使用acts_as_mappable

Question

为了方便起见，我有一个只想使用.within等的类。

这就是我所做的。

# This is the class i want the scopes on
class Thing < ActiveRecord::Base
  has_one :location, :as => :locatable
  acts_as_mappable :through => :location
end

# My Location class
class Location < ActiveRecord::Base
  belongs_to :locatable, :polymorphic => true
  acts_as_mappable :default_units => :miles,
                   :default_formula => :sphere,
                   :distance_field_name => :distance,
                   :lat_column_name => :lat,
                   :lng_column_name => :lng

  validates :lat , numericality: { greater_than_or_equal_to:  -90, less_than_or_equal_to:  90 }
  validates :lng, numericality: { greater_than_or_equal_to: -180, less_than_or_equal_to: 180 }

end

无论出于何种原因，我都无法在Thing上使用act_as_mappable范围。

NoMethodError: undefined method `within' for #<Thing:0x007f9a561cecb8>

但是我可以使用Location.within（N，location）