Searchable serialized fields

Hi everyone

Recently I thought about adding a feature that allows to find records
by values in a serialized field. For example:

class Article < ActiveRecord::Base
  serialize :parameters, Hash
end

let's create a sample article to search for:

article = Article.new
article.title = 'Sample article'
article.parameters = {:foo => "bar"}
article.save

and then when if we wanted to find that article by its :foo value we
could do something like that:

article = Article.where(:parameters => {:foo => "bar"})

Of course the syntax is just an example, not sure how could that look
if implemented.

This would require a database-sided use of regular expressions. But
more importantly, would that feature have a use in Rails?

If you serialize as xml instead of yaml, you can make use of xml query
functions if your database supports them... mysql and postgres do at
least.

This kind of ad-hoc fields, and nested searching is well suited to mongo if you can use it…