MongoDB push to array with predefined index - mongodb

Question

How do I add an item to Mongoose, if I want to push it to an item of the array?
I want to push it to the document with predefined _id, to the 'productList' array with predefined 'id', to the 'items' array.
{
"_id" : ObjectId("5ba94316a48a4c828788bcc9"),
"productList" : [
{
"id" : 1,
"items" : [
{
"id" : 1,
"name" : "FLOSS 500",
}
]
}
]
}
I thought that it should be something like this, but it did not work:
Products.findOneAndUpdate({_id: req.body._id, productList: {id: req.body.id}}, {$push: {'items': req.body.product}})

Answer 1

You can try this with positional operator $. For search by nested array property use dot-separated syntax:
Products.findOneAndUpdate({
_id: req.body._id,
'productList.id': req.body.id
}, { $push: { 'productList.$.items': req.body.product } });
Full example:
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const Products = mongoose.model('Test', new Schema({
productList: []
}));
mongoose.connect("mongodb://localhost:27017/myapp");
let item = new Products({
"_id": mongoose.Types.ObjectId("5ba94316a48a4c828788bcc9"),
"productList": [
{
"id": 1,
"items": [
{
"id": 1,
"name": "FLOSS 500",
}
]
}
]
});
Products.deleteMany({}).then(() => {
return Products.create(item);
}).then(() => {
return Products.findOneAndUpdate({
_id: mongoose.Types.ObjectId("5ba94316a48a4c828788bcc9"),
'productList.id': 1
}, {
$push: {
'productList.$.items': {
"id": 2,
"name": "FLOSS 600",
}
}
});
}).then(() => {
return Products.find({
_id: mongoose.Types.ObjectId("5ba94316a48a4c828788bcc9"),
'productList.id': 1
});
}).then(data => {
console.log(data);
if (data) {
console.log(data[0].productList);
/* [{"id":1,"items":[{"id":1,"name":"FLOSS 500"},{"id":2,"name":"FLOSS 600"}]}] */
}
}).catch(err => {
console.error(err);
});