With the  clear_empty_attributes plugin, all empty string worries are gone!

• Complicate queries for empty fields (WHERE field IS NULL OR field = '')
• Use of unless field.blank? (opposed to only if field)
• Late-detected bugs because most of the time columns were filled or '' and suddenly they are nil
• Some validations do not support :allow_blank=>true
• Datebases can handle NULL better & faster than '' (especially when using LIKE)

Install

script/plugin install git://github.com/grosser/clear_empty_attributes.git

Now all empty strings will be saves as NULL.

Migrate

To take care of all other/old models we have to run a migration.
Remove any blank strings/texts from your Models:

rake clear_empty_attributes:clear_all_blank_strings MODELS=User,Movie,...