def stringify_params(conditions)
      return conditions unless conditions.is_a?(Hash)
      conditions.each do |k, v|
        conditions[k] = v.to_s if param_requires_string_conversion?(v)
      end
    end
def stringify_params(conditions)
      return conditions unless conditions.is_a?(Hash)
      conditions.each do |k, v|
        conditions[k] = v.to_s if param_requires_string_conversion?(v)
      end
    end
Force keys to be string to avoid injection on mongoid related database.