elemMatch与Mongoose中的其他查询字段组合 [英] elemMatch combined with other query fields in Mongoose

问题描述

样本数据:

[{
    "_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"
        }
    }]
}]

我想使用节点中的猫鼬为给定的PatientId('123')仅获取活动的(状态为'A')嵌入式文档(饮食文档).

I wanted to fetch only active (status 'A') embedded document (diet document) for a given patientId ('123') using mongoose in node.

这是我的猫鼬查询:

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

下面的查询生成了猫鼬，该查询为患者带来了嵌入式阵列饮食中的所有元素.

Mongoose generated below query, which is brining all elements from embedded array diet for patient.

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

上面的查询也会获取所有子文档，而与Mongo Shell的状态无关.

The above query fetches all sub documents irrespective of status at Mongo Shell too.

它们唯一的方式是通过包装条件{'patientId':'123'}，{'diet':{$ elemMatch:{'status':'A'}}}来使它在Mongo shell上起作用.

They only way I could make it work at Mongo shell by wrapping each where condition {'patientId':'123'},{'diet' : { $elemMatch : {'status':'A'} }}.

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

如何强制猫鼬将每个查询字段括在花括号或其他任何想法中?

How can I force Mongoose to enclose each query field in a curly braces or any other thoughts?

推荐答案

在可行的查询中，$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.

In your query that works, the $elemMatch object is not another query condition, but is the output field selection (i.e. projection) parameter to find.

要在Mongoose中执行相同的操作，您需要执行以下操作:

To do the same in Mongoose, you'd do something like:

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

OR

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

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