CODEWITHSUNDEEP
node.jsmongodb
user1434702
user1434702

Reputation: 829

How to update or return a sub document

I have a document like this.

{
    '_id': xxx,
    'name': xxx,
    'background': [],
    'songs': [
        {
            'title': xxx,
            'background': []
        }
    ]
}

First, how could i just return song document not all. I want something like this.

function(err, doc) {
    //the doc is {'title': xxx, 'background': []}
}

Second, how could i push a data in background array that doc is in songs.

collection.update(
    {'_id': xxx, songs: {$elemMatch:{'title': xxx}},
    {
         $push: {'background': xxx}
    }
)

This sample code always push the data to background of root doc not song doc.

Upvotes: 0

Views: 42

Answers (1)

Josh C.
Josh C.

Reputation: 4363

You can limit fields returned from a Mongo query through a projection. This might look like

collection.find( { /*some criteria*/ }, { song: 1, _id:0 } )

To modify an element in an array within a document, you will need to use the positional $ operator

collection.update( {'_id': xxx, songs: {$elemMatch:{'title': xxx}}, { $push: {'songs.$.background': xxx} }, callback )

Upvotes: 1

Related Questions