Lincoln Loop

Django 1.0 Template Development Book Review

October 15, 2009 | django, review | Only one comment so far.

Packt Publishing was nice enough to send us a copy of Django 1.0 Template Development by Scott Newman for review recently. I get most of my technical information via the web, so picking up a technical book was a nice change of pace. This is a well written and enjoyable read for people looking to learn a little more about Django than what is provided in the Django tutorial.

Based on the title, I expected a thorough write-up of the template system for front-end developers. With the way Django was designed, template developers need little, if any, knowledge of Python and what goes on under the hood with Django requests. I was surprised, however, to see that pure front-end (HTML/CSS/JavaScript) developers were not the target audience of this book:

This book is for web developers and template authors who want to fully understand and utilize the Django ...

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Easy Fabric Deployment, Part 2: Multiple Committers and the Dreaded Umask

October 7, 2009 | code, django | 3 comments

In part 1, we showed how we use Fabric to update and deploy Django sites to our development server with a single command. This works great when you only have one developer pushing changes to the server, but what happens when multiple committers need to update the development server?

Linux File Permissions

Typically, the default permissions for newly created files are readable by everyone and writable by the owner (644 or -rw-r—r—). These permissions are determined by the processes umask, with the default being 022. Since we want multiple committers to be able to write to files on our development server, we need to change that to 002, creating group-writable files (664 or -rw-rw-r—).

The standard way to do this is to add the line umask 002 to /etc/profile. While that works great for interactive shells, it does not get called on non-interactive shells (the kind that ...

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Easy Fabric Deployment, Part 1: Git/Mercurial and SSH

September 22, 2009 | code, django | 3 comments

We’re firm believers in the practices described by the Continuous Integration method of software engineering. Among those are:

• Maintain a code repository
• Automate the build
• Automate deployment

We use git for our code repositories and Fabric to automate our build/deployment process. The tiny bit of overhead it take to write out a Fabric script pays off very quickly against the tedium and error-prone practice of manually building/deploying. In building our “fabfile”, we encountered a couple of issues that took a little head-scratching to work out.

Git and SSH Keys

Git, like Mercurial and others, confirms your credentials via an private/public key pair when used over SSH. We use gitosis to manage our private repositories, so managing everyone’s keys isn’t much of an issue. The problem comes when developers need to start pulling the repository on different machines. Our developers all push to a central ...

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Using Django Inside the Tornado Web Server

September 15, 2009 | code, django | 7 comments

Inspired by Eric Florenzano’s talk, Using Django in Non-Standard Ways (slides in PDF) at DjangoCon and the announcement of Tornado (tornadoweb.org), I decided to try building a small application using the Django Form library and Django ORM inside Tornado. The process proved easier than I expected, especially with Russell Keith-Magee being able to provide guidance on demand.

Step 1: Create Your Database

While Russell explained that it should be possible to get commands like syncdb running outside of a traditional Django project, it was outside the scope of this small experiment. Instead, I created a Sqlite database manually. For those of you that have forgotten how to do this, this will get you started:

# sqlite3 dev.db

sqlite> CREATE TABLE message (id integer primary key, subject varchar(30), content varchar(250));
sqlite> insert into message values(1, 'subject', 'cool stuff');
sqlite> SELECT * from message;

Step 2: Write Your ...

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Customizing the Django Admin at EuroDjangoCon 2009

June 22, 2009 | django, presentation | 2 comments

Last month, Lincoln Loop gave a talk at EuroDjangoCon about customizing the Django admin interface. After presenting some of the admin customizations we had done on Gondola, I had a bunch of people get in touch with me asking me to do a write-up about how it was done. After about 8 months of heel-dragging, I finally took the time to do it in presentation form.

Our talk was divided into two parts. First our User Experience Director, Michael, gave an overview of user interface design and why it is important, pulling examples from some real-world interfaces. Comparing the default Django admin to a custom built application specific interface was an intentional cheap-shot to get people to think outside-the-box when working with the admin. Our argument was that it is possible to recreate any of the example interfaces while still leveraging some of the power baked into django.contrib.admin ...

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Django Best Practices

April 9, 2009 | django | 4 comments

This post got a bit long-winded, skip to the project announcment if you prefer.

One of the things I love about Python and Django is the philosophy that there is one obvious way to do things. Standards make it easy to dive into other people’s code and figure out what is going on pretty quickly. As with anything under active development, however, those standards are subject to change over time. What was best practice for building sites with Django 0.91 is significantly different than building sites with Django 1.0. Better tools and more experience allow us to refine our processes over time into a set of best practices. While both Python and Django are very well documented, much of the experience and wisdom that is outside the scope of the official documentation is not.

Blogs are Bad for Documentation

Most of this information lives scattered across blogs ...

