Django community: Community blog posts RSS
This page, updated regularly, aggregates Community blog posts from the Django community.
-
Mirroring my article on Chennai 36 – The Alumni Blog of IITM
Recently, I wrote an article to Chennai36 which is a blog maintained by the Alumni Association of IITM. The article was about my opinions on how to apply to graduate school for an undergrad at IITM. In this post, I am mirroring that article on this blog. The original article can be found here. ——————————————————————————————————————————————————— The Grad Guru : Karthik Abinav at University of Maryland, College Park Note : Whenever I mean grad school, I am going to be referring to a PhD program. Though most of this advice also applies to MS programs, you should bear in mind that my focus is on PhD program. Since, I do not have much knowledge about the MS programs, I will not comment much about them in this article. 1. Please tell us about yourself, the university you are studying at, the research field you are working on, and the scope it has to offer after an MS or PhD. Also tell us about a typical day in the life of a postgraduate student. I recently started my PhD in Computer Science at University of Maryland at College Park. I am broadly interested in theoretical computer science. At a high level, ... -
Installation of PhoneGap on Debian system
I have recently been developing an application for IOS using phonegap. I was extremely fascinated by the simplicity of its usage. In this post, I will guide through a step-by-step procedure to setup phone gap on a Debian system. Setting Up PhoneGap application on a local system You will come across the term Cordova often when one talks about PhoneGap. Please note that for most purposes, both are essentially interchangeable. Here, I will give instructions to setup cordova on a Linux Debian system. You can make appropriate modifications for your operating system. The first step is to install the latest version of cordova on your system. The installation using the Command-Line Interface is extremely straight forward. 1) Install NodeJS on your system from their website. 2) Run the following to install cordova sudo npm install -g cordova 3) Once cordova is installed, now create a new project. To do that run the following command sudo cordova create photoFilter com.photoFilter.filter photoFilter Note: I am calling my example application as photoFilter. This will create folder called photoFilter in the current directory. The important files to note here are the config.xml file and the www folder. The config.xml file is where you will ... -
Mercurial Mirror For Django 1.8 Branch
Another year, another alpha release for Django and … another “production” mirror for me and anybody else interested. Django has just released the first alpha for Django-1.8. As usual, I create the mirror as soon as the corresponding branch is opened (stable/1.8.x), but this is still alpha stuff for you to test, not anything stable you […] -
Importing your old comments to Disqus site
In one of my latest blogpost on disqus I covered topics on integrating Disqus to the website and disqus SSO. In this post, I will let you know how to migrate the older comments to Disqus. If you sneak peek in to the alluring features of disqus you may make your mind to migrate your custom commenting system on your blog to use disqus commenting system. The threaded comments and replies, powerful moderation and admin tools, RSS options and many more features come in as battaries included with Disqus which makes the commenting more interactive and easy to deal with. Let us kick start the process. Till date importing the old comments directly from the blogger and wordpress to disqus is feasible. This can be achieved by using tools and plugins that are already existing in them and its pretty straight forward. In this post our prime concern will be laid on custom XML import format. If you are using neither blogger, nor wordpress the custom XML import format which is based on the WXR (WordPress eXtended RSS) schema comes to the rescue. Disqus also supports MovableType, and IntenseDebate but preferably WXR is of more concern. I consider a case ... -
SSL broken in gevent on Python 2.7.9 – a debugging tale of woe
