Mongoose - Count subdocuments

Question

Mongoose - Count subdocuments

I need to count subdocuments of the main document. Just an example of scheme:

Model:

{
    title: {type: String, required: true},
    content: {type: String, required: true},
    comments: [{
        comment: {type: String, required: true},
        author: {type: String, required: true}
    }]
}

This query doesn't work:

Model.findById(ObjectId).count('comments', function(err, res) { 
    if (err) { throw err; } 
    else { console.log(res); } 
});

How can I count comments in some document?

node.js
mongoose

Answer 1

You can do this with .length

Model.findById(ObjectId, function(err, res) {
    if (err) { throw err; }
    if (!res) { console.log('model not found'); }
    console.log(res.comments.length);
};