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Satchmo Screencast

December 23, 2008 | django, screencast | 6 comments

Satchmo is an amazing E-Commerce engine built on top of Django. After struggling in the past with difficult packages like ZenCart and OSCommerce, Satchmo’s ease of customization make it a joy to work with.

Unfortunately, all the features can make the administration interface a bit daunting at first glance. I created a screencast to help shop owners get started with the process of adding products and product variations in Satchmo. I’m using the latest release as of this writing (0.8.1).

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Simple & Easy Deployment with Fabric and Virtualenv

December 7, 2008 | django, gondola | 10 comments

In the process of prepping Gondola CMS for public consumption, we’ve grown from having a developer (me), to having a development team. One pain point that quickly arose was the amount of time it took for new developers to setup a local development environment. In addition to our source code, the project depends on nearly a dozen other Django apps and Python packages. Initially, we simply tracked the requirements in a text file, but it required a lot of manual work to get them downloaded and installed.

Necessity is the Mother of Invention

Of course, this problem has been tackled many, many times before¹. As I looked into what was out there, my first thought was that most of the existing options were far too complex for our needs. If I didn’t grok a system after clicking around the docs for 10 minutes or so, I moved ...

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On Static Media and Django

November 13, 2008 | django | 12 comments

We all know not to serve static media (images, CSS, Javascript, etc.) in production directly from Django. Thankfully, Django gives us some nice settings like MEDIA_URL and MEDIA_ROOT to make serving them a lot less painless. Lately, however, I’ve come to realize that these settings shouldn’t really apply to all static media.

Not All Static Media Is Created Equal

Static media really comes in two flavors. Media that is part of your site like your stylesheets and user generated media or files that are uploaded to the site once it is live. We don’t want to serve all this media from the same place for a couple of reasons:

1. Our source checkouts shouldn’t be crufted up by stuff our users are uploading
2. User generated content and source code should live in two different places on the filesystem

We could fix the first problem with some .gitignore ...

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Serving Django Projects (Revisited)

September 22, 2008 | django | 4 comments

After reading the comments on my last post on the subject, I realized there was definitely some room for improvement in my strategy. This is take two of the original post.

Problems

My original strategy had a couple of downfalls:

• Poisoning the Python Path
  I was adding directories to the Python Path that weren’t Python. This raised the chance of namespace collision and just wasn’t a very clean way to do things.
• No project source repository
  I was still storing all my source files in one big folder. Tracking which project is using what was more difficult than it needed to be.

Solutions

The first step to recovery was forgetting about sharing libraries between projects altogether. In theory it sounds great, in practice it was cumbersome to manage. My directory structure now looks like this:

|-domain1.com
|--apache
|---django.wsgi
|--src
|---domain1_project_src
|---third_party_repo1
|---third_party_repo2

This is much cleaner ...

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Introduction to Gondola

September 19, 2008 | django, gondola | 4 comments

Gondola is our content management system built on top of Django. I briefly showed it off during my DjangoCon Lightning Talk, but have been wanting to give it a proper screencast for a while. Here’s an introduction:

A few common questions I don’t tackle in the screencast:

• Is this an open source project?
  As of right now, no. I do plan on spinning off a few bits as open source over time. In fact, the WYSIWYG editor is already on Google Code as django-admin-uploads. Unfortunately it hasn’t been synced up with our in-house code in a while and isn’t working on 1.0. We’ll get that updated at some point in the near future.
• How much will it cost?
  I haven’t settled on a pricing structure yet, but I want it to be affordable for small businesses.
• What version of Django are you running ...

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My Lightning Talk from DjangoCon 2008

September 18, 2008 | django, presentation, trailmapping | 2 comments

DjangoCon was an amazing conference all around. I met some great people and learned a lot. I also had the opportunity to get up on stage and present some of the things I’ve been working on here. I was really nervous and after seeing how well prepared the presenters before me were, I had doubts about my plan to go on stage and wing it. I spoke about Trailmapping and Gondola the CMS I’ve been working on.

Afterwards, I was blown away by the number of compliments I received. A few people told me they thought my talk was the best of the bunch which was really encouraging. To everyone that reached out, all I can say is thanks; it meant a lot. I’m inspired to carve out some more time to blog about the things I’m working on, specifically Django admin customization and jQuery.

Well ...

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Managing Django Projects on Your Server with Style

August 28, 2008 | django | 4 comments

This article is outdated, you’ll find an updated article here.

A friend is in the process of setting up a new slice at everbody’s favorite VPS provider Slicehost and asked for some advice. I use MySQL, Nginx & Apache/mod_wsgi on Ubuntu to serve Django. I think Slicehost’s Articles are awesome and a great place to get help you get everything installed and running, so for this article, I’ll focus on some personal preferences regarding directory structure and repo management.

