I need help in this query mongodb with nodejs - mongodb

Question

The query is returning double value, can you help me with this?
the problem stay in unwind ?
is a consultation that consolidates the debits and credits of the db...
with aggregate...
Code:
My DAO ( MongoDB + NodeJS ) :
ListarDebitosDAO.prototype.consolidado = function(usuario,res,req){
this._connection.open(function(err, mongoclient){
mongoclient.collection("contas", function(err, collection){
collection.aggregate([{
$match : {usuario : usuario}},{
$unwind: "$debitos"
},{
$unwind: "$creditos"
}, {
$group: {
"_id" : usuario,
"debitos": {
$sum: "$debitos.debito"
},
"creditos" : {
$sum: "$creditos.credito"
}
}
}])
.toArray(function(error, results){
console.log(results)
var debitoConsolidado = results[0].debitos;
var creditoConsolidado = results[0].creditos;
res.render('dashboard', {debitoConsolidado,nome_usuario: req.session.nome,creditoConsolidado})
});
// mongoclient.close();
});
});
}
My collection ( exemple ) :
{
"_id" : ObjectId("5a09113b42e54fb49230fa37"),
"usuario" : "sara",
"creditos" : [
{
"nome_do_credito" : "credito inicial",
"credito" : 0
},
{
"nome_do_credito" : "salario",
"credito" : 1200
}
],
"debitos" : [
{
"nome_do_debito" : "debito inicial",
"debito" : 0
},
{
"nome_do_debito" : "Vivo",
"debito" : 200
},
{
"nome_do_debito" : "Vivo",
"debito" : 600
}
]
}
My atual output:
{ "_id" : null, "debitos" : 1600, "creditos" : 3600 }
I need :
{ "_id" : null, "debitos" : 800, "creditos" : 1200 }
enter code here

Answer 1

The problem is that you are trying to use both unwind simultaneously, it is creating duplicate entries hence the sum of credit and debit is coming wrong.
I guess what you can do is do sequential unwind and grouping for both credit and debit
collection.aggregate([{
$match : {usuario : usuario}},{
$unwind: "$debitos"
}, {
$group: {
"_id" : usuario,
"debitos": {
$sum: "$debitos.debito"
},
"creditos" : "$creditos"
}
},
{
$unwind: "$creditos"
},
{
$group: {
"_id" : usuario,
"creditos" : {
$sum: "$creditos.credito"
}
"debitos": "$debitos"
}
}
])
I am sure either this or some variant should work for you.

Answer 2

It can be as simple as this:
db.contas.aggregate([
{
$project: {
_id: 1,
usario: 1,
debitos: {
$reduce: {
input: "$debitos",
initialValue: 0,
in: { $add: [ "$$value", "$$this.debito" ] }
}
},
creditos: {
$reduce: {
input: "$creditos",
initialValue: 0,
in: { $add: [ "$$value", "$$this.credito" ] }
}
}
}
}
]);
You can use just one projection and reduce the arrays by summing their members.