Develop Reference

node.js: Return from function not acting as expected

I'm very new to javascript/node.js and I'm having trouble with the following code. This is the handler for API an call. The 2nd code segment is just like the 1st, except there is an additional database lookup Merchant.findOne(...), and therefor the 'newTransaction.save()' function is nested one level deeper.
Both code segments return the 'output' variable value correctly. However, the second code segment does NOT also properly save the 'newTransaction' to the Mongo database.
I'm pretty sure the issue has to do with how/when the code returning from newTransaction.save(function (err, transaction){..} but I can't seem to get it straightened out.
I have been looking all over the internet trying to understand and fix this, with no success. Any help is appreciated...
Here is the older, simpler code that works as expected:
handler : function(request, reply) {
var output = {
"success": true,
"operations": [],
"epoch": Date.now()
};
Terminal.findById(request.payload.deviceNumber, function (err, terminal) {
if (err) {
return reply(Boom.internal('Error looking up terminal.', err));
}
if (terminal) {
ticket.quote("bitstamp", "USD", 1, function (err, exchangeRate) {
if (err) {
console.error(err);
return reply(Boom.internal('Error obtaining ticket quote.', err));
}
var newTransaction = new Transaction({
terminal: request.payload.deviceNumber,
merchant: terminal.merchant,
ccExchangeRate: exchangeRate.buy,
fiatAmtDue: request.payload.transactionValue,
ccAmtDue: ccAmtDueTruncated
});
newTransaction.save(function (err, transaction){
if (err) {
return reply(Boom.internal('Error creating new transaction.', err));
}
output.operations.push(
{
"control": "KeyPairGenControl",
"rand": cc.pseudoRandomBytes(32).toString('hex'),
"follow": {
"url": "/pos/v1/AddressAndEncKey",
"post": {
"transactionId": transaction.transactionId
}
}
}
);
return reply(output);
});
});
} else {
return reply(Boom.internal('Error looking up terminal.', err));
}
});
}
Here is the new code that does NOT save the newTransaction data into the Mongo DB.
handler : function(request, reply) {
var output = {
"success": true,
"operations": [],
"epoch": Date.now()
};
Terminal.findById(request.payload.deviceNumber, function (err, terminal) {
if (err) {
return reply(Boom.internal('Error looking up terminal.', err));
}
if (terminal) {
Merchant.findOne({merchantId: terminal.merchant}, function(err, merchant) {
if (err) {
console.log('Cannot find merchant');
return reply(output);
}
var processor = merchant.backendPaymentProcessor.name;
var localCurrency = merchant.localFiatCurrency;
//###################
ticket.quote(processor, localCurrency, 1, function (err, exchangeRate) {
if (err) {
console.error(err);
return reply(Boom.internal('Error obtaining ticket quote.', err));
}
var newTransaction = new Transaction({
terminal: request.payload.deviceNumber,
merchant: terminal.merchant,
ccExchangeRate: exchangeRate.buy,
fiatAmtDue: request.payload.transactionValue,
ccAmtDue: ccAmtDueTruncated
});
newTransaction.save(function (err, transaction){
if (err) {
return reply(Boom.internal('Error creating new transaction.', err));
}
output.operations.push(
{
"control": "KeyPairGenControl",
"rand": cc.pseudoRandomBytes(32).toString('hex'),
"follow": {
"url": "/pos/v1/AddressAndEncKey",
"post": {
"transactionId": transaction.transactionId
}
}
}
);
return reply(output);
});
//return reply(output);
});
//###################
});
} else {
return reply(Boom.internal('Error looking up terminal.', err));
}
});
}

I did a diff of your 2 version:
Check 1
ticket.quote
Callback are identical for both version
processor, localCurrency are different
Is exchangeRate pass into callback correct?
Check 2
newTransaction.save
newTransaction and callback for .save are setup identical
Check(console.log()) the values used in setting up new Transaction({...})
Check transaction object received by callback
Check/debug the code of Transaction.save().
I don't think the issue is with the code you posted. Both version reached return reply(output); inside newTransaction.save's callback. Very likely issue is inside Transaction class or Transaction.save() logic.
One scenario I can think of is when a transaction failed:
Transaction object is available (even for failed transaction)
Transaction Class / Transaction.save() does not write to db because transaction failed
Transaction.save() pass transaction object to callback, but NOT setting err, even when it should.

