• Dec 24, 2006

  Seen elsewhere: Glue sniffers on Singapore train

  Tomorrow.sg has an entry with a photo of glue sniffing girls on a MRT train. This picture is tits (as Eric Cartman would say).

• Dec 22, 2006

  Mind your MySQL update syntax

  Just noticed an insidious "bug" in MySQL when you use "AND"s instead of commas to separate the fields you are updating in your SET clause. Being a little rusty in SQL, I entered something like the query below while trying to make a quick fix to some records:

  UPDATE characters
  SET alignment = 'Neutral Evil'
  AND last_name = 'Majere'
  WHERE first_name = 'Raistlin'

  Much to my consternation, the record appeared to have disappeared when I tried to query for it. After much bewildered cursing, I came across MySQL bug #15928: update syntax error not detected (this is not an actual bug though). As it turns out, MySQL does a logical AND and the result is that the 'alignment' field is set to '0' since 'Neutral Evil' AND last_name = 'Majere' results in false. And MySQL casts it to '0'. Grrr. Luckily I was able to revert the changes by finding the record again with the new '0' alignment value (was using an auto-committing MySQL GUI client, no ROLLBACK available).

• Dec 19, 2006

  Firefox Secrets on Google Book Search

  A GoogleAlert (not the Google Alert) email arrived in my inbox today alerting me to the Firefox Secrets entry on Google Book Search (that's a book I wrote, for the uninitiated). It's listed as a limited preview so only the first few pages of each chapter are available. If you're interested in previewing a Firefox book circa 2005 (virtually the Mesozoic ages in the tech world), just maybe, check it out.

• Dec 14, 2006

  HP laptop with an Apple sticker

  Saw this in a MacDonald's at a local shopping mall:

  

  
  

  If you can look past the fuzziness of the photo, it's actually someone using a HP laptop with an Apple sticker. Now, if only I can get a HP sticker for my MacBook Pro...

• Dec 4, 2006

  Adding full text search to your Rails app in 1 hour and 10 lines of code

  Yup, it's that fast and simple, using Ferret, a Ruby port of Lucene (the de facto full text search engine written in Java) and the acts_as_ferret plugin, I added "Did you mean this?" functionality to a small Rails application (non-perma link) today rather quickly and painlessly.

  Adding full text search funtionality to your Rails applications

  Install Ferret via RubyGems.
  sudo gem install ferret

  Install the acts_as_ferret plugin for your Rails application.
  ruby script/plugin install <ACTS_AS_FERRET_SVN_REPOSITORY>

  Add the acts_as_ferret mixin method to your ActiveRecord model, specifying the fields you want indexed.

  class Location < ActiveRecord::Base
    belongs_to :country, :foreign_key => 'country_code'
    belongs_to :state
  
    acts_as_ferret :fields => [:location_name, :country_name, :state_name]
  
    def country_name
      country.country_name
    end

  If you have any associations that you want searched as well, one way (there is more than one way to do this) would be like what I did above with the country_name attribute of Country. For a more detailed discussion on Ferret and ActiveRecord associations, I found this thread in the Ruby forum enlightening.

  In your controller, use Model.find_by_contents() to perform the full text search with your query. If you need fuzzy matching, append a tilde ("~") to the end of your query - if you're here, you probably needed fuzzy matching anyway as you're most likely creating "Did you mean this?"-type functionality.

  # In the controller...
  @locations = Location.find_by_contents("#{@search_request.location_entered}~") # The "~" is for fuzzy matching.
  

  All that's left is to flash the appropriate message in your view and display your model objects as you normally would.

  Some gotchas:

  • If you change the way your model is indexed, remember to clear out the existing one. acts_as_ferret stores the index by default in a 'index/' directory in the root of your Rails application. Stop your mongrel/Webrick process to remove the lock on the index files and delete the whole directory - Ferret will rebuild it the next time you perform a full text search.
  • The first time you do a full text search, Ferret builds your index for you and this takes quite a while - don't be alarmed if your Rails application appears for freeze or returns a 500 internal server error. You can observe the contents of the 'index/' directory in the root of your Rails application to tell when Ferret has finished indexing (files stop appearing and disappearing). I found it easier to run a 'find_by_contents' call on my models via 'script/console' and waiting for some results to appear.
  • Append a "~" to your query string for fuzzy matching! This allows you to retrieve results matching phonetically or are mispelled. There are more complex matching rules - check out the Lucene documentation.

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