Module: Mongoid::Geospatial::ClassMethods

Defined in:
lib/mongoid/geospatial.rb

Overview

Methods applied to Document's class

Instance Method Summary collapse

Instance Method Details

#geo_near(field_name, coordinates, options = {}) ⇒ Mongo::Collection::View::Aggregation

Performs a $geoNear aggregation pipeline stage to find documents near a point, returning them sorted by distance and including the distance.

This method is a wrapper around the MongoDB $geoNear aggregation stage, which allows for more complex queries and options than the simple near or near_sphere methods.

  • But it's not chainable like a standard Mongoid query *

Example:

# Find places near [10, 20], using spherical calculations, up to 5km away
Place.geo_near(:location, [10, 20],
             spherical: true,
             maxDistance: 5000, # 5 kilometers in meters
             distanceField: 'dist.calculated',
             query: { category: 'restaurant' },
             limit: 10)

# Iterate over results — hashes, not documents
Place.geo_near(:location, [10, 20], spherical: true).each do |doc|
puts "#{doc['name']} is #{doc['distance']} meters away."
end

Parameters:

  • The name of the geospatial field to query. This field must be indexed with a geospatial index (2d or 2dsphere).

  • The point to search near. Examples: [lng, lat], { type: 'Point', coordinates: [lng, lat] }, a Mongoid::Geospatial::Point object.

  • (defaults to: {})

    Options for the $geoNear stage. Key options include:

    • :spherical [Boolean] If true, calculates distances using spherical geometry. Defaults to false.
    • :distanceField [String] Name of the output field that will contain the distance. Defaults to 'distance'.
    • :maxDistance [Numeric] The maximum distance from the center point that documents can be. For spherical queries, specify distance in meters. For 2d queries, in the same units as coordinates.
    • :minDistance [Numeric] The minimum distance. (MongoDB 2.6+)
    • :query [Hash] Limits the results to the documents that match the query.
    • :limit [Integer] The maximum number of documents to return (applied as a separate $limit pipeline stage).
    • :distanceMultiplier [Numeric] A factor to multiply all distances by.
    • :includeLocs [String] Output field naming WHICH location the distance was measured to — the one that matters when the queried field holds several points, or a Polygon. includeLocs: 'matchedPoint' adds a matchedPoint field to each output document.

Returns:

  • The raw pipeline result — it yields BSON::Document hashes, NOT model instances, so read a field with doc['name'] and the distance with doc['distance'] (or whatever :distanceField was set to). Nothing is instantiated: $geoNear adds fields a document does not have, and a Point field comes back as a raw pair. Need models? .map { |attrs| Model.instantiate(attrs) } at the call site.

Raises:

  • If coordinates cannot be mongoized.



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# File 'lib/mongoid/geospatial.rb', line 378

def geo_near(field_name, coordinates, options = {})
  mongoized_coords = Mongoid::Geospatial.mongoize_point!(coordinates)

  # User-provided options. Work with a copy.
  user_options = options.dup
  limit_value = user_options.delete(:limit) # Handled by a separate pipeline stage

  # `km:` is metres on the wire, and metres only holds for a GeoJSON
  # `near` on a sphere. A legacy pair would read `maxDistance` in radians.
  if (km = user_options.delete(:km))
    user_options[:maxDistance] = km.to_f * 1_000
    user_options[:spherical] = true
    mongoized_coords = { 'type' => 'Point', 'coordinates' => mongoized_coords }
  end

  # Core $geoNear parameters derived from method arguments, these are not overrideable by user_options.
  geo_near_core_params = {
    key: field_name.to_s,
    near: mongoized_coords
  }

  # Defaultable $geoNear parameters. User options will override these.
  geo_near_defaultable_params = {
    distanceField: 'distance',
    spherical: false # Default to planar (2d) calculations
  }

  # Merge user options over defaults, then ensure core parameters are set.
  geo_near_stage_options = geo_near_defaultable_params.merge(user_options).merge(geo_near_core_params)

