Hexaflexamaps

Looking through a very old copy of Martin Gardner’s Mathematical Games, I stumbled upon his article about Flexagons and thought “what would these look like with maps on them?”. This is what they look like (at a really low resolution), but it is much more fun to make your own…

Video of hexaflexamap flexing.
(more…)

November 12th, 2008 - Posted by Matt Amos in ruby, tips | | 4 Comments

MiniBar / WhereCamp Slides

Here are the slides to accompany the presentaion given at MiniBar on the 25th May. We gave a similar version of the presentation as a lightening talk at WhereCamp, in Sunnyvale CA on the 2nd June. Enjoy!

June 8th, 2007 - Posted by in REST, api, ruby, ruby on rails, tools | | 0 Comments

Add Custom SQL to Rails Active Record Migrations

Ruby on Rails’ Migrations offer a nice alternative to traditional SQL DDL statements, that fit in with the Rails agile development philosophy. Migrations let you use Ruby code to create, alter and drop databases and tables, allowing you, amongst other things to switch databases mid-development, without having to refine your SQL.

Such convenience can sometimes mean a lack of flexibility. If you are trying to add a column to a MySQL database with type bigint unsigned, you’ll run into problems as ActiveRecord does not support unsinged bigints. You can solve the problem with some creative use of Ruby’s command line execution features - any code in a ruby file that is included between backticks(’ ` ‘) will be executed as a command line argument - so now you can include custom SQL statements without losing the benefits of Migrations:

class MyClass < ActiveRecord::Migration
  def self.up
    remove_column :mytable, :old_column
    puts `mysql database -u user -ppassword
    -e 'alter table mytable add column new_column bigint unsigned'`
  end
..
..
end

April 10th, 2007 - Posted by in ruby, ruby on rails, tips | | 0 Comments