How to update a collection document using multiple criteria - node.js

Question

I have this document in collection "registosSRS":
{
"_id" : ObjectId("5a3a2b47d04b7e07f8a273dc"),
"sessao" : "5",
"valorRelacao" : "4.89",
"valorObjectivo" : "4.97",
"valorAbordagem" : "4.88",
"valorGeral" : "4.92",
"cliente_id" : "5a1407c8099ca208e48170a5",
"email" : "mgoncalves#psi.uminho.pt",
"data" : 1513761607431
}
and this document in collection sessao. I've created this document in another place, and set dadosSRS to {} because I want to later change this value. Is this possible to add this value without having created it?
"_id" : ObjectId("5a3a2b41d04b7e07f8a273db"),
"cliente" : ObjectId("5a1407c8099ca208e48170a5"),
"data" : 1513761601705,
"numero" : "5",
"dadosORS" : ObjectId("5a3a2b41d04b7e07f8a273da"),
"dadosSRS" : {
}
Then I'm looking in collection sessao for a client and number os session as in registosSRS, to add the registosSRS id.
mongoClient.collection('sessao', function(err,collection){
collection.update(
{cliente:result.cliente_id, numero:dadosSRS.sessao},
{$set: {'dadosSRS':dadosSessao.dadosSRS}},
function(result){
if (err) throw err;
console.log(result);
console.log('encontrou registo do cliente na collection registoSRS: ' + result);
});
but the result is null, although I have the client and the session number. What am I doing wrong?

Answer 1

In your callback you have only one argument which is essentially the error object hence the result is null since there is no error thrown from the update option. You need a second argument which returns the actual result object. You are using the wrong update method which returns the result object if the command was executed successfully, not the actual document.
From the documentation, the result object has the following properties:
Name Type Description
result Object The raw result returned from MongoDB, field will vary depending on server version.
Properties
Name Type Description
ok Number Is 1 if the command executed correctly.
n Number The total count of documents scanned.
nModified Number The total count of documents modified.
connection Object The connection object used for the operation.
matchedCount Number The number of documents that matched the filter.
modifiedCount Number The number of documents that were modified.
upsertedCount Number The number of documents upserted.
upsertedId Object The upserted id.
You instead need to use findOneAndUpdate which will return the updated document if found
const { ObjectId } = require('mongodb'); // or ObjectID
// or var ObjectId = require('mongodb').ObjectId if node version < 6
const safeObjectId = s => ObjectId.isValid(s) ? new ObjectId(s) : null;
collection.findOneAndUpdate(
{ 'cliente': safeObjectId(result.cliente_id), 'numero': dadosSRS.sessao },
{ '$set': { 'dadosSRS': dadosSessao.dadosSRS } },
{ 'returnOriginal': true },
function(err, result) { // <-- add result as a second argument in the callback
if (err) throw err;
console.log(result);
console.log('encontrou registo do cliente na collection registoSRS: ' + result);
});