Using MySQL reserved words as model names

The generation of a model with a migration in a ruby on rails application lets to the creation of a database table with the pluralization form of the desired model name. In MySQL, a migration will generate a sql statement like:

CREATE TABLE model_name_pluralized (`id` int(11) DEFAULT NULL auto_increment PRIMARY KEY,
 `created_on` date DEFAULT NULL, `name` varchar(255) DEFAULT NULL) ENGINE=InnoDB

As you can notice column names are quoted but table name doesn't. If you use as a model name a sigularized form of a MySQL reserved word, the migration that creates this model will generate a statement that will lead to an error like:

Mysql::Error: You have an error in your SQL syntax; check the manual that corresponds to your
 MySQL server version for the right syntax to use near 'databases (`id` int(11) DEFAULT NULL 
auto_increment PRIMARY KEY, `created_on` da' at line 1: CREATE TABLE databases (`id` int(11) 
DEFAULT NULL auto_increment PRIMARY KEY, `created_on` date DEFAULT NULL, `name` varchar(255)
 DEFAULT NULL) ENGINE=InnoDB

Last week I read the Josh Susser Laying Tracks slides who
encourages me to write a patch for this issue.

Before writing anything I tried to find if someone has made something related and I found some tickets related in Rails trac:

• #7850: [PATCH] Added missing backticks to mysql adapter


• #4905[PATCH] Rails should backtick table names automagically


• #3631: table names should be quoted


• #1633: [PATCH] quote_column_name in ActiveRecord::ConnectionAdapters ...

The most interesting of this tickets is #4905 which fix all MySQL statements to prevent reserved words crash, but I don't know why isn't included in the code because it's last history is from 05/25/2006. #7850 is closed as duplicated because of #4905. And #3631 history finishes with "don't use reserved words" what in my opinion isn't the best solution.

In brief, the problem exists (I can't name my models with names like "database", "exist", ...) and the patch too (#4905). Then, what should we do to fix this problem?

Backup of Bloglines keep new items

If you are a Bloglines user, you probably save the interesting posts using "keep new" feature.

If you have use this reader for a time, the quantity of post saved could be large... Some day I thought that won't be funny to loose all this data, then I build a ruby script to backup bloglines "keep new" items into a xml file.

With this script I learned better Mechanize and Hpricot Ruby libraries.
Este script me ha servido para probar dos librerías muy útiles de Ruby: mechanize y hpricot.

You need these libraries in order to use the script:

gem install json
gem install activesupport
gem install hpricot
gem install mechanize

And here you have the script. I think is very understandable. I hope it helps you to backup your bloglines account (remember to change EMAIL and PASSWORD values with yours) or to understand better how mechanize and hpricot works.

require "rubygems"
require "hpricot"
require "json"
require "mechanize"
require "active_support"

# Reads a bloglines javascript tree structure that has all
# feeds data.
def read_tree( tree_base, label = "" )
 tree_base.each do |tree|
 if tree["kids"]
  read_tree tree["kids"], label + "/" + tree["n"]
  else
  @feeds << [tree["n"], label, tree["kn"], "http://www.bloglines.com/myblogs_display?sub=#{tree["id"]}&site=#{tree["sid"]}"]
 end
 end
end

# Add more memory to hpricot otherwise couldn't load some webs.
Hpricot.buffer_size = 262144

agent = WWW::Mechanize.new
page = agent.get 'http://www.bloglines.com/login'

form = page.forms[1]
form.email = 'EMAIL'
form.password = 'PASSWORD'

page = agent.submit form

# Get the bloglines sindicated feeds
menu_page = agent.get "http://www.bloglines.com/myblogs_subs"
start_text = "var initTreeData = "
end_text = "\n;\n"
js_feeds_tree_str = menu_page.content[menu_page.content.index(start_text)+start_text.size..menu_page.content.index(end_text)]
feeds_tree = JSON.parse js_feeds_tree_str.gsub("\\","")
@feeds = []
read_tree(feeds_tree["kids"])

puts "<bloglines_saves>"
@feeds.each do |feed|

 page = agent.get feed[3]
 doc= Hpricot(page.content)

 # get the content of all saved feed posts
 content = ((doc/"body")/"td.article")
 next if content.empty?
 puts "<feed name=\"#{feed[0].strip}\" folder=\"#{feed[1].strip}\">"
 
 # Iterate each saved feed post
 ((doc/"body")/"a.bl_itemtitle").each_with_index do |title, index|
  puts "<feed_save title=\"#{title.inner_html.strip}\" href=\"#{title.attributes["href"]}\">"
  puts content[index].inner_html.to_xs
  puts "</feed_save>"
 end
 puts "</feed>"

end
puts "</bloglines_saves>"

Más información:

• Hpricot: http://code.whytheluckystiff.net/hpricot/
• Mechanize: http://mechanize.rubyforge.org/mechanize/

General Genetic Algorithms for Ruby (gga4r) release 0.9

General Genetic Algorithms for Ruby (gga4r) is a library for executing generic algorithms easily.

Only 3 steps are needed in order to work with gga4r:

1. Choose a clase to evolve and define for her the fitness, combine and mutate methods.


2. With an array of last defined class instances (initial population), create a GeneticAlgorithm object.


3. Call GeneticAlgorithm's evolve method as many times as you want.

More info:

• gga4r website: http://gga4r.rubyforge.org


• gga4r rubyforge project: http://rubyforge.org/projects/gga4r


• gga4r spanish site: http://gga4r.rubyforge.org/es

DEISA Sessions (Distributed European Infrastructure for Supercomputing Applications)

This week I'm taking DEISA training sessions in Barcelona, they are teaching us how to submit tasks into most powerful supercomputers of Europe (DEISA Architecture).

Within this supercomputers we can meet Marenostrum, nowadays is the most powerful supercomputer in Europe and the World's fifth most powerful as you can see in www.top500.org. It's made of 10.240 CPUs Power PCs, 20 TeraBytes of RAM and 370 TeraBytes of disk. It's placed in a old chapel which gives it a special feeling.

Today I've been lucky and I could visit inside Marenostrum as you can see in this photos:







More photos: http://www.flickr.com/photos/spejman/tags/marenostrum/

Bayesian Networks for Ruby release 0.9

Bayesian Networks for Ruby (bn4r) permits create, modify, solve, import and export Bayesian Networks, give it a try and infer some probabilities with them!

This release includes suport for discrete variable nodes, now you can use nodes with values like {small, normal, big} instead of {true, false}.

Export to Microsoft Belief Network has been improved.

As previous releases you can solve your networks with enumeration_ask, prior_sample, rejection_sampling and likelihood_weighting algorithms.

Testing work will be appraised, if you are interested please contact me in http://rubyforge.org/projects/bn4r or at sergio.espeja (you know what ...) gmail.com.

More info:

• bn4r Website: http://bn4r.rubyforge.org
• bn4r Rubyforge project: http://rubyforge.org/projects/bn4r
• bn4r spanish website: http://bn4r.rubyforge.org/es