I thought it would be worth writing this up quickly as a blog post, just so it’s documented, though I’m guessing the bug is common knowledge by now. The process of finding out the issue was (eventually) enlightening for me though, especially how far the initial problem was from the bug. I was having problems last week deploying changes to one of our projects hosted on Heroku. I’d done a full run-down of dependencies trying to bring in security and bug fixes, making everything python 2.7 and Trusty compatible (or, for Heroku, cedar-14 stack compatible). Everything worked fine locally, even using foreman (which is the heroku tool that runs your code as if it was deployed on Heroku – in this case running through gunicorn with gevent). However, on deploying to a clean app and database on Heroku, the Persona Single-Sign-On authentication wasn’t working. The project’s settings are slightly involved, but the fact the admin site was working and the fact I was getting a login at all indicated that things were probably okay on the Django side of things. Persona itself worked fine locally, and on stage and production deployments on Heroku. I suspected DNS issues, but this turned ... -
Updated instructions to fix macbook pro with black screen
Last week I wrote about my macbook pro and its screen that suddenly stayed black after waking it from sleep. Including instructions on how to fix it. I now have improved instructions... The piece of crap did it again. (This time there was no external monitor in play, btw) Symptoms: you open up your late 2014 macbook pro 15" and expect it to wake from sleep in 0.5 seconds. Instead the screen stays black. Press shift-option-control-power and release them all at the same time. This resets the "system management controller", amongst others it makes sure the "power" button actually reacts. Now look at the back of your mac's screen. Make sure the light of the apple logo is off. If necessary, keep the power button pressed for 5 seconds to force a shutdown. (The power button should work again after step 1). Keep your fingers ready for pressing command-option-p-r at the same time. You need both hands for this weird combination. Press the power button and then hold these four keys. Your mac will now actually boot, give you the startup sound and lo and behold, you've got your screen back. I do hope apple will fix this Real Soon. ... -
Actually doing work - proof by blogging
I'm a programmer. Which means it is not always clear when I'm working. What I mean is that, if I'm sitting behind my screen, I might be reading an article about postgres performance improvements, but I might also be reading the news. And clicking on my ipad might mean I'm keeping my python knowledge up to date by reading weblogs, but I might also be reading some comics. Typing furiously on my keyboard might indicate great productivity, but it also might indicate a long personal email. The other way around, sitting nicely in the living room at home, clicking away on the laptop, might mean I'm relaxing by writing an update on my model railway work on a forum, but it might also mean I'm finishing off a work project in my own time. "Doing research" is a potential problem for me. I've spend a ton of time reading about Ansible and on how to use it. But it was only when I actually started doing something with it that I started to wrap my head around it. So... just reading and thinking is dangerous to my productivity. I want to be productive. One of the simplest tricks I can ... -
New emacs setup
I edit all my code with emacs. Since 1996 or so. And all blog entries. And all... So my emacs settings are "quite important" to me. When I installed the new laptop I'm typing this on, my settings stopped working: I just deleted my ~/.emacs.d/ directory because I wanted to upgrade my setup. Since a couple of years I used the emacs starter kit version 2. The link goes to my slightly modified copy of the original version 2 starter kit. The setup change I wanted to make was to update to the version 3 of the emacs starter kit. That link goes to the real starter kit, which in version 3 is... just a text document! Which is a good thing. You don't need to clone a git repo just to get a bunch of settings. You use emacs' package tool to download the better-defaults package, which contains most/all of the settings changes that made the original emacs starter git such a joy to use. And on top of that, it suggests a couple of handy packages to use also. I'm using all of the suggested ones (apart from 'scpaste', which I don't use). And it provides a template ... -
VariableDoesNotExist: Failed lookup for key [text] in 'None'
