Database

We regularly use tools like PostgreSQL, Pandas, and Jupyter Notebooks to analyze data here at Caktus. Recently, we were reviewing North Carolina traffic stop data for the NC CopWatch project and had the opportunity to use PostgreSQL's window functions, which are helpful when aggregating data.

I recently decided I wanted to understand better what Cross-Site Scripting and Cross-Site Request Forgery were, and how they compared to that classic vulnerability, SQL Injection.

Here’s external links our team’s been chatting about and sharing on social media since the last roundup.

Web Service Efficiency at Instagram with Python (Instagram)

“Instagram currently features the world’s largest deployment of the Django web framework, which is written entirely in Python. We initially chose to use Python because of its reputation for simplicity and practicality, which aligns well with our philosophy of ‘do the simple thing first.’”

This Thursday, Colin Copeland, CTO and Caktus Group Co-founder, will be co-presenting “Case Study from North Carolina: Identifying Racial Bias in Policing Practices” during the prestigious 2015 Code for America Summit in Oakland, CA. This invite-only event joins technologists, activists, and officials ranging from mayors to White House officials to discuss technology’s role in civic participation.

We are always looking for ways to make our tests run faster. That means writing tests which don't preform I/O (DB reads/writes, disk reads/writes) when possible. Django has a collection of TestCase subclasses for different use cases. The common TestCase handles the fixture loading and the creation the of TestClient. It uses the database transactions to ensure that the database state is reset for every test. That is it wraps each test in a transaction and rolls it back once the test is over. Any transaction management inside the test becomes a no-op. Since [TestCase]{.title-ref}[ overrides the transaction facilities, if you need to test the transactional behavior of a piece of code you can instead use ]{.title-ref}[TransactionTestCase]{.title-ref}[. ]{.title-ref}[TransactionTestCase]{.title-ref}` resets the database after the test runs by truncating all tables which is much slower than rolling back the transaction particularly if you have a large number of tables.

I'm delighted to announce that we've just published another job posting for a Linux Systems Administrator at Caktus. The position will involve maintaining existing Linux servers, designing and building highly-scalable deployments, and assistance with Django deployment and development as time permits. This is a full-time position, with benefits, and is based out of our Carrboro, NC office (a short drive from Raleigh, Durham, and Chapel Hill).

Django's ORM is great. It handles simple to fairly complex queries right out the box without having to write any SQL. If you need a complicated query, Django's lets you use .extra(), and you can always fallback to raw SQL if need be, but then you lose the ORM's bells and whistles. So it's always nice to find solutions that allow you to tap into the ORM at different levels.

In Django, a recursive many-to-many relationship is a ManyToManyField that points to the same model in which it's defined ('self'). A symmetrical relationship is one in where, when a.contacts = [b], a is in b.contacts.

We're in the process of updating a web app for a client that was built last year about this time using Django and Photologue. Needless to say, there have been a lot of changes to both over the past year!

Here at Caktus, we use the popular Django web framework for a lot of our custom web application development. We don't use Django simply because it's popular, easy to learn, or happened to be the first thing we found. We've written web apps in PHP, Java, and Ruby on Rails--all before we discovered Django--but were never quite satisfied. Following are just a few of the reasons that we both enjoy working with Django and believe it gives you (the client) the best end-product.