Query with variables not working using nodejs ,express, mongojs and mongodb - node.js

Question

My application needs to get the result of this query (this is already giving the correct result in mongoDb):
var denominator = db.getCollection('Transactions').aggregate({
$group: {
"_id": null,
"Alltotal": {$sum:"$transAmount"}
}
};
db.getCollection('Transactions').aggregate([{
$group: {
_id: '$merchantCode',
total: {
$sum: { $multiply: ['$transAmount', 100 ]}
}}},
{ $project: {
percentage: {
$divide: [
"$total",
denominator.toArray()[0].Alltotal
]
}
}
}
])
Now here is how I am trying to execute it:
var express = require('express');
var app = express();
var mongojs = require('mongojs');
var dbTransaction = mongojs('dataAnalysisDb',['Transactions']);
app.get('/Transactions',function(req,res){
var denominator = dbTransaction.Transactions.aggregate([{
$group: {
_id: 'null',
total: { $sum: '$transAmount' }
}
}]);
dbTransaction.Transactions.aggregate([{
$group: {
_id: '$mtype',
total: {
$sum: { $multiply: ['$transAmount', 100 ]}
}}},
{ $project: {
percentage: {
$divide: [
"$total",
denominator.toArray()[0].total
]
}
}
},
{ $sort : { _id : 1, posts: 1 } }
], function(err,docs){
console.log(docs); //this is for testing
res.json(docs);
});
});
I think this is not working because I am not sending the variable in the correct way to the server and when I use it on the operation it is not defined. I will appreciate any suggestion on how to fix it.
Thank you

Answer 1

I found a way to solve it and it might not be the best but it worked, I leave it here for whoever else needs it
var denominator = dbTransaction.Transactions.aggregate([{
$group: {
"_id": null,
"Alltotal": {$sum:"$transAmount"}
}}]).toArray(function(err,items){
console.log(items[0].Alltotal); //this is for testiong
dbTransaction.Transactions.aggregate([{
$group: {
_id: '$mtype',
total: {
$sum: { $multiply: ['$transAmount', 100 ]}
}}},
{ $project: {
percentage: {
$divide: [
"$total",
items[0].Alltotal
]
}
}
},
{ $sort : { _id : 1, posts: 1 } }
],function(err,docs){
console.log(docs); //this is for testing
res.json(docs);
});
});