当我尝试引用其他模式的对象时，为什么猫鼬引用对我不起作用？

Question

I'm trying to access the attributes of an address of a store, but I keep on getting 'undefined'. Turns out that address is only an id, even though I declared a 'ref' in the address's schema. What am I doing wrong here?

Output from initStores

{ name: 'Wegmans',
  address: 53b998d9fcf740e07a4d03f7,
  _id: 53b998d9fcf740e07a4d03f8,
  items: [] }
53b998d9fcf740e07a4d03f7
undefined

routers/index.js

router.post('/initStores', function(req, res) {
    var address = new Address({
        street:     '650 Hylan Dr',
        city:       'Rochester',
        state:      'NY',
        zipcode:    '14623',
        telephone:  '123-456-7890'
    });
    // address.save();

    var store = new Store({
        name:   'Wegmans',
        address: address
    });

    console.log( store );
    console.log( store.address );
    console.log( store.address.street );
    // store.save();
}

models/address.js

var mongoose = require('mongoose'),
    Schema   = mongoose.Schema;

var AddressSchema = new Schema({
    type:      { type: String, default: 'Store' }, // Store, apartment, house, headquarter
    street:    { type: String, require: true }, 
    city:      { type: String, require: true },
    state:     { type: String, require: true },
    zipcode:   { type: String, require: true },
    country:   { type: String, default: 'United States' },
    telephone: { type: String, default: '555-555-5555' }
});

mongoose.model('Address', AddressSchema);

models/store.js

var mongoose = require('mongoose'),
    Schema   = mongoose.Schema,
    ObjectId = Schema.ObjectId;

var StoreSchema = new Schema({
    name:       { type: String, require: true },
    address:    { type: ObjectId, ref: 'Address' },
    items:      [ { type: ObjectId, ref: 'Item' } ]
});

mongoose.model( 'Store', StoreSchema );

Answer 1

For a referenced schema this code works absolutely as designed. Fields in the "Address" schema are not part of the the "Store" schema at all. What the referenced design does here is just stores the _id value of the related document, where the rest of that document will reside in it's own collection.

So, in fact you are actually creating these separately and only ever after a .populate() operation do the different documents actually "appear" to be "joined", just as they would appear in a native way if the document was in fact "embedded".

Store.findById(store._id).populate("address").exec(err,newstore) {

    console.log(newstore);
});

Or since you really have the "store" object already and making sure "saves" have completed:

async.series(
  [
    function(callback) {
      address.save(function(err,address) {
        callback();
      });
    },
    function(callback) {
      store.save(function(err,store) {
        Store.populate(store,{ path: "address"},function(err,store) {
          console.log(store);
          callback();
        });
      });
    }
  ]
);

The only ways in which this can and "should" appear as a whole object without the .populate() which needs the data to be saved, is either by embedding the address so it is part of the "Store", and not saved to a different model and collection:

var StoreSchema = new Schema({
    name:       { type: String, require: true },
    address:    { 
        "type":    { type: String, default: 'Store' }, // Store, apartment, house, headquarter
        street:    { type: String, require: true }, 
        city:      { type: String, require: true },
        state:     { type: String, require: true },
        zipcode:   { type: String, require: true },
        country:   { type: String, default: 'United States' },
        telephone: { type: String, default: '555-555-5555' }
    },
    items:      [ { type: ObjectId, ref: 'Item' } ]
});

Or if your purposes are just purely logging on creation then you can convert and manipulate with .toObject() :

var raw = store.toObject();
raw.address = address.toObject();

console.log( raw );

But otherwise with a referenced model, the intention is that the data is not part of the same object until a .populate() is called.