Django community: Community blog posts RSS
This page, updated regularly, aggregates Community blog posts from the Django community.
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Django Tips & Tricks #4 - Make Django Development Server Persistent
I use Emacs for writing Python code. I also use real-auto-save to save my files after 10 seconds of inactivity.While coding, when I stop writing in the middle, after 10 seconds Emacs auto saves the file. Django recognizes this & reloads the development server.Once I complete writing code, I go to browser & refresh the page. Since the code I was writing was incomplete somewhere in the middle and had some errors, Django development server was stopped and page won't reload. Now I have to go back to terminal and restart the server and again go back to browser to refresh page.To overcome this, Django server must be made persistent. The easiest way to accomplish this is to use a simple bash script as described here.$ while true; do python manage.py runserver; sleep 4; doneWhen Django development server stops, after 4 seconds it tries to start automatically and goes on forever.Instead of typing that everytime, it better to write this as a shell script and put it in system path, so that it can be used in any project.while true; do echo "Re-starting Django runserver" python manage.py runserver sleep 4doneSave this & make it executable(chmod +x), use it is ./filename.sh … -
News and such
First things first: though I announced this sort of quietly at the time, I should probably announce it publicly as well: after four years as part of the MDN development team, as of last month I am no longer at Mozilla. There are some parallels to the last time I moved on, so I’ll link to that in lieu of writing it all over again. For the moment I’m enjoying a summer vacation, but I’m ... Read full entry -
News and such
First things first: though I announced this sort of quietly at the time, I should probably announce it publicly as well: after four years as part of the MDN development team, my final day at Mozilla was early last month. There are some parallels to the last time I moved on, so I’ll link to that in lieu of writing it all over again. For the moment I’m enjoying a summer vacation, but I’m at ... Read full entry -
Understanding Django Middlewares
I assume you have read official Django docs on middleware. I will elaborate on things mentioned in the documentation but I assume you are familiar with basics of middleware. In this post we will discuss the following. What is a middleware When to use middleware Things to remember when writing middleware Writing some middlewares to understand how order of middleware matters What is a middleware Middlewares are hooks to modify Django request or response object. Putting the definition of middleware from Django docs. Middleware is a framework of hooks into Django’s request/response processing. It’s a light, low-level “plugin” system for globally altering Django’s input or output. When to use middleware You can use middleware if you want to modify the request i.e HttpRequest object which is sent to the view. Or you might want to modify the HttpResponse object returned from the view. Both these can be achieved by using a middleware. You might want to perform an operation before the view executes. In such case you would use a middleware. Django provides some default middleware. eg: AuthenticationMiddleware Very often you would have used request.user inside the view. Django wants user attribute to be set on request before any view … -
Profiling Django Middlewares
I assume you have a basic understanding of Profiling, what it means and why we use it. Why this post Recently I had to profile a Django application which wasn't performing as fast as it should. This application had several custom middlewares too. So it was possible that custom middlewares were the cause of slow performance. There are some existing Django libraries to profile Django code. eg: Django Debug Toolbar, django-silk , django_cprofile etc. Most of them can profile view code well but they can't profile other middlewares. I wanted a way to profile middlewares too. Problem with Django Debug Toolbar I assume you understand middlewares and how the order in which middlewares are defined matter. If you want to get more idea about middlewares, this post might help. Django debug toolbar is probably designed for profiling the views. It uses process_view() and returns an HttpResponse instace from process_view(). process_request() of all middlewares run before any middleware's process_view(). So using Django debug toolbar, it's not possible to profile what's going on inside process_request() of different middlewares. And since process_view() of debug toolbar returns HttpResponse, process_view() of other middlewares is bypassed and so we can't profile process_view() of other middlewares. So … -
How to access your Django site from a different computer
