与Mongoose中其他查询字段相结合的elemMatch

Question

[{
    "_id": "529532bee0ea703842000003",
    "patientId": "123",
    "name": {
        "firstName": "John",
        "family": "Smith"
    },
    "diet": [{
        "_id": "1",
        "mealtType": "Break Fast",
        "timeofMeal": "2013-11-12T03:05:06.000Z",
        "status": "I",
        "calorie": {
            "value": 500,
            "unit": "cals"
        }
    },
    {
        "_id": "1",
        "mealtType": "Break Fast",
        "timeofMeal": "2013-11-12T03:05:06.000Z",
        "status": "A",
        "calorie": {
            "value": 550,
            "unit": "cals"
        }
    }]
}]

query.where('patientId', 123)
     .where('diet').elemMatch(function(elem) {
    elem.where('_id', 1)
    elem.where('status', 'A')
})

Mongoose: patients.find({ diet: { '$elemMatch': { _id: '1', status: 'A' } }, patientId: '123' })

我只能通过包装每个where条件{'patient id':'123'}，{'diet':{$elemmatch:{'status':'a'}}}来使它在Mongo shell中工作。

db.patients.find({'patientId':'123'},{'diet' : { $elemMatch : {'status':'A'} }} ).pretty() // works fine 

我如何强制Mongoose将每个查询字段括在花括号中或任何其他想法中？

Answer 1

在有效的查询中，$elemmatch对象不是另一个查询条件，而是find的输出字段选择（即投影）参数。

要在Mongoose中执行同样的操作，您可以执行如下操作：

PatientsModel.find({patientId: '123'}, {diet: {$elemMatch: {'status': 'A'}}}, cb)

或

PatientsModel
    .where('patientId', '123')
    .select({diet: {$elemMatch: {'status': 'A'}})
    .exec(cb);