How do I perform a $geoIntersects query with Mongoid?

Question

I'm using Sinatra and mongoid driver, now I'm trying to perform this query in mongoid, actually I have a geospatial (Polygon) field called 'geometry':

db.states.find({
    geometry: {
        $geoIntersects: {
            $geometry: {
                type: "Point",
                coordinates: [-99.176524, 18.929204]
            }
        }
    }
})

Actually this query works in mongodb shell.

However, I want to find states that intersects with given point (Point-in-polygon) with mongoid or maybe other ruby driver.

Any help would be greatly appreciated.

Thanks.

Answer 1

I was recently searching for this, and after a while I found the following. Maybe someone else will have use for this..

$geoIntersects is now implemented in mongoid 4.0.0.beta1, but not well documented.. I found this in the origin changelog: https://github.com/mongoid/origin/blob/master/CHANGELOG.md#new-features-1

query.geo_spacial(:location.intersects_line => [[ 1, 10 ], [ 2, 10 ]])
query.geo_spacial(:location.intersects_point => [[ 1, 10 ]])
query.geo_spacial(:location.intersects_polygon => [[ 1, 10 ], [ 2, 10 ], [ 1, 10 ]])
query.geo_spacial(:location.within_polygon => [[ 1, 10 ], [ 2, 10 ], [ 1, 10 ]])

and a commit: https://github.com/mongoid/origin/commit/30938fad644f17fe38f62cf90571b78783b900d8

 # Add a $geoIntersects selection. Symbol operators must be used as shown in
 # the examples to expand the criteria.
 #
 # @note The only valid geometry shapes for a $geoIntersects are: :line,
 #   :point, and :polygon.
 # ...
 # @example Add a geo intersect criterion for a point.
 #   query.geo_intersects(:location.point => [[ 1, 10 ]])

In my project i have mongoid (4.0.0.beta1) and origin (2.1.0) I have a model Polygon

class Polygon
  include Mongoid::Document
  # some fields 

  embeds_many :loc

  # coordinates is an array of two points: [10, 12]
  def find_polygons_with_point(coordinates)
    # This is where the magic happens!
    Polygon.all.geo_spacial(:loc.intersects_point => coordinates)
  end

end

And a model Loc

class Loc
  field :type, type: String #Need to be set to 'Polygon' when creating a new location.
  field :coordinates, type: Array
  # For some reason the array has to be in the format
  # [ [ [1,1], [2,3], [5,3], [1,1] ] ]
  # And the first coordinate needs to be the same as the last
  # to close the polygon

  embedded_in :polygon

  index({ coordinates: "2d" }, { min: -200, max: 200 }) #may not need min/max
end

This code returns all polygons that has this point inside.

There might be more elegant ways of doing this. If so I would like to hear it :)