How to update array elements in MongoDB instead of creating new one

Question

I have problem with my code. I want to update document, which looks like this:

    {
"_id": {
    "$oid": "5bf2ad5a0d46b81798232cf9"
},
"manufacturer": "VW",
"model": "Golf ",
"VIN": "WVWZZZ1J212566691",
"doors": 3,
"class": "compact",
"reservations": [
    {
        "_id": {
            "$oid": "5bf2ad5a0d46b81798232cfa"
        },
        "pick_up_date": {
            "$date": "2014-10-13T09:13:00.000Z"
        },
        "drop_off_date": {
            "$date": "2014-10-14T09:13:00.000Z"
        },
        "user_id": {
            "$oid": "5bec00bdfb6fc005dcd5423b"
        }
    }
],
"createdAt": {
    "$date": "2018-11-19T12:32:26.665Z"
},
"updatedAt": {
    "$date": "2018-11-19T12:32:26.665Z"
},
"__v": 0
  }

I want to add new reservation to array Reservations. My function:

const createReservationForCarId = ({ body , params }, res, next) =>
    Carmodel.findById(params.id)
        .then(notFound(res))
        .then((carmodel) => carmodel ? Object.assign(carmodel, body).save() : null)
        .then((carmodel) => carmodel ? carmodel.view(true) : null)
        .then(success(res))
        .catch(next)

But when I'm trying to update through:

router.put('/:id/reservation',
    createReservationForCarId)

Body:

{

    "reservations":[

    {

        "pick_up_date" : "October 13, 2017 11:13:00",  
        "drop_off_date": "October 14, 2017 11:13:00",
        "user_id":"5bec00bdfb6fc005dcd5423b"

    }
    ]
}

Mongo instead of update my old document is creating new one with only one reservation gave in above body.

What should I do to only update existing document, not creating new one?

https://docs.mongodb.com/manual/reference/method/db.collection.update/ — Ferus7, Nov 19 '18 at 14:03

Sunny Parekh · Answer 1 · 2018-11-20T06:46:23.240

2

I suggest you use $push operator of Mongoose which will append your object to the existing array and it will not create a new one.

Check out this link:- https://github.com/Automattic/mongoose/issues/4338

edited Nov 20 '18 at 06:46

answered Nov 20 '18 at 06:38

Sunny Parekh

945
7
17

score 0 · Accepted Answer · answered Nov 19 '18 at 14:43

0

You can try the findAndModify instead of findById in your code. Check out the syntax here

answered Nov 19 '18 at 14:43

Susmita Bhattacharjee

136
1
2
6

I have modified my method and changed **findById()**, to **findByIdAndUpdate()**, but now it modifies existing document, in detail existing array object in Reservations. I want to **add** new object to array, **not modify** existing. https://mongoosejs.com/docs/api.html#model_Model.findByIdAndUpdate How to fix this? @Susmita Bhattacharjee – Matthew Nov 19 '18 at 16:43
You can use **$push** property to append new elements to your reservation array. Take a look at the accepted answer of [this](https://stackoverflow.com/questions/41501939/how-to-update-a-array-value-in-mongoose). In this example, try replacing `{ "$push": { "childrens": employee._id }}` with something like `{ "$push": { "reservations": {"newelement1": "newvalue1", "newelement2":"newvalue2"} }}` – Susmita Bhattacharjee Nov 20 '18 at 06:54

score 0 · Answer 3 · answered Nov 19 '18 at 22:02

I haven't used mongoose but they have documentation for array manipulation.

See here: https://mongoosejs.com/docs/api.html#mongoosearray_MongooseArray-push

Also here is the related mongo doc for array manipulation: https://docs.mongodb.com/manual/reference/operator/update/push/

How to update array elements in MongoDB instead of creating new one

3 Answers3