Querying array sub-document in mongoose

Question

I'm using MongoDB in a Node.js app with mongoose. I have a collection in my DB, that can be described with the following schema:

{
  id: String,
  name: String,
  indicators: [{
    date: Date,
    value: Number
  }]
}

where id is unique, and each document has a lot of indicators in it.

I want to able to query the collection according to attributes of the indicators array. For example: sort the array by date or limit the amount of results in the array (possibly with an offset).

How can I do that?

Steve Sanders · Accepted Answer · 2017-07-27 15:44:40Z

1

You can limit the number of items in the array with $slice. For example:

Model.find({}, { indicators: { $slice: 5 } }, function(err, data) {
    // ...
});

Will return the first 5 elements.

But if you want to sort it, then you will have to use the aggregation framework:

Model.aggregate([
    { $unwind: '$indicators' },
    { $sort: { 'indicators.date': -1 } }
], function(err, data) { /* .... */ });

edited Jul 27, 2017 at 15:44

Steve Sanders

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answered Mar 15, 2015 at 17:40

victorkt

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