将RGeo列反序列化为SphericalPointImpl

Question

在Rails 4.2.4和activerecord-postgis-adapter 3.1.2中有一个带RGeo列的表

class CreateAddresses < ActiveRecord::Migration
  def change
    create_table :addresses do |t|
      t.st_point :coordinates,   geographic: true, srid: 4326
    end

    add_index :addresses, :coordinates, using: :gist
  end
end

以及按位置对对象进行分组的方法

def self.group_by_coords
    includes(:address).
    joins(:address).
    group('addresses.coordinates::geometry').
    pluck(
      'array_agg(realties.id) as ids, addresses.coordinates::geometry'
    )
  end

进行相应的测试：

describe 'group_by_coords' do
  it 'correctly group realties' do
    # create samples
    expect(Realty.group_by_coords).to eq(
      [[[r1.id, r2.id], r1.address.coordinates], [[r3.id], r3.address.coordinates]]
    )
  end
end

问题是pluck返回RGeo::Geos::CAPIPointImpl而不是RGeo::Geographic::SphericalPointImpl

expected: [[[1670, 1671], #<RGeo::Geographic::SphericalPointImpl:0x3fd37e9b8a20 "POINT (106.0 10.0)">], [[1672], #<RGeo::Geographic::SphericalPointImpl:0x3fd37ab2dddc "POINT (106.5 10.5)">]]
got: [[[1671, 1670], #<RGeo::Geos::CAPIPointImpl:0x3fd37a335a44 "POINT (106.0 10.0)">], [[1672], #<RGeo::Geos::CAPIPointImpl:0x3fd37a33560c "POINT (106.5 10.5)">]]

我相信为了确定必须指定一个正确的工厂。我试过了 像这样指定它

RGeo::ActiveRecord::SpatialFactoryStore.instance.tap do |config|
  config.default = RGeo::Geos.factory_generator
  config.register(RGeo::Geographic.spherical_factory(srid: 4326), geo_type: "point", sql_type: "geography")
end

但它会将所有点反序列化为RGeo::Geos::CAPIPointImpl，这更加通用且与现有代码库不兼容。

所以问题是如何将所有点反序列化为RGeo::Geographic::SphericalPointImpl？