Geonear and more than one 2dsphere indexes - mongodb

Question

I have a question about use of $near vs geonear in returning distance from stored points in database from the user entered point of interest, if more than one 2dsphere index is present in the schema storing the points.
The use case is below.
In my schema I have a source and a destination location as below. The query using Intracity.find works properly and gives me sorted entries from an entered point of interest.
var baseShippingSchema = new mongoose.Schema({
startDate : Date,
endDate : Date,
locSource: {
type: [Number],
index: '2dsphere'
},
locDest: {
type: [Number],
index: '2dsphere'
}
});
var search_begin = moment(request.body.startDate0, "DD-MM-YYYY").toDate();
var search_end = moment(request.body.endDate1, "DD-MM-YYYY").toDate();
var radius = 7000;
Intracity.find({
locSource: {
$near:{$geometry: {type: "Point",
coordinates: [request.body.lng0,request.body.lat0]},
$minDistance: 0,
$maxDistance: radius
}
}).where('startDate').gte(search_begin)
.where('endDate').lte(search_end)
.limit(limit).exec(function(err, results)
{
response.render('test.html', {results : results, error: error});
}
However, I also want to return the "distance" of the stored points from the point of interest, which as per my knowledge and findings, is not possible using $near but is possible using geonear api.
However, the documentation of geonear says the following.
geoNear requires a geospatial index. However, the geoNear command requires that a collection have at most only one 2d index and/or only one 2dsphere.
Since in my schema I have two 2dspehere indexes the following geonear api fails with the error "more than one 2d index, not sure which to run geoNear on"
var point = { name: 'locSource', type : "Point",
coordinates : [request.body.lng0 , request.body.lat0] };
Intracity.geoNear(point, { limit: 10, spherical: true, maxDistance:radius, startDate:{ $gte: search_begin}, endDate:{ $lte:search_end}}, function(err, results, stats) {
if (err){return done(err);}
response.render('test.html', {results : results, error: error});
});
So my question is how can I also get the distance for each of these stored points, from entered point of interest using the schema described above.
Any help would be really great, as my Internet search is not going anywhere.
Thank you
Mrunal

Answer 1

As you noted the mongodb docs state that
The geoNear command and the $geoNear pipeline stage require that a collection have at most only one 2dsphere index and/or only one 2d index
On the other hand calculating distances inside mongo is only possible with the aggregation framework as it is a specialized projection. If you do not want to take option
relational DB approach: maintaining a separate distance table between all items
then your other option is to
document store approach: calculate distances in your server side JS code. You would have to cover memory limits by paginating results.