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好的，我有一个卡车装载板，卡车司机可以在那里张贴可用的卡车。我有卡车张贴。但是在设置搜索功能以及我需要关联不同表的方式时遇到问题。

Rails 3
postgres

gem 'geokit-rails'

我现在拥有的方式是我有一个位置表设置，例如：

 class Location < ActiveRecord::Base

  attr_accessible :cs, :lat, :lon, :city, :state

  acts_as_mappable :default_units => :miles,
                   :default_formula => :sphere,
                   :distance_field_name => :distance,
                   :lat_column_name => :lat,
                   :lng_column_name => :lon

当有人发布卡车时，它具有起点和终点。所以它有 2 个位置，并且设置如下：

class Truck < ActiveRecord::Base
  attr_accessible :available, :company_id, :dest_id, :origin_id, :equipment, :origin, :dest
  belongs_to :origin, class_name: "Location", foreign_key: :origin_id
  belongs_to :dest, class_name: "Location", foreign_key: :dest_id
  belongs_to :company

通过我设置它的方式，我可以从以下位置获取位置信息：

Truck.find(1).origin  || Truck.find(1).dest

它将返回与其关联的位置记录

现在我的问题是我希望能够编写一个搜索函数来查找距离原点“给定”英里数内的任何卡车|| 目的地 || 出发地和目的地

我知道我能做到Location.within(25, :origin => "Springfield, Mo")，它会搜索所有位置并返回 Springfield Mo 25 英里范围内的位置

但是我将如何在有 2 个位置（起点和终点）并且它们与位置 ID 相关联的卡车上使用它。

我目前有一些其他搜索参数已经编码并且正在工作，只是不确定如何将其合并到其中：

def search(search)
    where = []
    where << PrepareSearch.states('dest', search.dest_states) unless search.dest_states.blank?
    where << PrepareSearch.states('origin', search.origin_states) unless search.origin_states.blank?
    where << PrepareSearch.location('origin', search.origin_id, search.radius) unless search.origin.blank?
    where << PrepareSearch.location('dest', search.dest_id, search.radius) unless search.dest.blank?
    where << PrepareSearch.equipment(search.equipment) unless search.equipment.blank?
    where << PrepareSearch.date('available', search.available, '<') unless search.available.blank?
    where = where.join(' AND ')
    Truck.where(where)
  end


module PrepareSearch
    def PrepareSearch.location(type, location, radius)
      loc = Location.find(location)

   *type will be origin/destination Location active record
   *location will be Location id
   *radius will be a given mileage

**This is where i need to figure out what to put here**

    end
end

将方程式合并起来会更好：

 def sphere_distance_sql(origin, units)
    lat = deg2rad(origin.lat)
    lng = deg2rad(origin.lng)
    multiplier = 3963.1899999999996 # for miles

    sphere_distance_sql(lat, lng, multiplier)
  end
  def sphere_distance_sql(lat, lng, multiplier)
    %|
      (ACOS(least(1,COS(#{lat})*COS(#{lng})*COS(RADIANS(#{qualified_lat_column_name}))*COS(RADIANS(#{qualified_lng_column_name}))+
      COS(#{lat})*SIN(#{lng})*COS(RADIANS(#{qualified_lat_column_name}))*SIN(RADIANS(#{qualified_lng_column_name}))+
      SIN(#{lat})*SIN(RADIANS(#{qualified_lat_column_name}))))*#{multiplier})
     |
  end
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1 回答 1

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好吧好吧，我已经找到了解决问题的方法……如果有更好的解决方案，我很想知道。

where << PrepareSearch.location_ids("origin", search.origin, search.radius) unless search.origin_id.blank?
where << PrepareSearch.location_ids("dest", search.dest, search.radius) unless search.dest_id.blank?


def PrepareSearch.location_ids(type, location, radius)
  if location.nil?
    return nil
  else
    loc = Location.find(location)
    location(type, loc, radius)
  end

end

def PrepareSearch.location(type, location, radius)
  locs = Location.within(radius, :origin => location.cs).pluck(:id)
  st = ""
  locs.each {|s| st += "'#{s}'," }
  st = st[0..-2]
  "#{type}_id IN (#{st})"
end
于 2014-12-30T21:24:01.533 回答