How can I search date range in Rails with variable date

Question

How can I do this in rails active record¿?

find all models that match (created_at + 100 days between this month)

Edit: Ok, Sorry for not be precise this what

Answer 1

In Rails 3 you can use:

YourModel.where(:created_at => start_date..end_date)

where start_date and end_date are Date class.