Can't query mongoDB with mongoose in node.js

Question

Can't query mongoDB with mongoose in node.js

Suppose I have a collection in my mongoDB: db.co and only have one document:

{ "_id" : ObjectId("50d083e32cdcf7ce065b616c"), 
  "age" : 22, 
  "friends" : [ "Tom"], 
  "location" : "NY", 
  "name" : "lee", 
  "skill" : [ "javascript", "java" ] 
 }

Then I want query it in node.js with mongoose through this code:

var coSchema = mongoose.Schema( {
    age: Number,
    friends: Array, 
    location: String,
    name: String,
    skill: Array
})

var Co = mongoose.model('Co', coSchema);
function findSomeoneInCo (name) {
  Co.find({"name": name}, function (err, doc) {
    if (err) {
        console.log('find some one failed: ' + err);
        return;
    }
    console.log('find successed: ' + doc);
  })
}

findSomeoneInCo("lee");

But it return me nothing

What's problem with my code? How can I get the corrent query result?

node.js
mongodb
mongoose

Answer 1

Mongoose pluralizes the lower-cased model name when determining the collection name to use. So with a model name of 'Co' it's going to be looking in the cos collection by default.

To override the default and align with your existing co collection:

var Co = mongoose.model('Co', coSchema, 'co');

Answer 2

Mongoose pluralizes your model name during any CURD operation, Use this & check :

var Co = mongoose.model('Co', coSchema, 'co'); //Even the case matters

or

var coSchema = new Schema({
    age: Number,
    friends: Array, 
    location: String,
    name: String,
    skill: Array
}, {collection:'co'});
var Co = mongoose.model('Co',coSchema);

Answer 3

.find() works asynchronous, meaning that its callback runs when your function already has.

see variable scope in asynchronous function

//try passing a callback function to your search function, like:
function findSomeoneInCo (name, callback) {

  //happens now - here you could still return something

  Co.find({"name": name}, function (err, doc) {

   //happens later - too late to return stuff, function has ran already

    if (err) {
        callback(err);
        return;
    }
    callback(doc);
  })
}


//call your function passing a callback function
findSomeoneInCo("lee", function(doc){
  console.log('do something with your results: ' + doc);
});

Answer 4

I notice your callback to find() has the following parameters : err, doc

find() always returns an array so you really want this to be : err, docs

OR use findOne()

The async stuff shouldn't be a problem in the code you've posted, the nested callbacks will still be executed. Are you sure your connection is OK. I would run an open query :

Co.find({}, function(err, docs){
 console.log(docs);
}

Just to check the collection has something in it