Calendar quarter calculations in Ruby and MySQL
ActiveSupport >= 3 has
Date.parse('2011-02-10').beginning_of_quarter #=> 2011-01-01
Date.parse('2011-02-10').end_of_quarter #=> 2011-03-31
You can manually calculate the quarter index like
(Date.parse('2011-02-10').month / 3.0).ceil #=> 1
Yes, you do actually divide by 3.0
, not 4.0
.
MySQL has
SELECT QUARTER('2011-02-10'); #=> 1
Related cards:
The Ruby Object Model
In Ruby (almost) everything is an Object
. While this enables a lot of powerful features, this concept might be confusing for developers who have been programming in more static languages, such as Java or C#. This card should help understanding t...
The JavaScript Object Model: A deep dive into prototypes and properties
Speaker today is Henning Koch, Head of Development at makandra.
This talk will be in German with English slides.
Introduction
As web developers we work with JavaScript every day, even when our backend code uses anothe...
Lightning Talk: Coverage based Test Case Prioritization in Ruby on Rails
For my computer science bachelor's thesis I programmed and evaluated a CLI Test Case Prioritization (TCP) tool for makandra. It has been written as a Ruby Gem and was tested and evaluated against one Ruby on Rails project....
instance_eval behaves different in Ruby 1.8 and Ruby 1.9, use instance_exec instead
In Ruby 1.9, instance_eval
calls the block the with receiver as the first argument:
- In Ruby 1.8,
receiver.instance_eval(&block)
callsblock.call()
- In Ruby 1.9,
receiver.instance_eval(&block)
callsblock.call(receiver)
This will blo...
MySQL: How to create columns like "bigint" or "longtext" in Rails migrations, and what :limit means for column migrations
Rails understands a :limit
options when you create columns in a migration. Its meaning depends on the column type, and sometimes the supplied value.
[The documentation](http://apidock.com/rails/ActiveRecord/ConnectionAdapters/TableDefinition/co...
Differences between transactions and locking
Web applications can be used by multiple users at the same time. A typical application server like Passenger has multiple worker processes for a single app. In a distributed deployment setup like we use at makandra you w...
How to create giant memory leaks in AngularJS (and other client-side JavaScript)
This guide shows how to create an AngularJS application that consumes more and more memory until, eventually, the browser process crashes on your users.
Although this guide has been written for Angular 1 originally, most of the advice is relevant...
CarrierWave: Processing images with libvips
When you write your next CarrierWave uploader, consider processing your images with libvips instead of ImageMagick.
Reasons for libvips
There are several **upsi...
How to make changes to a Ruby gem (as a Rails developer)
At makandra, we've built a few gems over the years. Some of these are quite popular: spreewald (> 1M downloads), active_type (> 1M downloads), and geordi (> 200k downloads)
Developing a Ruby gem is different from developing Rails applications, w...
Understanding SQL compatibility modes in MySQL and MariaDB
MySQL and MariaDB have an SQL mode setting which changes how MySQL behaves.
The SQL mode value is comprised of multiple flags like "STRICT_TRANS_TABLES, NO_ZERO_IN_DATE"
. Each flag activa...