Empty array response to Get request - mongodb

Question

I am following a full-stack web development guide. The git repository can be found here:
https://github.com/cliveharber/gettingMean-2/tree/chapter-06
In chapter 6, I've created an API that is supposed to display a list of locations based on the GPS coordinates. When I test the get request I get an empty array. The get request URL is:
http://localhost:3000/api/locations?lat=51.455041&lng=-0.9690884
This is the controller code for locations:
Note that I use a Mongoose aggregate called $geonear to find a list of locations close to a specified point
const locationsListByDistance = async (req, res) => {
const lng = parseFloat(req.query.lng);
const lat = parseFloat(req.query.lat);
const near = {
type: "Point",
coordinates: [lng, lat]
};
const geoOptions = {
distanceField: "distance.calculated",
key: 'coords',
spherical: true,
maxDistance: 20000
};
if (!lng || !lat) {
return res
.status(404)
.json({ "message": "lng and lat query parameters are required" });
}
try {
const results = await Loc.aggregate([
{
$geoNear: {
near,
...geoOptions
}
}
]);
const locations = results.map(result => {
return {
id: result._id,
name: result.name,
address: result.address,
rating: result.rating,
facilities: result.facilities,
distance: `${result.distance.calculated.toFixed()}m`
}
});
res
.status(200)
.json(locations);
} catch (err) {
res
.status(404)
.json(err);
}
};
This is my location model:
const locationSchema = new mongoose.Schema({
name: {
type: String,
required: true
},
address: String,
rating: {
type: Number,
'default': 0,
min: 0,
max: 5
},
facilities: [String],
coords: {
type: {type: String},
coordinates: [Number]
},
openingTimes: [openingTimesSchema],
reviews: [reviewSchema]
});
I am sure I use the right GPS coordinates in the get request URL. This the document I am trying to retrieve from the database:
I am not sure why I'm getting an empty array when testing this API. Are there any issues in my code?

Answer 1

If I'm reading your code right, the aggregation that you are sending is:
Loc.aggregate([
{
$geoNear: {
{
type: "Point",
coordinates: [lng, lat]
},
distanceField: "distance.calculated",
key: 'coords',
spherical: true,
maxDistance: 20000
}
}
]);
You haven't mentioned creating a 2dsphere index on the coords field of the collection, I'll assume you have done that.
That aggregation seems to be missing the near field name, like:
Loc.aggregate([
{
$geoNear: {
near: {
type: "Point",
coordinates: [lng, lat]
},
distanceField: "distance.calculated",
key: 'coords',
spherical: true,
maxDistance: 20000
}
}
]);