Hey guys! Today we'll see how to access your Django site from another computer. Now this won't be a problem if you've hosted on a remote server like PythonAnywhere or Heroku. But what if you have hosted it on your local machine and want to provide people with access to it?I'm developing an online mentorship platform for my college that is hosted on the college server. So for that I had to use this concept. Before you do this, however, here's a disclaimer: only computers connected in the same network as your local machine can access your Django site. You can, of course, provide global access, but there's a lot of complicated networking stuff involved in that. Let's not go into that right now.So let's get on with it. You know the command for hosting and accessing the site on your local machine is python manage.py runserver. This essentially gives your local machine server capabilities and lets you access it from the same machine. However, to let other machines access it, here's the command:python manage.py runserver <ip_address>:<port_number>Replace <ip_address> with your machine's IP address. If you don't know the IP address, do one of the following:Windows: Open command prompt and type ipconfig. … -
Django Birthday: Recap
Django Birthday: Recap -
Q3 2015 ShipIt Day ReCap
Last Friday marked another ShipIt Day at Caktus, a chance for our employees to set aside client work for experimentation and personal development. It’s always a wonderful chance for our developers to test new boundaries, learn new skills and sometimes even build something entirely new in a single day. NC Nwoko and Mark Lavin teamed up to develop a pizza calculator app. The app simply and efficiently calculates how much pizza any host or catering planner needs to order to feed a large group of people. We eat a lot of pizza at Caktus. Noticing deficiencies in other calculators on the internet, NC and Mark built something simple, clean, and (above all) well researched. In the future, they hope to add size mixing capabilities and as well as a function for calculating the necessary ratios to provide for certain dietary restrictions, such as vegan, vegetarian, or gluten-free eaters. Jeff Bradberry and Scott Morningstar worked on getting Ansible functioning to replace SALT states in the Django project template and made a lot of progress. And Karen Tracey approached some recent test failures, importing solutions from the database, while Rebecca Muraya began the massive task of updating some of our client based … -
Repository for existing Extbase model class
If you want to use an existing extbase model like Category but want to create a custom repository to implement some custom queries, here is the way to go: Create typo3conf/ext/your_ext/Classes/Domain/Model/Category.php: <?php namespace Dummy\YourExt\Domain\Model; /** * Category */ class Category extends \TYPO3\CMS\Extbase\Domain\Model\Category { } Create typo3conf/ext/your_ext/Classes/Domain/Repository/CategoryRepository.php: <?php namespace Dummy\YourExt\Domain\Repository; /** * The repository for Categories */ class CategoryRepository extends \TYPO3\CMS\Extbase\Domain\Repository\CategoryRepository { // some custom query methods here } Create typo3conf/ext/your_ext/ext_typoscript_setup.txt: config.tx_extbase{ persistence{ classes{ Dummy\YourExt\Domain\Model\Category { mapping { tableName = sys_category recordType = Tx_YourExt_Category } } } } } Clear the cache and you're ready to go! -
Frontend Code Strategy with Django
Web development is getting more and more focused on front-end development. This leads to a lot of questions on what is the best way to handle compiling css, javascript, coffeescirpt, stylus, etc. Having been involved with a project where the frontend deals with 100+ files between stylus files, coffeescirpt files, javascript, and css. This is kind of crazy to manage without a good strategy or even knowing how to accomplish it. How Frontend Code Works in Django When working with django you need to consider how the code is going to go from your code base to be displayed in the browser. The normal path it takes is to live in a static directory which you edit and run locally. Then in production you do a collectstatic command and it moves everything to a folder for your webserver to pull from. With that in mind as long as the above happens you can do almost anything you want for your frontend code. Lets take a look at the 3 most common ways you can do front-end development with django. Three Popular Ways to Write Frontend Code Everything in the static folder The most common way we start projects is to … -
Rendering your STL files with matplotlib using numpy-stl
It’s been a while since the first version of numpy-stl and a lot has changed since. Most importantly, usage has become even easier. So here’s a demo on how to use matplotlib to render your stl files: from stl import mesh from mpl_toolkits import mplot3d from matplotlib import pyplot # Create a new plot figure = pyplot.figure() axes = mplot3d.Axes3D(figure) # Load the STL files and add the vectors to the plot your_mesh = mesh.Mesh.from_file('tests/stl_binary/HalfDonut.stl') axes.add_collection3d(mplot3d.art3d.Poly3DCollection(your_mesh.vectors)) # Auto scale to the mesh size scale = your_mesh.points.flatten(-1) axes.auto_scale_xyz(scale, scale, scale) # Show the plot to the screen pyplot.show() You can make the render prettier yourself of course, but it is certainly useful for testing. Link to this post! -
