddy.settings' Starting development server at http://127.0.0.1:8000/ Quit the server with CONTROL-C. When you make changes to a Python file, the server automatically reloads. This is powered by a file watcher, and Django reports which one it’s using in the first line, defaulting to StatReloader. The StatReloader class is simple but reliable. It works by running a loop that checks all your files for changes every second - this is pretty inefficient, especially as your project grows! A lesser-known but better alternative is to use Django’s support for watchman. Support was added in Django 2.2, thanks to Tom Forbes in Ticket #27685. Watchman is an efficient file watcher open sourced by Facebook. It works by receiving file change notifications from your operating system and bundling them together. When nothing is changing, it doesn’t need to do any work - saving processing power and consequently laptop battery life. And when something changes, Django gets notified about it … -
Scheduling Celery Tasks in the (far) future
We used to make use of the fact that a celery task can be scheduled at some time in the future to auto-punch-out staff members who failed to punch out 24 hours after their shift started. This was as simple as scheduling a task with an `eta=86400`. However, as Adam points out [here](https://adamj.eu/tech/2020/02/03/common-celery-issues-on-django-projects/) (see number 5). This is not a great idea. For one, it will bog down your celery workers (and make them use a bunch more memory). Secondly, something Adam doesn't mention is that if your queue is corrupted, then all of those future tasks will not be executed. Discussing this in IRC today, I thought of a simple mechanism for scheduling these tasks and processing them at some point after they are due. We will start with a model to store our task: {% highlight python %} class ScheduledTask(models.Model): task_name = models.TextField() task_args = models.JSONField(default=list) task_kwargs = models.JSONField(default=dict) due_date = models.DateTimeField() objects = ScheduledTaskQuerySet.as_manager() @property def task(self): module, task = task_name.rsplit('.', 1) return getattr(importlib.import_module(module), task) def execute(self): self.task.apply_async(args=self.args, kwargs=self.kwargs) {% endhighlight %} We have a custom queryset defined, that allows us to see which tasks are due using a nice queryset method: {% highlight python %} class … -
Scheduling Celery Tasks in the (far) future
We used to make use of the fact that a celery task can be scheduled at some time in the future to auto-punch-out staff members who failed to punch out 24 hours after their shift started. This was as simple as scheduling a task with an `eta=86400`. However, as Adam points out [here](https://adamj.eu/tech/2020/02/03/common-celery-issues-on-django-projects/) (see number 5). This is not a great idea. For one, it will bog down your celery workers (and make them use a bunch more memory). Secondly, something Adam doesn't mention is that if your queue is corrupted, then all of those future tasks will not be executed. Discussing this in IRC today, I thought of a simple mechanism for scheduling these tasks and processing them at some point after they are due. We will start with a model to store our task: {% highlight python %} class ScheduledTask(models.Model): task_name = models.TextField() task_args = models.JSONField(default=list) task_kwargs = models.JSONField(default=dict) due_date = models.DateTimeField() objects = ScheduledTaskQuerySet.as_manager() @property def task(self): module, task = task_name.rsplit('.', 1) return getattr(importlib.import_module(module), task) def execute(self): self.task.apply_async(args=self.args, kwargs=self.kwargs) {% endhighlight %} We have a custom queryset defined, that allows us to see which tasks are due using a nice queryset method: {% highlight python %} class … -
[Django]Composite Primary Key
０．Do Django models support composite primary key? https://docs.djangoproject.com/en/3.1/faq/models/#do-django-models-support-multiple-column-primary-keys https://code.djangoproject.com/wiki/MultipleColumnPrimaryKeys Django doesn’t officially support composite primary key. If there is no field for which “primary_key = True” is specified, “id” will be automatically added as the primary key. So if you are using the DB of the conventional system, “update” and “delete” method do not work. You have to add “id” field to your tables or to make your own SQL query. １．Solutions Proposal１：Add a surrogate key If I add a surrogate key (‘id’) to the DB and put a unique constraint (unique_together) on the composite key, I can use the Django model as it is. (Problems) DB rebuild takes time and requires planned outage. Proposal２：Implement with your own query Make my own query-write implementation without relying on ORM. I can control the performance of queries by yourself. (Problems) More code and testing. Proposal３：Extend Django Model It seems that it was also considered in the Django project, but I’m not sure recent status. https://code.djangoproject.com/ticket/373 https://code.djangoproject.com/wiki/MultipleColumnPrimaryKeys#CurrentStatus It seems that some people have tried various ways, but in the end, are they all unfinished? For the time being, by extending the model myself, create a subclass of Model so that I can use … -
Adding Social Authentication to Django
This tutorial details how to set up social auth with Django and Django Allauth. -
How to gather consensus before a big decision
The next time you have an important proposal to make, don’t wait until the big meeting to ask for support. Here’s how to gather feedback and build consensus beforehand, so you can make that big meeting into a non-event. -
