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I'm developing a rails app where Users are having many Items. The users are geocoded thanks to another model I called Place that is relying on the ruby geocoder gem.

class Place < ActiveRecord::Base
    attr_accessible :street_number, :street, :city, :postal_code, :country, :latitude, :longitude

    belongs_to :placable, :polymorphic => true
    geocoded_by :address
    after_validation :geocode

    def address
       [street_number, street, postal_code, city, country].compact.join(', ')
   end
 end

In the user model, I delegated methods from the Place model to be able to access them directly at the user level.

class User < ActiveRecord::Base
  has_many :items, :dependent => :destroy
  has_one  :place, :as => :placable, :dependent => :destroy
  accepts_nested_attributes_for :place
  attr_accessible :place_attributes

  geocoded_by :address
  delegate :address, :to => :place, :allow_nil => true
  delegate :latitude, :to => :place, :allow_nil => true
  delegate :longitude, :to => :place, :allow_nil => true
  #...
end

The same trick is used at the items level:

class Item < ActiveRecord::Base
  belongs_to :user

  # place
  geocoded_by :address
  delegate :place, :to => :user, :allow_nil => true 
  delegate :address, :to => :user, :allow_nil => true
  delegate :latitude, :to => :user, :allow_nil => true
  delegate :longitude, :to => :user, :allow_nil => true
  # ...
end

Now I'd like to set up an index on items such that they are sorted by distance to the current user. I don't find a design to perform the task in this setup.

I tried to do the following with the delegation of the near method from geocoder on the User model and the Itemmodel but the sql query fails complaining that latitude and longitude are not columns of the items table. This is actually correct but I wish to access the ones in the placestable instead.

  # this added to the user model:
  delegate :near :to => :place
  # this added to the item model:
  delegate :near :to => :user

  class ItemsController < ApplicationController

    def index
       @items=Item.near(current_user.place, params[:distance]).paginate(:per_page => 20, :page => params[:page_name])
    end
  end

I would like to avoid the solution where both users and items are having attributes for geocoding (latitude, longitude, address, etc.).

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1 回答 1

-1

我不知道这对我来说是太明显还是我错了，但请允许我尝试：

我只需创建一个列（例如，位置 - 在项目模型处）来保存项目的当前位置，然后将其与当前用户位置进行比较。

不是你要找的吗？希望我有帮助！

于 2013-09-25T11:50:32.407 回答