Membuat kueri dengan gabungan &filter di Mongoose

Anda hampir sampai, Anda hanya membutuhkan $match kueri yang berikut:

ubBike.aggregate([
    { "$match": { "cust": req.query._id } },
    {
        "$lookup": {
            "from": "appos",
            "localField": "_id",
            "foreignField": "bike",
            "as": "appointments"
        }
    },
    { "$match": { "appointments.status": { "$ne": "Booked" } } }
]).exec(function(err, bikes){
    if(err) throw err;
    res.send(bikes);    
});