How to implement Auto Expiring Token in Django Rest Framework
Describes how to implement custom token model and authentication backend in Django Rest Framework -
How to implement Auto Expiring Token in Django Rest Framework
Describes how to implement custom token model and authentication backend in Django Rest Framework -
Django News - CSS, PostgreSQL, Django Security with CI/CD, and more htmx resources - Jan 15th 2021
News The State of CSS 2020: Trend Report CSS is rapidly changing with utility-first frameworks like Tailwind CSS gaining rapid prominence. This is a fun, interactive look at a recent survey on current and future CSS trends. stateofcss.com Articles Bringing Security along on the CI/CD journey From Jacob Kaplan-Moss, a detailed look at how to integrate security with modern CI/CD practices. jacobian.org Re-Introducing Hash Indexes in PostgreSQL by Haki Benita A very in-depth look at hash indexes within PostgreSQL and why they are more relevant than ever these days. hakibenita.com Detecting N+1 queries in Django with unit testing A clever way to unit test for N+1 queries in your code. valentinog.com Interview with Andrew Godwin about deployment — Django deployment From 2017 but still very relevant, an interview with on Django deployments with Andrew Godwin. djangodeployment.com Django migrations without downtimes Originally from 2015 but updated a few times since then, this is a classic look at managing Django migrations on a large site without downtimes. github.io How to Override the gunicorn Server Header by Adam Johnson Adam Johnson shows how to override Gunicorn's header which, by default, reports the complete version of Gunicorn being used: a security no-no. adamj.eu Sponsored … -
Hangar's Dumb Security Questionnaire
Over on the Hangar tech blog, I’ve posted our Dumb Security Questionnaire (the questions we ask vendors to evaluate their security maturity). All DSQs are dumb, but I think ours is a little less dumb. If not, at least it’s short. -
Squashing Bugs - Building SaaS #87
In this episode, I fixed some critical issues that my customer discovered. My customer is putting the app through its real paces for a school year and since this is the first run, there were bound to be some bugs. We began with an explanation of the issues that my customer encountered. The problems related to scheduling. First, the daily page skipped a task and showed the task that was meant for two days in the future. -
Why I'm excited to get a COVID vaccine
I’m terrifically excited to get a COVID vaccine. Not just “willing”, but actually quite excited. mRNA vaccines are this generation’s moonshot – a huge leap forward in science. Im terrifically excited to get to be part of it. -
How to accept Paypal payments on your Django application
If you are developing a Django application and you want to accept Paypal payments, you are in the right place! In this tutorial you’ll learn how to integrate Django and Paypal to accept payments in your Django web application. Paypal is a popular solution for online payments. Even if nowadays there are many valid alternatives, Paypal is still a big player in the market with a solid reputation and it’s trusted by millions of users. Here is a simple step-by-step guide on how to integrate the django-paypal third party app on your website. 1. Install the django-paypal app pip install django-paypal 2. Insert the app in your Django settings INSTALLED_APPS = ( ... 'paypal.standard.ipn', ) 3. Insert a Paypal form on a view Assuming you are using Django class-based views, you can use a FormView like this: from django.views.generic import FormView from django.urls import reverse from paypal.standard.forms import PayPalPaymentsForm class PaypalFormView(FormView): template_name = 'paypal_form.html' form_class = PaypalForm def get_initial(self): return { "business": 'your-paypal-business-address@example.com', "amount": 20, "currency_code": "EUR", "item_name": 'Example item, "invoice": 1234, "notify_url": self.request.build_absolute_uri(reverse('paypal-ipn')), "return_url": self.request.build_absolute_uri(reverse('paypal-return')), "cancel_return": self.request.build_absolute_uri(reverse('paypal-cancel')), "lc": 'EN', "no_shipping": '1', } This is a regular FormView and the template paypal_form.html is a standard Django template like this: … -
How to accept Paypal payments on your Django application
In this tutorial you’ll learn how to integrate Django and Paypal to accept payments in your Django web application. Paypal is a popular solution for online payments. Even if nowadays there are many valid alternatives, Paypal is still a big player in the market with a solid reputation and it’s trusted by millions of users. Here is a simple step-by-step guide on how to integrate the django-paypal third party app on your website. Table of Contents 1. Install the django-paypal app 2. Insert the app in your Django settings 3. Insert a Paypal form on a view 4. Provide an URL for Paypal IPN 5. Create views for success and failure of Paypal checkout 6. Setup a listener to detect successful Paypal payments 1. Install the django-paypal app pip install django-paypal 2. Insert the app in your Django settings INSTALLED_APPS = ( ... 'paypal.standard.ipn', ) 3. Insert a Paypal form on a view Assuming you are using Django class-based views, you can use a FormView like this: from django.views.generic import FormView from django.urls import reverse from paypal.standard.forms import PayPalPaymentsForm class PaypalFormView(FormView): template_name = 'paypal_form.html' form_class = PayPalPaymentsForm def get_initial(self): return { "business": 'your-paypal-business-address@example.com', "amount": 20, "currency_code": "EUR", "item_name": 'Example item, …
