MongoDB，如何使用$ geoNear检索给定范围内的文档

Question

The documents to be retrieved are tutors that have a range (an integer value), corresponding to how far they will to move. And if a customer look for a tutor in 48 rue de Varenne, Paris, for example, we're supposed to retrieve only the tutors that can go to 48 rue de Varenne, Paris ( the distance between the search location and the tutor location must be less than the tutor range )

Would you know how to do that ? The query is a latitude and a longitude (location) and the tutor also has a location (lat and lng) and a range (how far he is able to go).

Here is a simplified version of the tutor model :

import mongoose from 'mongoose';
import validate from 'mongoose-validator';
import { User } from './user';
import mongooseAggregatePaginate from 'mongoose-aggregate-paginate';

var ObjectId = mongoose.Schema.Types.ObjectId;


var tutorSchema = mongoose.Schema({
    location: {
        address_components: [
            {
                long_name: String,
                short_name: String,
                types: String
            }
        ],
        description: String,
        lat: Number,
        lng: Number

    },
    range: {
        type: Number,
        default: 15
    },
    loc: {
        type: { type: String },
        coordinates: []
    }
});

tutorSchema.plugin(mongooseAggregatePaginate);
tutorSchema.index({ "loc": "2dsphere" });
module.exports = {
    Tutor
};

And here is my query so far (without taking into account the range, lon1 and lat1 being the query parameters ) :

 exports.search = (req, res) => {
  let lat1 = req.body.lat;
  let lon1 = req.body.lng;
  let page = req.body.page || 1;
  let perPage = req.body.perPage || 10;
  let radius = req.body.radius || 10000;

  let levelsIn = req.body.levels && req.body.levels.length !== 0 ? req.body.levels.map(level => {
    return ObjectID(level);
  }) : null;
  let subjectsIn = req.body.subjects && req.body.subjects.length !== 0 ? req.body.subjects.map(subject => {
    return ObjectID(subject);
  }) : null;

  var options = { page: page, limit: perPage,  sortBy: { updatedDate: -1 } }

  const isAdmin = req.user ? req.user.role === "admin" || req.user.role === "super-admin" : false;

  let match = {}

  if (levelsIn) match.levels = { $in: levelsIn };
  if (subjectsIn) match.subjects = { $in: subjectsIn }
  if (typeof req.body.activated !== "undefined") match.profileActivated = req.body.activated;
  if (req.body.from) match.createdAt = { $gte: new Date(req.body.from) };
  if (req.body.to) {
    if (match.createdAt) match.createdAt.$lte = new Date(req.body.to);
    else match.createdAt = { $lte: new Date(req.body.to) };
  }

  var aggregate = null;

  if (!isAdmin) {
    match.activated = true
    match.profileActivated = true
    match.profileOnline = true
  }

  if (lat1 && lon1) {

   match.$expr = {
        $lt: ["$distance", "$range"] // "calculated_distance < tutor_range"
     }

       aggregate = Tutor.aggregate([
     {

       "$geoNear": {
         "near": {
           "type": "Point",
           "coordinates": [lon1, lat1]
         },
         "distanceField": "distance", // this calculated distance will be compared in next section
         "distanceMultiplier": 0.001,
         "spherical": true
       }
     },
     {
       $match: match
     }
     ]);
  } else {
    aggregate = Tutor.aggregate([
      {
        $match: match
      }
    ]);
  }

  Tutor
    .aggregatePaginate(aggregate, options, function (err, result, pageCount, count) {
      if (err) {
        return res.status(400).send(err);
      }
      else {

        var opts = [
          { path: 'levels', select: 'name' },
          { path: 'subjects', select: 'name' },
          { path: 'assos', select: 'name' }
        ];
        Tutor
          .populate(result, opts)
          .then(result2 => {
            return res.send({
              page: page,
              perPage: perPage,
              pageCount: pageCount,
              documentCount: count,
              tutors: result2
            });
          })
          .catch(err => {
            return res.status(400).send(err);
          });
      }
    })
};

Thank you for your help !

Answer 1

You just need to add a filter in your pipeline to compare distance and range fields:

{
    $match: {
        $expr: {
            $lt: ["$distance", "$range"] // "calculated_distance < tutor_range"
        }
    }
}

Complete query:

aggregate = Tutor.aggregate([{
        "$geoNear": {
            "near": {
                "type": "Point",
                "coordinates": [lon1, lat1]
            },
            "distanceField": "distance", // this calculated distance will be compared in next section
            "spherical": true
        }
    },
    {
        $match: {
            $expr: {
                $lt: ["$distance", "$range"]
            }
        }
    }
]);