node-mongodb-native how to create index on sub document?

Question

From the mongodb doc:

http://mongodb.github.io/node-mongodb-native/api-generated/collection.html?highlight=ensureIndex#ensureIndex

Basically create an index for a sub document consists in write something like "address.city" So far I couldn't do the same.

I tried:

index = "category.code";
index = { "category.code": 1 };
index = { "category": {code: 1} };

collection.ensureIndex( index, {unique: true, w: 1}, function(error, data){
        console.log(error ? error : documentName + ': [ensureIndex] ' + JSON.stringify(data));
    });

But no index created.

Is there any other solution? When I do it from the command line via mongo it works.

db.type.ensureIndex({'category.code':1})

But when I run it from a JS script, it doesn't.

var mongodb = require('mongodb');

exports.up = function(db, next){
    var documentName = 'type';
    var collection = mongodb.Collection(db, documentName);
    ...

I'm using https://npmjs.org/package/mongo-migrate module.

Answer 1

This code works as expected in NodeJS:

var MongoClient = require('mongodb').MongoClient;

MongoClient.connect("mongodb://localhost:27017/test", function (err, db) {
    db.collection("test").ensureIndex({ "category.code": 1 }, 
        function(err, result) {        
            db.close();
    });
});

Displaying the indexes for the collection:

Before running code

> use test
switched to db test
> db.test.getIndexes()
[
    {
            "v" : 1,
            "key" : {
                    "_id" : 1
            },
            "ns" : "test.test",
            "name" : "_id_"
    }
]

After running code

> db.test.getIndexes()
[
    {
            "v" : 1,
            "key" : {
                    "_id" : 1
            },
            "ns" : "test.test",
            "name" : "_id_"
    },
    {
            "v" : 1,
            "key" : {
                    "category.code" : 1
            },
            "ns" : "test.test",
            "name" : "category.code_1"
    }
]