QueryBuilder Example

product.rb

class Product < ActiveRecord::Base

  def self.find_by_criteria(params)
    query = where("id IS NOT null") # A little odd but not sure how to get an ActiveRecord::Relation that returns "all"
    query = query.where("price = ?", params[:price]) if params[:price].present?
    query = query.where("manufacturer = ?", params[:manufacturer]) if params[:manufacturer].present?
    query = query.where("retailer = ?", params[:retailer]) if params[:retailer].present?
    query = query.where("category = ?", params[:category]) if params[:category].present?
    query
  end

end

This is what our search ended up looking like: https://gist.github.com/1810085

thoughts on a better way? I'm sure there is...

Lines 11 and 12 were pretty straightforward following your example. It got ugly after that, when we wanted to find the games that matched the ingredients that were checked.

Line 28 is a postgres monstrosity.