One of the biggest difficulties I’ve had to tackle lately is the rapid progress of Django. I have a number of client sites hosted on my slice and have had to freeze them at certain times when backwards incompatible changes come along. My original approach made this really messy, because I only accounted for having one copy of any given third party repo, symlinked from /usr ...

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Building a Community Site with Django in 40 Hours or Less

July 20, 2008 | django, trailmapping | 10 comments

All the recent hub bub about 1 week and 1 day application development, motivated me to see how quickly I could launch a website for myself. I, like many developers, struggle with building and releasing personal sites. Ask a web developer and they’re likely to tell you about a couple of sites they started and never finished. Time is always an issue, but the bigger problems are striving for perfection prior to launch and always holding out for that one “killer” feature. As time goes on, interest in the project wanes until it finally gets shelved.

The Plan

Prior to development, I set a few goals for myself:

1. Launching quickly was priority number one. I set a goal of 3 days.
2. Use as much existing code as possible. Even if it wasn’t a perfect fit, if it was functional, use it.
3. Optimize later.
4. Stop scope/feature creep at ...

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Django Newforms Admin Merged to Trunk

July 18, 2008 | django | No comments yet.

This was a huge feat. Congrats guys! 1.0 here we come.

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Django for Hire

June 26, 2008 | company news, django | 3 comments

Lincoln Loop has been in “head down” mode for the last couple months. In addition to being knee deep in client projects, we have grown from a one-man development studio to a full-fledged Django development shop/consultancy. We are proud to announce that Lincoln Loop is the first (that we know of) company focusing solely on Django application development. Our development team is currently five strong and oozing with talent. Each member contributes to the community in blog posts or open source add-ons; a few of us have contributed code to Django itself. More on our dev team in the near future.

We went through the typical growing pains during the transition, but the kinks are worked out and we can officially say that we are open for business. Django projects big and small, send them our way. Our devs can handle nearly anything.

• New Django projects based on your ...

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Getting RequestContext in Your Templates

May 10, 2008 | code, django | 13 comments

Lately, we’ve been taking over projects from people who began building their first site in Django, but either got in over their head or just found they didn’t have the time to continue. As I review the existing code, the first issue I typically see is using the render_to_response shortcut without including the RequestContext, preventing context processors from being used in the templates. The standard symptom is when people can’t access MEDIA_URL in their templates.

Here are a few ways to add RequestContext to your templates.

Option #1: Adding RequestContext to render_to_response

The Django documentation recommends passing RequestContext as an argument to render_to_response like this:

from django.shortcuts import render_to_response
from django.template import RequestContext

def my_view(request):
    # View code here...
    return render_to_response('my_template.html',
                              my_data_dictionary,
                              context_instance=RequestContext(request))

This works, but as you can see, it adds a fair amount of repetitive code to your views ...

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Google App Engine First Impressions

April 8, 2008 | code, django | 2 comments

For those of you that have been hiding under a rock for the last 12 hours, App Engine is Google’s answer to Amazon Web Services. While it is less flexible in some senses (you don’t have a complete OS at your disposal), it does provide tighter integration for web applications and even includes a (somewhat crippled) version of Django out of the box.

I’m pretty excited about this mainly because I’m not a big fan of server administration, so I took a couple hours this morning to test it out. Here are some quick notes:

The Good

• It sort of works with Django
• Deployment is dead simple
• It handles user accounts and registration
• Every app gets a built in Admin Console with stats, version management and datastore CRUD capability
• You can add your own Python libraries
• And, of course, it will scale on the fly

The ...

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Reusable Django Apps and Forking

April 4, 2008 | code, django | 15 comments

One of the things that drew me towards Django was the idea of being able to create reusable applications that would sit on my PYTHONPATH instead of copied across multiple sites. Coming from WordPress, the constant security updates that required me to revisit old projects began to drive me mad.

Trouble in Paradise

With some real world Django experience under my belt, I find myself re-using apps all the time, but not how I originally expected. A fair amount of my client work comes from building content management systems, so I started out building a generic app like flatpages but more extendable and a blogging app. I dropped them in my PYTHONPATH and started adding them to INSTALLED_APPS on my projects.

Over time, they evolved and improved, but they started to handcuff me. I started thinking things like, “This would be a great feature for Project X, but it would ...

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Serving Django via CherryPy

March 25, 2008 | code, django | 13 comments

Background

A few months ago, I got sick of trying to deploy Django sites on my cPanel server and got a VPS at Slicehost. Thanks to SuperJared, setting up Apache/mod_python behind an Nginx frontend was a snap.

