update nested object in array Mongoose

Question

I would like the nested object with the id 5f0e14241f5ccb42d8742767 to be updated:

 {
        "_id": "5f0b33ab52a4e966c754d963",
        "make": "Toyota",
        "model": "Prius",
        "engine": "1.8",
        "insurances": [
            {
                "yearlyPremium": {
                    "$numberDecimal": "60.39"
                },
                "_id": "5f0e14241f5ccb42d8742767",
                "startDate": "1970-01-19T09:31:15.550Z",
                "monthlyPremium": {
                    "$numberDecimal": "5.49"
                },
                "excess": 100
            },
            {
                "yearlyPremium": {
                    "$numberDecimal": "71.39"
                },
                "_id": "5f0e147c0340243eb03b5247",
                "startDate": "1970-01-19T09:31:15.550Z",
                "monthlyPremium": {
                    "$numberDecimal": "6.49"
                },
                "excess": 100
            },
       ]
 }

So in my PATCH rest api request, I just want to change the monthly premium, from what it is currently 5.49 to 1.50 . Hence I pass the carId: 5f0b33ab52a4e966c754d963 and the particular inusranceId: 5f0e14241f5ccb42d8742767 (nested in Car object) as query params, to identify which insurance in the insurances array needs updating. Then in the request body I pass the item to be modified ( monthlyPremium ):

I followed the stack overflow solution: mongoDB: Update nested array object

So this is what I tried:

router.route('/insurance')
.patch(async (req, res) => {
    const { carId, insuranceId } = req.query
    const { startDate, monthlyPremium, excess } = req.body
    try {
        const foundCar = await Car.findById(carId)
        const foundCar = foundCar.insurances.filter(ins => {
            return ins._id == insuranceId
        })
        
        foundInsurance.startDate = startDate && new Date(startDate * 1000) || foundInsurance.startDate,
        foundInsurance.monthlyPremium = monthlyPremium && parseFloat(monthlyPremium) || foundInsurance.monthlyPremium,
        foundInsurance.yearlyPremium = monthlyPremium && parseFloat(monthlyPremium) * 12 || foundInsurance.yearlyPremium,
        foundInsurance.excess = excess && Number(excess) || foundInsurance.excess
        
        Car.update(
            {_id: carId, "insurances._id": insuranceId}, 
            {$set: {"insurances.$":foundInsurance}}
        )

        res.send(`Insurance updated`)
    } catch (err) {
        res.status(400).json({ error: err })
    }
})

The request queries are captured correctly in the code. The request succeeds and returns Insurance updated , but nothing gets updated. Everything is working except the update method is not updating the info monthlyPremium to 1.50 .

UPDATE

@Mahan, I tried your suggested approach, unfortunately the record still hasn't changed. Printing foundInsurance I get this (it doesn't print the values in the console, just the meta data):

found insurance: {
  yearlyPremium: Decimal128 {
    _bsontype: 'Decimal128',
    bytes: <Buffer 97 17 00 00 00 00 00 00 00 00 00 00 00 00 3c 30>
  },
  _id: 5f0e14241f5ccb42d8742767,
  startDate: 1970-01-19T09:31:15.550Z,
  monthlyPremium: Decimal128 {
    _bsontype: 'Decimal128',
    bytes: <Buffer 25 02 00 00 00 00 00 00 00 00 00 00 00 00 3c 30>
  },
  excess: 100
}

Answer 1

Please try using mongoose arrayFilters like this:

Car.update(
  { _id: carId }, 
  { $set: { "insurances.$[elem]": foundInsurance } },
  { arrayFilters: [ { 'elem._id': insuranceId } ] }
)