geonear

works with geojson data.
performs geoqueries in a pipeline.
must be the first stage in the pipe.
can be used on sharded collections. $near, another find operation, cannot.
When using 2dSperes, the distance is returned in meters.
When using "legacy coordinates" instead of a 2d sphere, the distance is returned in radians.

analysis of geonear args

required args

• near: point searching near
  • {type: "Point", coordinates: [-28.9346438, 51.2345]}
  • a point to search near
• distanceField:
  • field will be INSERTED into returned docs
  • returning the distance from the near fal
• spherical:
  • true if index is a 2d sphere index

optional fields

minDistance maxDistance query includeLocs limit num distanceMultiplier

example

let mongoHQCoords = [-73.98769766092299, 40.757345233626594];
let nearMongoHQ = {
  type: 'Point',
  coordinates: mongoHQCoords,
};

db.nycFacilities.aggregate([
  {
    $geoNear: {
      near: nearMongoHQ,
      distanceField: 'distanceFromMongoDB',
      spherical: true,
    },
  },
]);

adding some restrictions, find 5 nearest hospitals:

• minDistance:
  • closest result desired
• maxDistance:
  • furthest distance desired
• query
  • like $match
• includeLocs:
  • show what location was returned where multiple locations are in a doc
• distanceMultiplier:
  • can convert distance from radians to something else

Find the 5-nearest hospitals to the MongoDB Headquarters, which is defined by the coordinates

let mongoHQCoords = [-73.98769766092299, 40.757345233626594];
let nearMongoHQ = {
  type: 'Point',
  coordinates: mongoHQCoords,
};

db.nycFacilities.aggregate([
  {
    $geoNear: {
      near: nearMongoHQ,
      distanceField: 'distanceFromMongoDB',
      spherical: true,
      query: { type: 'Hospital' },
    },
  },
  {
    $limit: 5,
  },
]);