Mongoose returning Object not Array

Question

I've struggling trying to make my mongoose query return an array, since I need to:

Find 0..N docs from one collection;
Save this found array in another nested doc collection;

My code:

CarIndex.find({ '_id': { $in: ids } }, 'carID carBrand carModel location')
            .then(collections => {
                const out = []

                collections.map( (doc) => {
                    const {carID ,carBrand ,carModel ,location} = doc
                    const car = {carID ,carBrand ,carModel ,location};
                    out.push(car)
                })

                console.log(out)
                console.log(out.length)
                console.log(typeof out)

                return CarCollection.findOneAndUpdate({ '_id': collectionId }, { $addToSet: { carCollection: { $each: { out } } } })
            });

The output error:

[04/01/2018 11:04:48.980] [LOG]

[ { carID: 'd82e41b0-f14f-11e7-b845-990cb852c2b3',
    carBrand: 'Peugeot',
    carModel: '207 Sed. Passion XR Sport 1.4 Flex 8V 4p',
    location: [-23.539727799999998,-46.5111749] },
  { carID: 'd82f2c10-f14f-11e7-b845-990cb852c2b3',
    carBrand: 'Nissan',
    carModel: 'Sentra 2.0/ 2.0 Flex Fuel 16V Mec.',
    location: [-23.607240972099525,-46.72912079051677] } ]

[04/01/2018 11:04:48.982] [LOG] 2

[04/01/2018 11:04:48.983] [LOG] object

[04/01/2018 11:04:48.997] [ERROR] MongoError: The argument to $each in $addToSet must be an array but it was of type object

But here console.log(out) is an array so what is the issue — Manjeet Singh
– Manjeet Singh, Commented Jan 4, 2018 at 13:17
Actually it is not, if you check the 3rd log, it shows object, leading to the error! Thanks — Leonardo
– Leonardo, Commented Jan 4, 2018 at 13:21
in javascript everything is Object array is also Object. you can check like this out instanceof Array — Manjeet Singh
– Manjeet Singh, Commented Jan 4, 2018 at 13:23
Hmm good catch, but why can't I save it using the $addToSet? — Leonardo
– Leonardo, Commented Jan 4, 2018 at 13:26

Manjeet Singh · Accepted Answer · 2018-01-04 13:28:22Z

1

you can do like this

 CarIndex.find({ '_id': { $in: ids } }, 'carID carBrand carModel location')
                .then(collections => {
                    const out = []

                    collections.map( (doc) => {
                        const {carID ,carBrand ,carModel ,location} = doc
                        const car = {carID ,carBrand ,carModel ,location};
                        out.push(car)
                    })

                    console.log(out)
                    console.log(out.length)
                    console.log(typeof out)

                    return CarCollection.findOneAndUpdate({ '_id': collectionId }, { $addToSet: { carCollection: { $each: out  } } })
                });

answered Jan 4, 2018 at 13:28

Manjeet Singh

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