VariableDoesNotExist: Failed lookup for key [text] in 'None', that was the error that I got out of an internal django app that I wrote. The app is the most error-free one that I ever build, so I was quite surprised. I was even more surprised when I started debugging it. The error was in the search functionality. Searching for "lizard" would give an "error 500" page. Searching for "lizar" gave 0 results (which is fine), for "lizardd", too. "lidard" also gave 0 results. Only a search for "lizard" crashed the site. Huh? Weird. I got the question whether I put a hidden message into this app (as "lizard" is one of our main products) :-) Locally it all worked fine, of course. Only on the server did I see the error. Here's the relevant part of the traceback: Stacktrace (most recent call last): File "django/core/handlers/base.py", line 112, in get_response response = wrapped_callback(request, *callback_args, **callback_kwargs) File "haystack/views.py", line 50, in __call__ return self.create_response() File "haystack/views.py", line 144, in create_response return render_to_response(self.template, context, context_instance=self.context_class(self.request)) File "django/shortcuts/__init__.py", line 29, in render_to_response return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs) File "django/template/loader.py", line 169, in render_to_string return t.render(context_instance) File "django/template/base.py", line 140, in render return self._render(context) ... File ... -
Proxying objects in Python
A lazy object proxy is an object that wraps a callable but defers the call until the object is actually required, and caches the result of said call. These kinds of objects are useful in resolving various dependency issues, few examples: Objects that need to held circular references at each other, but at different stages. To instantiate object Foo you need an instance of Bar. Instance of Bar needs an instance of Foo in some of it methods (but not at construction). Circular imports sound familiar? Performance sensitive code. You don't know ahead of time what you're going to use but you don't want to pay for allocating all the resources at the start as you usually need just few of them. There are other examples, I've just made up a couple for context. If you've used Django you may be familiar with SimpleLazyObject. For simple use-cases it's fine, and if you're already using Django the choice is obvious. Unfortunately it's missing many magic methods, most glaring omissions: __iter__, __getslice__, __call__ etc. It's not too bad, you can just subclass and add them yourself. But what if you need to have __getattr__? The horrors of the infinite recursive call beckon. ... -
Macbook pro black screen and restart problem
This morning I took my macbook pro (a very nice late 2014 retina 15" one) out of my backpack, opened it and plugged in the external monitor. But it stayed black. The macbook's own screen also stayed black. Ouch? It didn't seem to wake up... Some standard things I checked/tried: The battery couldn't be empty yet. The apple logo on the back of the screen was illuminated, right? Of course I had already attached it to the power cord. Which showed its LED, so power wasn't the problem. Screen brightness. Perhaps I dialed it down to zero by accident? No. Close/open again. Take out external display. Etc. Nope. Ok, time to press the power button. No reaction that I could see/hear. Press it 10 seconds. No. Problem with such a new macbook is that it doesn't have a harddisk. The noises a harddisk makes tend to provide pretty good feedback on what's happening normally :-) I just couldn't get the macbook to reset (or shut down)! If the power button doesn't work... Googling turned up two additional tricks: Resetting the "SMC", the system management controller. One of the things it does is monitor the power button... Press shift-option-control-power and release ... -
How to automatically tag and categorize photos according to their content
Drawing insights from user generated content can be very useful. If you allow users to upload images, you might want to better understand what their images contain. Whether a photo is of a landscape, people, animals, or nightlife, image processing and analysis can assist in further comprehension. ReKognition scene categorization Cloudinary takes care of the entire image management pipeline, from uploading, via dynamic image manipulation, to fast CDN delivery. You can use Cloudinary with our add-on for automatic scene categorization provided by ReKognition, a visual recognition solution developed by Orbe.us. The ReKognition scene categorization add-on analyzes scenes within photos and allows you to automatically classify your website’s images into a long list of potential categories. Improve user experience, engagement and conversion By automatically recognizing what images contain, developers can easily create pages or site sections based on images’ content (e.g. photos of animals, travel, special events, etc.). In addition, if your site supports a search option, you can have the search results include relevant images based on their visual content instead of just by their file names or user-assigned tags. These benefits can improve user experience on your site and increase engagement. When you identify image content, you then know ... -
Integrating front-end tools with your Django project