Einladung zur Django-UserGroup Hamburg am 08. Juli
Das nächste Treffen der Django-UserGroup Hamburg findet am Mittwoch, den 08.07.2015 um 19:30 statt. Achtung: Neue Location! Dieses Mal treffen wir uns in den Räumen der Smaato Inc., Valentinskamp 70, Emporio 19. Stock in 20355 Hamburg. Auf diesem Treffen gibt es einen Vortrag über TDD für APIs von Michael Kuehne. Bitte seid um ca. 19:20 unten im Foyer, wir fahren dann gemeinsam in den 19. Stock. Wer später kommt, sagt bitte am Empfang bescheid, dass er zur Smaato Inc möchte und wird dann hoch gelassen. Eingeladen ist wie immer jeder der Interesse hat sich mit anderen Djangonauten auszutauschen. Eine Anmeldung ist nicht erforderlich, hilft aber bei der Planung. Weitere Informationen über die UserGroup gibt es auf unserer Webseite www.dughh.de. Die Organisation der Django-UserGroup Hamburg findet ab jetzt über Meetup statt. Um automatisch über zukünftige Treffen informiert zu werden, werdet bitte Mitglied in unserer Meetup-Gruppe: http://www.meetup.com/django-hh -
Observations on the nature of time. And javascript.
In the course of working on one of our latest projects, I picked up an innocuous looking ticket that said: “Date pickers reset to empty on form submission”. “Easy”, I thought. It’s just the values being lost somewhere in form validation.And then I saw the ‘in Firefox and IE’ description. Shouldn’t be too hard, it’ll be a formatting issue or something, maybe even a placeholder, right? Yeah, no. Initial Investigations Everything was fine in Chrome, but not in Firefox. I confirmed the fault also existed in IE (and then promptly ignored IE for now). The responsible element looked like this: <input class="form-control datepicker" data-date-format="{{ js_datepicker_format }}" type="date" name="departure_date" id="departure_date" value="{{ form.departure_date.value|default:'' }}"> This looks pretty innocent. It’s a date input, how wrong can that be? Sit comfortably, there’s a rabbit hole coming up. On Date Inputs Date type inputs are a relatively new thing, they’re in the HTML5 Spec. Support for it is pretty mixed. This jumps out as being the cause of it working in Chrome, but nothing else. Onwards investigations (and flapping at colleagues) led to the fact that we use bootstrap-datepicker to provide a JS/CSS based implementation for the browsers that have no native support. We have … -
Upgrading Django Projects - Introduction
One questions I am asked quite often is how to upgrade larger projects to a newer Django release. While upgrading to a newer minor release is usually really easy and does not require much work it can become a bit harder upgrading to a new major release. My oldest project points back to 0.9x, so it has seen some upgrades, and there are certain patters that proved to work pretty well. Upgrading a Django project is not harder or easier than upgrading any other project of the same size which is using a big third party framework as base and smaller libraries for certain parts of the system. I will try to start with general and simple principles on upgrading projects and move to more Python and Django specific topics later on. Before upgrading you should ask yourself if you have to. Let us assume your application is running fine and you are on a release that still gets bugfix and security updates. You could upgrade to get new features that eventually help you down the road. Or you could implement a new feature that separates your application from all competitors. The answer in that case is pretty obvious, isn’t … -
Wrapping Up CycleMento
in this video we wrap up the Building a Product series by doing an overview of topics we discussed in the previous 11 videos.Watch Now... -
Announcing the Evennia example-game project "Ainneve"
The Evennia example-game project is underway! I was quite impressed with the response I got on the mailing list to my call for developing an Evennia example game (see my Need your Help blog post).The nature of the responses varied, many were from interested people with little to no experience in Evennia or Python whereas others had the experience but not the time to lead it. It was however clear that the interest to work on an "official" Evennia game is quite big. I'm happy to announce, however, that after only a week we now have a solid lead developer/manager, George Oliver. Helping him on the technical/architecture side is Whitenoise (who, despite a barren github profile, is a professional developer). George put together a game proposal based on the OpenAdventure rpg, an open-source (CC-SA) ruleset that is also found on github. The example game is to be named "Ainneve" and its development is found in a in a separate repository under the github Evennia organisation.All the relevant links and future discussion can be found on the mailing list.George and whitenoise have already made it clear that they aim to not only make Ainneve a good example Evennia game for others to … -
