MongoMapper 靠近 maxDistance - Mongo::OperationFailure：地理值必须是数字：

我试图在 MongoMapper 支持的模型中封装一个带有 maxDistance 的近查询。

我一定在我的查询语法中做了一些愚蠢的事情。

Model

class Site
  include MongoMapper::Document

  key :id, Integer 
  key :name, String
  key :location, Array
  ensure_index [[:location, '2d']]


  def self.nearest(center_point, range)
    where(:location => {'$near' => center_point, '$maxDistance' => range}).all
  end

end

试图让所有东西都在一个点的 200 英里范围内......

站点.nearest([-122.0,44.0],200)

> Mongo::OperationFailure: geo values have to be numbers: {
> $maxDistance: 200, $near: [ -122.0, 44.0 ] }  from
> /Library/Ruby/Gems/1.8/gems/mongo-1.6.1/lib/mongo/cursor.rb:144:in
> `next'    from
> /Library/Ruby/Gems/1.8/gems/mongo-1.6.1/lib/mongo/cursor.rb:290:in
> `each'    from
> /Library/Ruby/Gems/1.8/gems/mongo-1.6.1/lib/mongo/cursor.rb:308:in
> `to_a'    from
> /Library/Ruby/Gems/1.8/gems/mongo-1.6.1/lib/mongo/cursor.rb:308:in
> `to_a'    from
> /Library/Ruby/Gems/1.8/gems/plucky-0.4.4/lib/plucky/query.rb:74:in
> `all'     from /Users/nick/Code/web/map/app/models/site.rb:40:in
> `nearest'     from (irb):

你可能遇到过this bug https://jira.mongodb.org/browse/SERVER-1990这需要$near and $maxDistance订购时$maxDistance first.

无论如何，我发现这个问题是因为我得到了OperationFailure: database error: geo values have to be number使用 PyMongo 时，交换顺序修复了它。