I started deploying and migrating sites to the new server and kept an eye on my server resources via Munin. I had about 10 sites running on a 1GB Slice, but the Apache processes were hogging all the RAM. Restarting Apache would bring memory usage down to around 500MB, but within a couple of hours, it would be using all my available RAM, with individual proceesses using as much as 120MB.

I started asking questions and trying different options including mod_wsgi, verifying projects weren’t in debug mode, etc. Nothing made a difference.

CherryPy to ...

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Django FormMail Clone

March 13, 2008 | code, django | 5 comments

Here’s a little nugget I just posted to Django Snippets. It emulates the behavior of an old Perl script I used way back when, FormMail.pl.

I often find myself needing to build a form whose contents get emailed to the site owner(s). This class let’s you call form.notify() on any form that is a subclass of it to have the fields ordered and sent in a plain text email to all users that are flagged as staff.

from django import newforms as forms
from django.contrib.auth.models import User
from django.contrib.sites.models import Site
from django.core.mail import send_mail

class FormMail(forms.Form):
    def notify(self):
        """
        Sends an email to all members of the staff with ordered list of fields
        and values for any form that subclasses FormMail
        """
        site_name = Site.objects.get_current().name
        form_name = self.__class__.__name__
        subject = '%s %s Submission ...

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Better Use of Newforms

March 13, 2008 | code, django | 4 comments

The newforms library is a huge time-saver, but when I first started using it, I still found myself writing tedious repetitve code to get it to function how I wanted. While I could get away with it on smaller sites, I recently built a site with some big forms on it and decided to improve my process.

HTML Rendering

First off, {{ form }} or {{ form.as_p }}, rarely cut it in real world apps. We need to be able to customize our forms to improve the layout or add extra information. I started using inclusion tags to render the form fields and labels. Here is my trivial inclusion tag:

@register.inclusion_tag('_display_field.html')
def display_field(field, alt_label=''):
    """
    Print HTML for a newform field. 
    Optionally, a label can be supplied that overrides the default label generated for the form.
    
    Example:
    {% display_field form.my_field "My New Label" %}
    """

    if alt_label:
        field.label = alt_label
    return { 'field ...

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Cash Offers Fast Site

March 10, 2008 | django, portfolio | No comments yet.

We recently built and launched CashOffersFast.com. It gives people an easy, no-risk way to put their home up for sale. Pre-qualified investors can then make anonymous bids on any home listed with the site.

We worked very closely with the owner of the site to convert his concept into a working web application. From the initial concept, we identified the minimal set of features necessary for the site to function, then took an iterative approach to quickly deliver those features. This allowed the owner to use our working copy for presenting the site to potential investors while we were in the middle of the development cycle.

The site is built in Django and was designed by Derek at ashwebmedia.

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Lincoln Loop Version 2

March 7, 2008 | company news, django | No comments yet.

I’ve been wanting to update my website for quite a while. It got to the point that I wasn’t referring people to my old site because it had become such a poor representation of what Lincoln Loop has evolved into. I’ve also been bottling up a bunch of blogging I want to do about Django for the same reasons.

I set my sights on relaunching before this weekend and my first trip to SXSW. Since I’ll probably do more industry schmoozing there than I have in all the time I’ve been freelancing, I wanted to make sure I had a site I was proud to show off. While the site is still rough around the edges, it is done enough that I am comfortable putting it into production. Once I settle back in, I’m hoping to use this site as a platform to become ...

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Prudential Steamboat Realty

September 28, 2007 | django, portfolio | No comments yet.

A few weeks ago, I released Prudential Steamboat Realty’s new site into the wild. It is my first (but not last) large site built in Django to go live. As usual, ashwebmedia did a great job on redesigning the site and building the user interface.

Prudential gave me the opportunity to scrap their existing property search and build a new one from the ground up. When I’d used local real estate searches in the past, I found them to be pretty poor from a design and user interface standpoint. I took my insight as an end-user along with Prudential’s input to create a more pleasant search experience for their visitors. The initial feedback we have received has been very positive.

In order to keep the search easy to use while still giving “power-users” access to lots of options, I used quite a bit of unobtrusive JavaScript (via ...

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Goodbye WordPress, I'm Leaving You

August 31, 2007 | django, wordpress | Only one comment so far.

WordPress, you seemed perfect at first. You saved me lots of development time, seemed to have a plugin for everything I needed, and a user interface that was easy for anybody to use.

The honeymoon has worn off though. It seems more and more that while you come close, you and your plugins rarely meet my needs. I’ve wasted countless hours fighting to make you do things you just weren’t built to do.

And then there were the upgrades, oh the upgrades. It seemed like every other week I needed to install a new upgrade to make sure you were safe. With every upgrade, I had to make sure the countless plugins you required were all compatible. It all just feels like wasted time now.

I’ve been seeing someone else for a few months now and while it seemed like a harmless fling at first, it has ...

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