How to convert postgresql column into a float for a scoped search in rails
===

I am trying to search my postgresql db in rails. I followed the <a href="http://railscasts.com/episodes/111-advanced-search-form-revised">Railscasts #111 Advanced Search</a> tutorial and it is working for the name and category of my items column in plain text. However, I want to set a min/max price on my search as well which is where I come into my problem. In my db my price is stored as a string in the format "AU $49.95". Can I convert this into a float on the fly in my scoped search? If so how? If not, what should I do?

Here is the code:

search.rb

    class Search < ActiveRecord::Base
      attr_accessible :keywords, :catagory, :minimum_price, :maximum_price
    
    	def items
    	  @items ||= find_items
    	end
    
    	private
    
    	def find_items
    	  scope = Item.scoped({})
    	  scope = scope.scoped :conditions => ["to_tsvector('english', items.name) @@ plainto_tsquery(?)", "%#{keywords}%"] unless keywords.blank?
    	  scope = scope.scoped :conditions => ["items.price >= ?", "AU \$#{minimum_price.to_s}"] unless minimum_price.blank?
    	  # scope = scope.scoped :conditions => ["items.price <= ?", "AU \$#{maximum_price.to_s}"] unless maximum_price.blank?
    	  scope = scope.scoped :conditions => ["to_tsvector('english', items.catagory) @@ ?", catagory] unless catagory.blank?
    	  scope
    	end
    
    end

searches_controller.rb

    class SearchesController < ApplicationController
      def new
        @search = Search.new
      end
    
      def create
        @search = Search.new(params[:search])
        if @search.save
          redirect_to @search, :notice => "Successfully created search."
        else
          render :action => 'new'
        end
      end
    
      def show
        @search = Search.find(params[:id])
      end
    end

Thanks for reading this far!