Problem

When AR objects are saved, empty fields are saved as '' instead of nil.

Complicates queries for empty fields (WHERE field IS NULL OR field = '')
Makes the use of unless field.blank? necessary (opposed to only if field)
Can lead to late-detected bugs because most of the time strings were filled or '' and suddenly they are nil
Some validations do not support :allow_blank=>true
Databases can handle NULL better & faster than empty strings (especially when using LIKE)

Solution

Defines an AR before_validation that sets empty Strings to nil.

script/plugin install git://github.com/collectiveidea/clear_empty_attributes.git OR
sudo gem install clear_empty_attributes

When you are switching to clear_empty_attributes, run this task to remove any '' strings/texts from your database.

rake db:clear_empty_attributes

(only works when checked out or installed as plugin)

Hereby placed under public domain, do what you want, just do not hold anybody accountable...