javascript - 如何在mongodb中查找数组中的元素？

Question

我正在尝试查找数组中具有特定元素的对象:

所以我的查询如下:

router.get('/', function(req, res) {
    var userSubscribed = req.user.email;
    db.posts.find({ "SubscriberList": { $elemMatch: userSubscribed}}, function(err, object){
        if (err) console.log(err);
        else console.log(object);
        res.render('index', { title: 'Home', user: req.user});
    })
});

正在排查的错误如下:

{ [MongoError: Can't canonicalize query: BadValue $elemMatch needs an Object] name: 'MongoError'}

我的数据库中的对象示例:

{ 
    "_id" : ObjectId("5490afa8416841105626cc41"), 
    "post" : { 
        "title" : "Ralph", 
        "category" : "Node", 
        "date" : "2014-12-11", 
        "description" : "Node coming soon!" 
    }, 
    "owner" : "bousamra.ralph@gmail.com", 
    "status" : "active", 
    "category" : "Node", 
    "SubscriberList" : ["alaric@hotmail.com" ]
}

Answer 1

一般来说，在匹配单个数组元素的多个属性时，只需要使用$elemMatch即可。

使用 SubscriberList 只是一个字符串数组，您可以简单地执行以下操作:

router.get('/', function(req, res) {
    var userSubscribed = req.user.email;
    db.posts.find({ "SubscriberList": userSubscribed }, function(err, object){
        if (err) console.log(err);
        else console.log(object);
        res.render('index', { title: 'Home', user: req.user});
    })
});