MongoDB返回集合，但长度属性显示为0

Question

我是express mongo主干的新手。我通过主干收集从mongodb获取数据。fetch（）；作为回报，我得到了数据，但正如你在下面看到的。长度和型号数组显示为0，这是错误的。因为如果我向下钻取，我可以看到我所有的文档/模型。我做错了什么？下面是我在客户端的代码-主干

var API = {
    getContactEntities: function () {
        var contacts = new Entities.ContactCollection();
        console.log("fetching data from database");
        contacts.fetch();
        console.log(contacts);
        if (contacts.length === 0) {
            // if we don't have any contacts yet, create some for convenience
            //return initializeContacts();
        }
        return contacts;
    }
};

下面是我在server-express上的代码。正在响应url“/contacts”上获取的js

//app.get('/contacts', appointments.allContacts);
exports.allContacts = function (req, res) {
    db1.db.users.find({}, function(err, appointments) {
        if (err) { res.json(err); }
        res.json(appointments);
    });
};

--------------------------------------------------------------------------------------
child {length: 0, models: Array[0], _byId: Object, constructor: function, url: "contacts"…}
_byId: Object
c5: child
c6: child
c7: child
c8: child
__proto__: Object
_events: Object
_listenerId: "l4"
length: 4
models: Array[4]
0: child
_changing: false
_events: Object
_pending: false
_previousAttributes: Object
attributes: Object
_id: "52604e58d40340638c5e4b45"
address: Object
firstName: "Alen"
lastLogin: ""
lastName: "Wilkins"
phoneNumber: "555-0184"
pwd: ""
userId: "1"
userName: "[e-mail]"
userStatus: "active"
userType: "admin"
__proto__: Object
changed: Object
cid: "c5"
collection: child
__proto__: Surrogate
1: child
2: child
3: child
length: 4
__proto__: Array[0]
__proto__: Surrogate

你们谁能解释一下出了什么问题？

为了完全排除MongoDB的行为，我只传递了一个json对象作为resonse，但结果仍然是一样的！！！因此，它必须是有明确或主干的东西

res.json(
        [
            { _id: 1, firstName: 'Alice_db', lastName: 'Arten',
                phoneNumber: '555-0184' },
            { _id: 2, firstName: 'Bob_db', lastName: 'Brigham',
                phoneNumber: '555-0163' },
            { _id: 3, firstName: 'Charlie_db', lastName: 'Campbell',
                phoneNumber: '555-0129' }
        ]
    )

非常感谢提前。

比尔，奇丹

Answer 1

你贴的大多数东西看起来都不错。setTimeout您没有抓住要点：

contacts.fetch();
//fetch is asynchronous. contacts is ALWAYS still going to be empty here
console.log(contacts);
contacts.on('sync', function () {
  //look, the 'sync' event has fired meaning the data is actually here now!
  console.log(contacts); 
});