DSL configuration in activerecord model in Rails 3

I want to generate reports for some database data. I store report settings in a database using activerecord models, but I don't want that, I want to write something like

class Department < ActiveRecord::Base
    ...
    report do
        name   "Total Sales by Departments"
        method :name

        report_field do
            name     "Total Sales"
            action   :sum
            relation "Sales"
            method   :spent
        end

        report_field do
            name     "Average Sales"
            action   :avg
            relation "Sales"
            method   :spent
        end
    end
end

      

        
        
        
      

    

Can someone please tell me how this can be done and what should I read, maybe some examples of other things similar to my problem?