MongoDB - set nested field using name from variable

Question

I want to create new field in my document, lets call it "shelf", it will be an object. Next I want to make two $set operations - I want to put arrays named "Tom" and "Anna" into my "shelf".

The problem is that I can't match correct query to do that.

I'm using nodejs MongoDB driver.

var myid = 'Tom-Anna'
var TomArray = ["Tom"]
var AnnaArray = ["Anna"]

await db.collection('people').updateOne(
        { pairid: myid },
        { $set: { shelf: TomArray } },
        { upsert: true }
      )

await db.collection('people').updateOne(
        { pairid: myid },
        { $set: { shelf: AnnaArray } },
        { upsert: true }
      )

Finally, the "shelf" document containing only "AnnaArray", because it's overwriting previously added "TomArray".

I can't add "Tom" and "Anna" array to "shelf" at the same time because content of arrays are generated separately.

I was trying this code:

var name = 'Tom'
var array = ['Tom']
await db.collection('people').updateOne(
        { pairid: myid },
        { $set: { shelf[name]: array } },
        { upsert: true }
      )

But it's throwing following error:

{ $set: { shelf[name]: array } }, ^

SyntaxError: Unexpected token [

My goal is to set my field like JSON:

"shelf": { "Tom": ["Tom"], "Anna": ["Anna"] }

mickl · Accepted Answer · 2019-08-15 05:00:08Z

5

You can use dot notation to specify nested key name:

var name = 'Tom'
var array = ['Tom']
db.people.update({ pairid: 1 }, { $set: { [`shelf.${name}`]: array } })

answered Aug 15, 2019 at 5:00

mickl

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