Mongoose having a feature to specify the collection name under the schema, or as the third argument when declaring the model. Otherwise it will use the pluralized version given by the name you map to the model.
Mongoose official doc having following statement:
Mongoose by default produces a collection name by passing the model name to the utils.toCollectionName method. This method pluralizes the name. Set this option if you need a different name for your collection.
schema-mapped:
new Schema({ <key>: <value>},
{ collection : '<collection name>' }); // collection name
model-mapped:
mongoose.model('<Model name>',
new Schema({ <key>: <value>}),
'<collection name>'); // collection name
You may also find same here

Why getting error when updating MongoDb?

I am building backend with MEAN stack, but when I try to update document in the db i am getting an error:
topUp = function(name, amount, callback) {
User.updateOne(
{ "name" : name },
{ $set: { "wallet": amount } },
function(err, results) {
console.log(results);
callback();
});
};
TypeError: User.updateOne is not a function
But e.g. findOne() works fine:
User.findOne({
name: decoded.name
}, function(err, user) {
if (err) throw err;
i
f (!user) {
return res.status(403).send({success: false, msg: 'Authentication failed. User not found.'});
} else {
//res.json({success: true, info: {wallet: user.wallet, userPic: user.userPic}});
topUp(decoded.name, amount, function() {
User.close();
});
}
});
"User" is a Mongo model file.

I think it's not defined in the database driver that you might be using. I think you are using Mongoose and updateOne() is not available there. You cannot use all native mongodb functions with all drivers

There is an en existing enhancement request for this https://github.com/Automattic/mongoose/issues/3997 , but maybe the findByIdAndUpdate() method could be a close alternative.

nodejs and MongoDB's collection.find() does not respond

I have about 30,000 documents in a MongoDB collection. And have been stuck in developing a node.js script to retrieve only the records with a specific string key-value pair.
this query on MongoDB server returns me the exact results I've been looking for:
db.getCollection('posts').find({authorName: "Ashwin-kumar"})
Returns me about 33 documents instantly. Likewise I've about 40 authors with different names.
Here's my node.js script to retrieve posts by authorName (Yes, it is based on Name, a string, as there is no ID for these authors :( ):
var fs = require('fs'),
request = require('request'),
async = require("async"),
assert = require('assert');
_ = require('lodash'),
MongoClient = require('mongodb').MongoClient;
var db, postsCollection, postCol;
async.series([dbConnect, checkCollection, createMeta, dbClose], function(){
console.log("Executed all calls in series.");
process.exit(0);
});
function dbConnect(callback){
MongoClient.connect("mongodb://localhost:27017/jPosts", function(pErr, pDb) {
if(pErr) {
console.dir(pDb);
return 0;
}
db = pDb;
callback();
});
}
function dbClose(callback){
db.close(true, function (err) {
if (err) console.error(err);
else console.log("close complete");
callback();
});
}
function checkCollection(callback) {
db.collection('posts', function(err, collection) {});
postsCollection = db.collection('posts');
postCol = db.collection('posts');
callback();
}
function createMeta(callback){
var meta = [];
postsCollection.aggregate([
{
$group : {_id : "$authorName"}
}]).toArray(function(err, result) {
assert.equal(err, null);
async.forEachLimit(result, 1, function(pPost, callback) {
getPosts(pPost._id, callback);
}, function(err) {
console.log(err);
callback();
});
});
}
function getPosts(pAuthor, callback){
var cursor = postCol.find({ "authorName": pAuthor});
cursor.toArray(function(err,items){
if(err)
callback(err);
else
callback(null, items);
});
}
This does not seem to work for me. cursor.toArray() does nothing but wait forever. Is it because of too many fields in each document?
I tried to get the count of the documents the cursor fetched and it works well.
function getPosts(pAuthor, callback){
var cursor = postCol.find({ "authourName": pAuthor});
cursor.count().then(function(items_count) {
console.log(items_count);
callback();
});
}
Also, I tried the cursor's .each method to iterate the documents fetched. But no luck yet.
function getPosts(pAuthor, callback){
var cursor = postCol.find({ "authourName": pAuthor});
cursor.each(function(err, doc) {
assert.equal(err, null);
if (doc != null) {
console.dir(doc);
} else {
console.log(err);
}
});
}
Am I missing something here? What else can be done to make this work? Is there any issues with the way I'm using async?
P.S: The idea here is to query the dump and generate the PDF's for authours in the jPost collection.
P.S 2: Here's a sample document
{
"_id" : ObjectId("571d36b55672f713fe346a66"),
"id" : 56517,
"authorName" : "Ashwin-kumar",
"comment_count" : 380,
"tagline" : "... Opinions you don't really need",
"vote_count" : 5152,
"exclusive" : null,
"post": [
],
"post_comments" : [
//comment_count objects
],
"date" : "2016-03-27"
}
(I've omitted post & post_comments parts for brevity.)

