Question

我有以下自定义字段类型，允许我保存GeoJSON LineString，同时将字段视为点数组：

class GeoLineString

  attr_reader :coordinates

  def initialize(array)
    @coordinates = array
  end

  # Converts an object of this instance into a database friendly value.
  def mongoize
    {
        "type" => "LineString",
        "coordinates" => @coordinates
    }
  end

  def as_json(options={})
    mongoize
  end

  class << self

    # Get the object as it was stored in the database, and instantiate
    # this custom class from it.
    def demongoize(object)
      return self.new(object["coordinates"]) if object.is_a?(Hash)
    end

    # Takes any possible object and converts it to how it would be
    # stored in the database.
    def mongoize(object)
      case object
        when GeoLineString then object.mongoize
        when Array then GeoLineString.new(object).mongoize
        else object
      end
    end

    # Converts the object that was supplied to a criteria and converts it
    # into a database friendly form.
    def evolve(object)
      case object
        when GeoLineString then object.mongoize
        else object
      end
    end
  end
end

我在我的模型中使用如下：

class Track
  include Mongoid::Document
  include Mongoid::Timestamps

  field :name, type: String
  field :coordinates, type: ::GeoLineString
  index({ coordinates: "2dsphere" }, { min: -200, max: 200 })
end

这可以按预期工作，但是当我想要更改GeoLineString字段内部的坐标时，mongoid不会将字段“coordinates”识别为脏，因此不会在数据库中更新它。例如：

t=Track.last
=> #<Track _id: 568a70e6859c862ee1000000, created_at: 2016-01-04 13:17:40 UTC, updated_at: 2016-01-04 13:17:40 UTC, name: nil, coordinates: {"type"=>"LineString", "coordinates"=>[[1, 2], [2, 2]]}>

t.coordinates.coordinates.push([3,3])

t
=> #<Track _id: 568a70e6859c862ee1000000, created_at: 2016-01-04 13:17:40 UTC, updated_at: 2016-01-04 13:17:40 UTC, name: nil, coordinates: {"type"=>"LineString", "coordinates"=>[[1, 2], [2, 2], [3, 3]]}>

t.changed?
=> false

我怎样才能让mongoid认识到价值已发生变化？

如何处理mongoid自定义类型的脏跟踪？

0 个答案: