ruby-on-rails - Geokit plus Rails 3.1.1，纬度和经度问题。

Question

我正在使用 geokit-rails3 gem 在特定大学范围内的所有大学中查找产品。一个学院有很多产品，一个产品属于学院，还有一个类别模型有很多产品，产品属于类别。但是，当我尝试使用 geokit 根据 addess 从数据库中查找大学时，它告诉我我的表中缺少 lat coloumn。

高校迁移是

 create_table :colleges do |t|
  t.string :name
  t.text :address
  t.string :city
  t.string :state
  t.integer :zipcode

  t.timestamps

Controller

     @products = College.within(5, :origin=>@current_product.college.address).product

错误:

     Mysql::Error: Unknown column 'colleges.lat' in 'field list': SELECT `colleges`.*, 
      (ACOS(least(1,COS(0.3223824452162744)*COS(1.2891920858347756)*COS(RADIANS(colleges.lat))*COS(RADIANS(colleges.lng))+
      COS(0.3223824452162744)*SIN(1.2891920858347756)*COS(RADIANS(colleges.lat))*SIN(RADIANS(colleges.lng))+
      SIN(0.3223824452162744)*SIN(RADIANS(colleges.lat))))*3963.19)
      AS distance FROM `colleges`  WHERE ((colleges.lat>18.398868573573203 AND colleges.lat<18.543438426426793 AND colleges.lng>73.78905443427034 AND colleges.lng<73.94147656572967)) AND ((
      (ACOS(least(1,COS(0.3223824452162744)*COS(1.2891920858347756)*COS(RADIANS(colleges.lat))*COS(RADIANS(colleges.lng))+
      COS(0.3223824452162744)*SIN(1.2891920858347756)*COS(RADIANS(colleges.lat))*SIN(RADIANS(colleges.lng))+
      SIN(0.3223824452162744)*SIN(RADIANS(colleges.lat))))*3963.19)
      <= 5))

任何提示如何解决这个问题？

Answer 1

任何 acts_as_mappable with geokit 都需要一个 lat & lnt 字段(这些可以使用不同的名称覆盖)

查看顶部:http://geokit.rubyforge.org/readme.html

我建议:

add_column :colleges, :lat, :float
add_column :colleges, :lng, :float
add_index  :colleges, [:lat, :lng]

此外，要自动更新地址:

before_save :update_location

def update_location
 #you probably you to use a full address, or join all the address parts instead of just self.address
 loc=Geocoder.geocode(self.address)
 if loc.success
   self.lat = loc.lat
   self.lng = loc.lng
 end
end