MongoDB query nested array knowing parent id element (JavaScript)

Question

If I have a MongoDB collection that looks like this:

_id: ObjectId(" <a objectid> ")
id: " <a userid> "
__v: 0
subscribedTo: Object

With or without Mongoose, how can I query the first child of object subscribedTo, which is called infl and it's an array?

what I'm trying is this, but it says "infl" is undefined:

const foundUser = await Sub.findOne ({ "id" : userId });
console.log("this "+JSON.stringify(foundUser.subscribedTo.infl))

Although when I console log only foundUser.subscribedTo it correctly logs:

this [{"infl":["item1","item2"],"inflId":["item1id","item2id"]}]

What is .subscribedTo.infl ? What do you get if you only console log foundUser ? — ZombieChowder
– ZombieChowder, Commented Dec 13, 2020 at 15:17
infl is an array, first child of subscribedTo which is an object. If i console log JSON.stringify(foundUser) i get the whole json i shown at the top: this {"_id":" xxx","id":" xxx ","__v":0,"subscribedTo":[{"infl":["item1","item2"],"inflId":["item1id","item2id"]}],"updatedAt":"2020-12-13T14:39:53.018Z"} — m4tt
– m4tt, Commented Dec 13, 2020 at 16:07

EraBoss · Accepted Answer · 2020-12-13 18:38:21Z

1

According to your code output, subscribedTo is not an object,

it's an array of objects. So, what you need is :

subscribedTo[0].infl

This will solve your issue for this case.

answered Dec 13, 2020 at 18:38

EraBoss

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