  # $geoNear wants a strict boolean, and honours the caller's choice.
  geo_near_stage_options[:spherical] = geo_near_stage_options[:spherical] ? true : false

  # Note on performance:
  # $geoNear is an aggregation pipeline stage. For simple proximity queries,
  # it might exhibit slightly higher "real" time (wall-clock time) in benchmarks
  # compared to direct query operators like $near or $nearSphere. This is often
  # due to the inherent overhead of the aggregation framework versus a direct query.
  # However, $geoNear offers more capabilities, such as returning the distance
  # (distanceField), distanceMultiplier, includeLocs, and integrating with other
  # aggregation stages, which are not available with $near/$nearSphere.
  pipeline = [{ '$geoNear' => geo_near_stage_options }]

  # Add $limit stage if limit_value was provided
  pipeline << { '$limit' => limit_value.to_i } if limit_value

  collection.aggregate(pipeline)
end

#geom(name = :geom) ⇒ Object

A Point on a 2dsphere index. Default name is geom.



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# File 'lib/mongoid/geospatial.rb', line 160

def geom(name = :geom)
  field name, type: Point, sphere: true
end

#nearby(coordinates, km: nil, field: nil) ⇒ Mongoid::Criteria

Provides a convenient way to find documents near a given set of coordinates. It automatically uses the first spatial field defined in the model and determines whether to use a planar (.near) or spherical (.near_sphere) query based on the field's definition options (spatial: true vs sphere: true).

Example:

Bar.nearby([10, 20])
Alarm.nearby(my_point_object, km: 30)

Parameters:

  • The coordinates (e.g., [lon, lat]) or a Point object to find documents near to.

  • (defaults to: nil)

    Optional cap in kilometres.

Returns:

  • A criteria object for the query.



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# File 'lib/mongoid/geospatial.rb', line 280

def nearby(coordinates, km: nil, field: nil) # rubocop:disable Naming/MethodParameterName
  pin, sphere = spatial_field(field)
  return criteria.where(Mongoid::Geospatial.near_selector(pin, coordinates, km, sphere: sphere)) if km

  criteria.where(pin.send(sphere ? :near_sphere : :near) => coordinates)
end

#nearest(geom, km, field: nil) ⇒ Object

The single closest document within km, or nil.

`within(geom, km).first`   NOT the nearest one
`nearest(geom, km)`        the nearest one

Mongoid's #first and #last sort by _id when the criteria carries no sort of its own (contextual/mongo.rb, view.sort || { _id: 1 }), and that _id sort replaces the distance order $near put there. It reads as working every time the closest document happens to be the oldest.



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# File 'lib/mongoid/geospatial.rb', line 323

def nearest(geom, km, field: nil) # rubocop:disable Naming/MethodParameterName
  within(geom, km, field: field).limit(1).to_a.first
end

#remember_indexed(name) ⇒ Object

One field, one entry, always a Symbol — a field may carry both a 2d and a 2dsphere index, and spatial: true calls this on its way in too.



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# File 'lib/mongoid/geospatial.rb', line 152

def remember_indexed(name)
  sym = name.to_sym
  spatial_fields_indexed << sym unless spatial_fields_indexed.include?(sym)
end

#spatial_field(field = nil) ⇒ Array

The pin .nearby, .within and .nearest read, and whether it is on a sphere. Handed nothing, the first spatial field — a model with two pins (geom :pick_up, geom :drop_up) has to name the one it means.

Returns:

  • [field name as a Symbol, sphere?]



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# File 'lib/mongoid/geospatial.rb', line 294

def spatial_field(field = nil)
  sym = (field || spatial_fields.first)&.to_sym
  unless sym && spatial_fields.include?(sym)
    raise ArgumentError, "#{name} has no spatial field #{sym.inspect} — it has #{spatial_fields.inspect}. " \
                         "Mark one with 'spatial: true' or 'sphere: true'."
  end

  [sym, fields.fetch(sym.to_s).options[:sphere] ? true : false]
end

#spatial_index(name, options = {}) ⇒ Object

Creates a 2d spatial index for the given field.