Front-end tools like Grunt and Gulp are becoming very widespread, and there’s good reason for it. The front-end code is no longer static, CSS pre-processors are the norm, and JavaScript modules such as Require, Browserify or even coffeescript are also becoming more common as well. On top of that, when you’re deploying to production, you want to minify everything but when you’re in development mode, you want sourcemaps for JS and CSS among other things. At Lincoln Loop, we use Gulp as our task runner to do the following things: Compile Sass into CSS, including autoprefixer support Compile JavaScript with Browserify Add sourcemaps for our compiled JavaScript and CSS Minify images with imagemin Reload the browser automatically on JavaScript (and/or template) changes Refresh the CSS without reloading the browser on CSS changes Trigger system notifications when Sass or JavaScript has errors Minify JavaScript and CSS for production deploy and finally: Generate a build folder where all the generated files are stored We won’t go into details about our Gulp setup on this post, there’s plenty of information out there (we wrote about Grunt before). If you’re curious about the code thou, here’s a gist of a gulpfile-in-one that includes most ... -
Example Ember.js + Django + Django Rest Framework single-page application
Ember.js is one of JavaScript frameworks for creating interactive single page web applications. Pages may change but the browser doesn't reload the page. This framework has some similarities with Django and can be good pick to start with such frontend applications for Django developers with some JavaScript knowledge. In this article I'll show you an example Django + Django Rest Framework + Ember.js application. Classical posts and categories done in Ember and in Django for comparison. -
Almost premature optimization
In airmozilla the tests almost all derive from one base class whose tearDown deletes the automatically generated settings.MEDIA_ROOT directory and everything in it. Then there's some code that makes sure a certain thing from the fixtures has a picture uploaded to it. That means it has do that shutil.rmtree(directory) and that shutil.copy(src, dst) on almost every single test. Some might also not need or depend on it but it's conveninent to put it here. Anyway, I thought this is all a bit excessive and I could probably optimize that by defining a custom test runner that is first responsible for creating a clean settings.MEDIA_ROOT with the necessary file in it and secondly, when the test suite ends, it deletes the directory. But before I write that, let's measure how many gazillion milliseconds this is chewing up. Basically, the tearDown was called 361 times and the _upload_media 281 times. In total, this adds to a whopping total of 0.21 seconds! (of the total of 69.133 seconds it takes to run the whole thing). I think I'll cancel that optimization idea. Doing some light shutil operations are dirt cheap. -
Terrible choices: MySQL
I've used MySQL for a while now, and there were lots of surprising things I needed to cater for. This is from a Django and MySQL 5.5 perspective [*]. Later on you'll see the horrible things I did to work around. It was a terrible experience, as I've also used PostgreSQL ... Feel free to add your own experiences in the comments section. The defaults* MySQL supports a large part of the ANSI SQL 99 standard, however the default settings are nowhere close to that. If you used any other database then it's going to be a very perplexing experience. SQL mode* With the default settings MySQL truncates and does other unspeakable things to data for the sake of not giving errors. Where is this a correct choice, hard to say. What the defaults allow: Storing invalid dates like '0000-00-00' or '2010-01-00' [1]. Silently treating errors like: Specifying an unavailable storage engine. It will use the default engine, silently [2]. Inserting invalid data. Larger strings get truncated to the maximum length. Larger integers get truncated to the maximum. Other things get converted to NULL if the column allows that. All silently [3]. And no, ORMs won't save you from this ... -
Custom Django Admin Actions
Doing bulk data actions in the admin is easy, if you know how to do it. In this video you will learn how to create your own custom admin actions so you can update a lot of data objects all at the same time.Watch Now... -
A quick introduction to Docker containers for Django web developers
Docker is a platform for running applications in isolation. Using Linux containers makes the software layer isolated from the base system. The overhead needed for hardware virtualization used by for example Virtualbox is removed. Docker can help in development and deployment of web based applications and services - let us see how and when. -
I did an Aú Batido in 2014, now what?
