Node.js, mongodb and filtered queries - node.js

Question

I'm using the native API of mongodb and I'm trying to query the data on my collection.
This is my filter object:
{
email: 'admin#email.it',
login: { '$exists': true }
}
and this is one document that it should find:
{
"_id": "5829cd89a48a7813f0cc7429",
"timestamp": "2016-11-14T14:43:18.705Z",
"login": {
"clientIPaddr": "::1",
"clientProxy": "none"
},
"userData": {
"sessdata": {
"sessionID": "CRTZaqpaUs-ep0J6rvYMBlQTdDakGwle",
"email": "admin#email.it",
"token": "3PlfQBVBoftlIpl-FizeCW5TbYMgcYTl4ZPTkHMVyxqv-TldWb_6U3eusJ27gtI64v7EqjT-KPlUUwkJK7hPnQ"
}
}
}
But the query doesn't return anything! Why?

Answer 1

It doesn't return anything because the email field is in an embedded document within the userData field, hence it tries to look for an email field at a higher level within the document that does not exist.
To make this work, you need to modify the filter or create a new query object which includes the embedded field, albeit the key will be in dot notation field i.e. the query should resemble
{
"userData.sessdata.email": "admin#email.it",
"login": { "$exists": true }
}
You can use the bracket notation to create the required field. For example:
var filter = {
email: 'admin#email.it',
login: { '$exists': true }
},
query = {};
Object.keys(filter).forEach(function(key){
if (key === "email") {
query["userData.sessdata."+key] = filter[key];
} else {
query[key] = filter[key];
}
});
console.log(JSON.stringify(query, null, 4));
Output
{
"userData.sessdata.email": "admin#email.it",
"login": {
"$exists": true
}
}
You can then use the query object in your find() query
collection.find(query).toArray(function(err, docs) {
// access the docs array here
})