try this:
var collection = db.collection("collection_name");
collection.find({authourName: "Ashwin-kumar"}).toArray(function (err,items) {
if (err) {
console.dir(err);
} else {
//do something with items array
console.dir(items);
}
});

Did you check what is the value of pAuthor in getPosts? Because when you do aggregation, you receive a collection of objects with _id field (not authourName), so you should do:
// not sure why you need meta array, at least it's not used in the code you provided
meta.push({
author: pPost._id
});
getPosts(pPost._id, callback);

mongoose "Find" with multiple conditions

I am trying to get data from my mongoDB database by using mongoose filters. The scenario is that each user object in the database has certain fields like "Region" or "Sector".
Currently I am getting all the users that contain the keyword "region" in there object like so:
// Filter all healthcare bios by region
app.get('/user',function(req, res) {
// use mongoose to get all users in the database
User.find({region: "NA"}, function(err, user)
{
// if there is an error retrieving, send the error. nothing after res.send(err) will execute
if (err)
{
res.send(err);
}
// return all todos in JSON format
console.log(user);
res.json(user);
});
});
How can put some conditions in mongoose that it return users that contain both "region" && "Sector" in their objects. Currently its only returning the user which have the region keyword in them.
I have tried using $and operator but I couldn't get it to work.

app.get('/user',function(req, res) {
User.find({region: "NA",sector:"Some Sector"}, function(err, user)
{
if (err)
{
res.send(err);
}
console.log(user);
res.json(user);
});
});
If you want data with either region:"NA" or sector:"Some Sector". you can use $or operator.
User.find({$or:[{region: "NA"},{sector:"Some Sector"}]}, function(err, user)
{
if (err)
{
res.send(err);
}
console.log(user);
res.json(user);
});

If you want results that contain any region or sector as long as both are present at the same time you need the following query in your User.find:
{region: {$exists:true},sector: {$exists:true}}
, is the equivalent of $and as long as you are searching different fields.

const dateBetweenDates = await Model.find({
$or: [
{
$and: [
{ From: { $gte: DateFrom } },
{ To: { $lte: DateTo } },
], // and operator body finishes
},
{ _id: req.user.id},
], //Or operator body finishes
})

For anyone else trying to find with multiple conditions using mongoose, here is the code using async/await.
app.get('/user', async (req, res) {
const user = await User.find({region: "NA",sector:"Some Sector"});
if (user) {
// DO YOUR THING
}
});

mongoDB node.js findAndModify troubles

I am doing an online course about MongoDB which is unfortunately a little out of date. It seems some of the functions have changed (course is using version 1.4 while I am using 3.0.)
Here is the code I am having trouble with, which I have tried to bring up to date with the current version of MongoDB:
app.js
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect('mongodb://localhost:27017/course', function(err, db) {
if (err) throw err;
db.collection['counters'].findAndModify({
query: {
name: 'comments'
},
update: {
$inc: {
counter: 1
}
},
new: true
}, function(err, doc) {
if (err) throw err;
if (!doc) {
console.dir('No counter found for comments.');
} else {
console.dir('Number of comments: ' + doc.counter);
}
return db.close();
});
});
If I run the same findAndModify through the Mongo shell I get the anticipated result (increment the counter and display the new document,) but when I run this with node it has no effect on the database and throws this error:
TypeError: Cannot call method 'findAndModify' of undefined
Any tips?

Please try:
db.counters('counters').findAndModify
instead of:
db.collection['counters'].findAndModify

use this now:
db.collection('counters').findOneAndUpdate(
{name: 'comments'}, //query
{$inc: {counter: 1}}, //update
{ //options
upsert: true, // create the doc when it's not there
returnOriginal:false // return the modified doc *(new is not supported here!)
},
function(err, r){ //callback
if(err) throw err;
console.log('counter: '+r.value.counter);
}
);

Whoops, I just had the wrong kind of brackets. Should have had:
db.collection('counters')
instead of
db.collection['counters']
Almost like T_G said.

From the mongodb docs:
Existing collections can be opened with collection
db.collection([[name[, options]], callback);
If strict mode is off, then a new collection is created if not already
present.
So you need to do this:
db.collection('counters', function(err, collection){
collection.findAndModify({
query: {
name: 'comments'
},
update: {
$inc: {
counter: 1
}
},
new: true
}, function(err, doc) {
if (err) throw err;
if (!doc) {
console.dir('No counter found for comments.');
} else {
console.dir('Number of comments: ' + doc.counter);
}
});
});