This is my summary of my resolutions for 2014 and an early pass at my resolutions for 2015. I'm doing this right now instead of at the end of the year because as of the afternoon of December 21, I'm going off the grid. Resolutions Accomplished in 2014 Release the second edition of Two Scoops of Django. Visited South America. Visited two new nations, Argentina and Brazil. Went back to the East Coast to visit Philadelphia and places in New Jersey. Went back to the Philippines. Took some awesome road trips around the USA. My favorite was driving up the Pacific Coast Highway. Took a fun class with Audrey. We did woodshop! Learned how to do Aú Batido! General Accomplishments Published Two Scoops of Django 1.6 with my awesome wife, Audrey Roy Greenfeld. Experienced my first major surgery. Started working at Eventbrite. Found a Inland Empire Capoeira group but still remained friends with Capoeira Batuque. Gave talks at: Wharton School of Business Web Conference PyDay Mendoza Python Brazil PyCon Argentina Experienced the unbelievably tasty asado (steak) of Argentina. Participated in organizing the first Django Bar Camp. Played in 2 Capoeira Rodas in Brazil. Participated in the effort to reboot LA ... -
Server migration for BotBot.me
End of last week vitaly and I launched a redesign of BotBot.me user account. You can now suport us by subscribing to it for 3$/month and even log personal channel for 2$/month. If you are curious check it out here I would like to share with you the scenario & tactics we used to do this with least service interruption. BotBot.me receives less traffic than most our customers site but it collects hundreds of messages per minutes which lead to interesting challenges. As part of this deployment we were also changing cloud provider. So we needed to move all the underlying infrastructure. Here it is the main services constituing BotBot.me: redis postgresql go IRC client python plugins django web interface We use slatstack to configure our servers. I am not going to present the detailed configuration of each pieces but instead explain the strategy we followed. Reverse Proxy From now on legacy_server is the legacy server and new_server the new server. On this project we use nginx to do the TLS termination, serving static assets and finally reverse proxying the django app. We use autossh to create ssh tunnel from new_server to legacy_server. Here it is an example for redis: ... -
Quick Introduction to Mock
Quick Introduction to Mock -
Naming things: don't use reserved words
I'm currently cleaning up some code. Some people just cannot spell "p-e-p-8" if their lives depended on it, apparently. Luckily I'm civilized so I only threaten with dismemberment. Look at this gem I just uncovered: tg_after = instance.filter.technischegegevensfilter_set.exclude( pk=instance.pk).filter( datum_vanaf__gt=instance.datum_vanaf).order_by( 'datum_vanaf')[:1] Don't mind about the Dutch in there. Just look at those two filter words in the first two lines. They're even nicely underneath each other. At least they are now, I first had to fit the 159 characters long line within 78 characters, of course. In Django, you do sql filtering with .filter(some_condition=42). That's not what's happening in the first line, though. There's a foreign key called filter there! So the first filter is the name of a foreign key and the second filter is the filter method that is used everywhere in Django. Big confusion. And big chance that someone else that reads the code messes it up somehow. So... steer clear of common words used in your programming language or framework or whatever. Some examples: Don't use type as an name. Use customer_type or station_type or whatever. Only use type by itself if you really mean the python build-in. Don't use class. Either use the standard klass ... -
Introducing django-nocaptcha-recaptcha
Introducing django-nocaptcha-recaptcha -
Build a scalable Twitter clone with Django and GetStream.io
Have a look at this tutorial on how to build a scalable twitter clone using django and getstream.io Share and Enjoy: -
Building a RESTful API with Django-rest-framework
API's turned to be the heart of every application in our time. With the rise of social media, API's are being developed at a faster pace and gaining a lot of attention. Gone are the days where RPC architectures like CORBA and XML-RPC are used to enable the exchange of information and REST has taken its place making its mark in getting the things pretty straight forward. We use APIs in our everyday life. Take an instance booking a ticket for a movie through some website. Here is the process that takes place in the background. When dealing with the payment for the ticket, the website connects to the bank and sends your credit card details to the remote application and it gets verified. And once, the payment is confirmed by the remote application, it sends a confirmation response to the movie booking website to issue the tickets. The payment stuff turned possible here as the bank facilitates an API through which a website can connect to it and deal with the payments which resulted us an effective and seamless transaction. In this post we will get to know how to build a Restful API for an application using a ...