Parameters:

  • The name of the field to index.

  • (defaults to: {})

    Additional options for the index.



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# File 'lib/mongoid/geospatial.rb', line 131

def spatial_index(name, options = {})
  remember_indexed(name)
  index({ name => '2d' }, options)
end

#spatial_scope(field_name, default_geo_near_options = {}) ⇒ Object

Defines a class method to find the closest document to a given point using the specified spatial field via the geoNear command.

Example:

class Place
include Mongoid::Document
include Mongoid::Geospatial
field :location, type: Array
spherical_index :location # Assumes a 2dsphere index for spherical queries
spatial_scope :location, spherical: true # Default to spherical for this scope
end

Place.closest_to_location([lon, lat]) # Finds the single closest place
Place.closest_to_location([lon, lat], max_distance: 500) # Override/add options

Parameters:

  • The name of the spatial field to query.

  • (defaults to: {})

    Default options for the geoNear command (e.g., { spherical: true, max_distance: 1000 }). The key option will be automatically set to field_name.



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# File 'lib/mongoid/geospatial.rb', line 217

def spatial_scope(field_name, default_geo_near_options = {})
  method_name    = :"closest_to_#{field_name}"
  field_name_sym = field_name.to_sym
  # key_name       = field_name.to_s # Original geoNear used 'key' for field name

  singleton_class.class_eval do
    define_method(method_name) do |coordinates, additional_options = {}|
      # `coordinates` should be [lon, lat] or a GeoJSON Point hash
      # `self` here is the class (e.g., Bar)

      merged_options = default_geo_near_options.merge(additional_options)

      # Determine if spherical based on options or field definition
      is_spherical = if merged_options.key?(:spherical)
                       merged_options[:spherical]
                     else
                       # self.fields uses string keys for field names
                       field_def = fields[field_name.to_s]
                       field_def && field_def.options[:sphere]
                     end
      query_operator = is_spherical ? :near_sphere : :near

      # Prepare the value for the geospatial operator
      # Mongoid::Geospatial::Point.mongoize ensures coordinates are in [lng, lat] array format
      # from various input types (Point object, array, string, hash).
      mongoized_coords = Mongoid::Geospatial::Point.mongoize(coordinates)

      geo_query_value = if merged_options[:max_distance]
                          {
                            # Using $geometry for clarity when $maxDistance is used,
                            # which is standard for $near/$nearSphere operators.
                            '$geometry' => { type: 'Point', coordinates: mongoized_coords },
                            '$maxDistance' => merged_options[:max_distance].to_f
                          }
                        else
                          mongoized_coords # Simple array [lng, lat] for the operator
                        end

      # Start with a base criteria, applying an optional filter query
      current_criteria = merged_options[:query] ? where(merged_options[:query]) : all

      # Apply the geospatial query. $near and $nearSphere queries return sorted results.
      current_criteria.where(field_name_sym.send(query_operator) => geo_query_value)
    end
  end
end

#spherical_index(name, options = {}) ⇒ Object Also known as: sphere_index

Creates a 2dsphere index for the given field, suitable for spherical geometry calculations.

Parameters:

  • The name of the field to index.

  • (defaults to: {})

    Additional options for the index.



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# File 'lib/mongoid/geospatial.rb', line 142

def spherical_index(name, options = {})
  remember_indexed(name)
  index({ name => '2dsphere' }, options)
end

#within(geom, km, field: nil) ⇒ Object

Documents within km of geom, nearest first. Spherical either way: the field's index decides the dialect, see .near_selector.



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# File 'lib/mongoid/geospatial.rb', line 308

def within(geom, km, field: nil) # rubocop:disable Naming/MethodParameterName
  nearby(geom, km: Mongoid::Geospatial.km!(km), field: field)
end