Node.js: Document returning undefined - Mongoose

问题

Phone.find {number : "12345678"}, (err,phone) ->
            phone.forEach (item, i) ->
                console.log item
                console.log item.subdomain
                console.log item.subdomain_id
                console.log item.city

returns:

{ _id: 4e9b614e01c642c2be000002,
  city: 'San Francisco',
  country: 'US',
  indicative: '234',
  number: '12345678',
  subdomain_id: 4e9b532b01c642bf4a000003 }

undefined
undefined
San Francisco

Why is the item.subdomain_id returning undefined if it's in the document?

Edit:

I added subdomain_id to the Schema and it now works (item.subdomain_id), however, I'm not getting the subdomain document, only the ID. I want to get item.subdomain and be able to call methods on it.

Thanks

回答1:

If you're storing an ObjectID, not embedded documents, you need to use the populate() function to grab the referenced objects:

Phone.find({number : "12345678"}).populate('subdomain_id').run (err, phones) ->
  for phone in phones
    console.log phone

http://mongoosejs.com/docs/populate.html

回答2:

So I was just searching for an answer to the same question. What I was doing was using Mongoose's find (through object inheritance), in order to use a json find query.

What it looked like was this:

User.find({email:req.body.email}).exec(function(err,user){
  console.log(user.email);
}

What I forgot about and hadn't considered is that the return object will be an Array. This is because your find query can easily and often does include multiple objects. Because of this, you will either need to enumerate your results, or if your query is only expected to findOne (and we didn't use findOne), you can simply call object 0 like so:

User.find({email:req.body.email}).exec(function(err,user){
  console.log(user[0].email);
}

I hope this helps, let us know if you are still having trouble.

来源：https://stackoverflow.com/questions/7788013/node-js-document-returning-undefined-mongoose

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