Mongoose populate within an object? - node.js

Question

I'm not sure how to populate the sample schema below or if it is even possible. Can a reference be within an object like below? If you can, how would you populate it? E.g. .populate('map_data.location');?
var sampleSchema = new Schema({
name: String,
map_data: [{
location: {type: Schema.Types.ObjectId, ref: 'location'},
count: Number
}]
});
Or will I have to have two separate arrays for location and count like so:
// Locations and counts should act as one object. They should
// Be synced together perfectly. E.g. locations[i] correlates to counts[i]
locations: [{ type: Schema.Types.ObjectId, ref: 'location'}],
counts: [Number]
I feel like the first solution would be the best, but I'm not entirely sure how to get it working within Mongoose.
Thank you very much for any help!

Answer 1

The first solution is possible.
Mongoose currently has limitations (see this ticket here) populating multiple levels of embedded documents, however is very good at understanding nested paths within a single document - what you're after in this case.
Example syntax would be:
YourSchema.find().populate('map_data.location').exec(...)
Other features, such as specifying getters / setters on paths, orderBy and where clauses, etc. also accept a nested paths, like this example from the docs:
personSchema.virtual('name.full').get(function () {
return this.name.first + ' ' + this.name.last;
});
Internally Mongoose splits the string at the dots and sorts everything out for you.

Answer 2

First option is ok, but if someone would have problems with that query map_data.location - Mongoose returns empty array instead of object - I found that this will work:
.populate({
path: 'map_data.location',
model: 'Location'
})

Answer 3

YourSchema.find()
.populate({
path: 'map_data',
populate: {
path: 'location'
}
}).exec(...)
The above statement will populate array of map_data and also the location object of each map_data.
hope this helps someone.

Answer 4

i think you will need this:
if you schema is this:
var sampleSchema = new Schema({
name: String,
map_data: [{
location: {type: Schema.Types.ObjectId, ref: 'location'},
count: Number
}]
});
you monggosse query have to be:
const responseMap=await YourSchema.find()
.populate(
path: 'map_data._id',
model: 'location'
select:['nameLocation','geoPoints','count'],
).exec();
console.log(responseMap);
but you count variable have to be in location schema, and map_data have to containt only id location.

Answer 5

If someone couldn't solve his/her problem I got a solution It works for me.
My Schema:
const categorySchema = new Schema(
{
name: {
type: String,
unique: true
},
products: [{
type: Schema.Types.ObjectId,
ref: 'Product'
}]
})
And then to get a category with an specific name and with their products:
.get('/:name', async (req, res) => {
const { name } = req.params;
const responseMap = await Category.find({name})
.populate({
path: 'products',
model: 'Product',
})
.exec();
res.send(responseMap);})

Answer 6

The first option is the best. "count" is part of object "map_data".