The Django template language
Basics: A template is a text document, or a normal Python string, that is marked-up using the Django template language. Template system in Python can be used in the following way: First, compile the raw template code into a Template object. Then, call the render() method of the Template object with a given context. Rendering a context: Once you have a compiled Template object, you can render a context or multiple contexts with it. We have a Context class at django.template.Context, and its constructor takes two (optional) arguments: 1. A dictionary mapping variable names to variable values. 2. The name of the current application. Example: from django.template import Template, Context # Creating a Template object by instantiating it and its constructor takes one argument i.e., raw template code. template = Template("My name is {{my_name}}") context = Context({"my_name":"XXX"}) # Calling the Template object's render() method with the context to fill the template. template.render(context) Templates: A template is simply a text file. It can generate any text-based format (HTML, XML, CSV, etc.). A template contains variables, which get replaced with values when the template is evaluated, and tags, which control the logic of the template. The following example … -
The Django template language
Basics: A template is a text document, or a normal Python string, that is marked-up using the Django template language. Template system in Python can be used in the following way: First, compile the raw template code into a Template object. Then, call the render() method of the Template object with a given context. Rendering a context: Once you have a compiled Template object, you can render a context or multiple contexts with it. We have a Context class at django.template.Context, and its constructor takes two (optional) arguments: 1. A dictionary mapping variable names to variable values. 2. The name of the current application. Example: from django.template import Template, Context # Creating a Template object by instantiating it and its constructor takes one argument i.e., raw template code. template = Template("My name is {{my_name}}") context = Context({"my_name":"XXX"}) # Calling the Template object's render() method with the context to fill the template. template.render(context) Templates: A template is simply a text file. It can generate any text-based format (HTML, XML, CSV, etc.). A template contains variables, which get replaced with values when the template is evaluated, and tags, which control the logic of the template. The following example … -
Django Inclusion Tags
Django’s template system comes with a wide variety of built-in tags and filters designed to address the presentation logic needs of your application. You can extend the template engine by defining custom tags and filters using Python, and then make them available to your templates using the {% load %} tag. Custom template tags and filters must be inside a Django app. If they relate to an existing app it makes sense to create them there; otherwise, you should create a new app to hold them. The app should contain a template tags directory, at the same level as models.py, views.py, etc. If this doesn’t already exist, create it - don’t forget to include __init__.py file to ensure the directory is treated as a Python package. Your custom tags and filters will be there in a module inside the template tags directory. The name of the module file is the name you’ll use to load the tags later, so be careful to pick a name that won’t clash with custom tags and filters in another app. For example, if your custom tags/filters are in a file called poll_extras.py, your app layout might look like this: polls/ |- … -
Inclusion Tags
Django’s template system comes with a wide variety of built-in tags and filters designed to address the presentation logic needs of your application. You can extend the template engine by defining custom tags and filters using Python, and then make them available to your templates using the {% load %} tag. Custom template tags and filters must be inside a Django app. If they relate to an existing app it makes sense to create them there; otherwise, you should create a new app to hold them. The app should contain a templatetags directory, at the same level as models.py, views.py, etc. If this doesn’t already exist, create it - don’t forget to include __init__.py file to ensure the directory is treated as a Python package. Your custom tags and filters will be there in a module inside the templatetags directory. The name of the module file is the name you’ll use to load the tags later, so be careful to pick a name that won’t clash with custom tags and filters in another app. For example, if your custom tags/filters are in a file called poll_extras.py, your app layout might look like this: polls/ |- __init__.py … -
