node.js, mongoose how to find in array of objects by multiple IDs

Question

I am using Node.js with Mongoose module and ran in to a problem.

I have a Schema mockup which looks like this:

_id: '',
foo: '',
bar: '',
fb: [{
    id: ''
}]

How do I find all objects in collection for matching fb[0].id plus passing in an array of IDs?

I have tried this (find() method with following query):

{'fb[0].id': {$in: friendsIDList}}

And this:

{'fb': {$in: [{id: friendsIDList}]} }

And even this

{'fb': {$in: {$in: friendsIDList}}}

To be more clear, I have an users object which contains their FB data in fb param, but it is an array containing just one object with data. Now I receive a friend IDs list and want to query all of the user friends.

José F. Romaniello · Accepted Answer · 2014-02-12 12:33:18Z

3

MongoDB has something called dot notation so you can query with 'foo.0.id': 'id' .

Tested as follows:

> db.users.insert({foo: 'foo', bar: 'bar', fb: [ { id: '456' } ]})
> db.users.find({'fb.0.id': '456'}).pretty()
{
    "_id" : ObjectId("52fb695e403fb143985459dc"),
    "foo" : "foo",
    "bar" : "bar",
    "fb" : [
        {
            "id" : "456"
        }
    ]
}

answered Feb 12, 2014 at 12:33

José F. Romaniello

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2 Comments

SharpCoder Over a year ago

what is the significance of 0 in fb.0.id ?

José F. Romaniello Over a year ago

The id property of the first object in the array of the fb property. Like doing fb[0].id = 456 in most programming languages

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