Reading MT940 files using Python
Some time ago I wrote a library to read MT940 files with Python. While there are multiple libraries available for this target, none of the others really work properly and/or support all variants of the format. The MT940 library I wrote is slightly different, it’s designed to be able to parse any MT940 file, regardless whether it’s correct or complete. The initial version of the library was very strict and only supported files that perfectly followed the standards, a few months after the release it became obvious that most banks either used different standards when implementing the standard or interpreted the standard different. Regardless, the library gave little to no results or even crashed on some MT940 files. Upon reflection I rewrote nearly all of the code to have a script that is flexible enough to support any format (even supporting custom processors for specific format) and wrote test code that tested every MT940 file I could find on the web. The result… a library that parsers pretty much everything out there while still maintaining a reasonable amount of results. Usage? As simple as you might imagine. After installing (pip install mt-940, note the dash) usage can be as simple … -
Django Birthday Party
Django Birthday Party -
Beyond Request-Response
Examining one of Django's key abstractions and how it could be updated for a more modern age. While I love Django dearly, and I think the rate of progress we keep on the project draws a fine balance between progress and backwards-compatibility, sometimes I look ahead to the evolving Web and wonder what we can do to adapt to some more major changes. We're already well-placed to be the business-logic and data backend to more JavaScript-heavy web apps or native apps; things like Django REST Framework play especially well into that role, and for more traditional sites I still think Django's view and URL abstractions do a decent job - though the URL routing could perhaps do with a refresh sometime soon. The gaping hole though, to me, was always WebSocket support. It used to be long-poll/COMET support, but we seem to have mostly got past that period now - but even so, the problem remains the same. As a framework, Django is tied to a strict request-response cycle - a request comes in, a worker is tied up handling it until a response is sent, and you only have a small number of workers. Trying to service long-polling would … -
Buildout and Django: djangorecipe updated for gunicorn support
Most people in the Django world probably use pip to install everything. I (and the company were I work, Nelen & Schuurmans) use buildout instead. If there are any other buildout users left outside of zope/plone, I'd love to hear it :-) First the news about the new update, after that I'll add a quick note about what's good about buildout, ok? Djangorecipe 2.1.1 is out. The two main improvements: Lots of old unused functionality has been removed. Project generation, for instance. Django's own startproject is good enough right now. And you can also look at cookiecutter. Options like projectegg and wsgilog are gone as they're not needed anymore. The latest gunicorn releases didn't come with django support anymore. You used to have a bin/django run_gunicorn (or python manage.py run_gunicorn) management command, but now you just have to run bin/gunicorn yourproject.wsgi. And pass along an environment variable that points at your django settings. With the latest djangorecipe, you can add a scripts-with-settings = gunicorn option and it'll create a bin/gunicorn-with-settings script for you that sets the environment variable automatically. Handy! Advantage of buildout. To me, the advantage of buildout is threefold: Buildout is more fool-proof. With pip/virtualenv you should remember … -
Need your help
This for all you developers out there who want to make a game with Evennia but are not sure about what game to make or where to start off.We need an example gameOne of the main critiques Evennia get from newbies is the lack of an (optional) full game implementation to use as an example and base to build from. So, Evennia needs a full, BSD-licensed example game. I'm talking "diku-like", something you could in principle hook up and allow players into within minutes of installing Evennia. The Tutorial world we already have is a start but it is more of a solo quest, it's not designed to be a full multiplayer game. Whereas Evennia supports other forms of MU* too, the idea is that the systems from a more "code-heavy" MUD could easily be extracted and adopted to a more freeform-style game whereas the reverse is not generally true. The exact structure of such a game would be up to the person or team taking this on, but it should be making use of Evennia's api and come distributed as a custom game folder (the folder you get with evennia --init). We will set this up as a separate …
