I'm getting this array of user emails from the post data. I want to find the _id related to each email. I tried this for loop:
var studentIds = [];
for (var i = studentEmails.length - 1; i >= 0; i--) {
var email = studentEmails[i];
User.findOne({"email": email}, (err, student) => {
if (err) {
console.log("ERROR" + err);
}
if (student) {
var id = student._id;
studentIds.push(id);
console.log("STUDENT: " + student);
}
});
}
// Outside for loop
console.log('END');
However, this logs the following:
END
STUDENT: { _id: 5a11e667d7333203337cd9a4,
name: 'Patrick Jacobs',
email: 'windvaan#live.nl',
password: '$2a$10$CiSw/VH1HCaPtW6Sjz0X4.4avVoLsAH6iyF3FhidorahwLt1WDXoC',
__v: 0 }
STUDENT: { _id: 5a0f7dfb64b5a6000417c662,
name: 'Carlo Jacobs',
email: 'carlojacobs91#gmail.com',
password: '$2a$10$fiIosS4Jo5ehuCp3TfltSOnpypPMWSMvzlb7phRWmNGBtDz5W1rCG',
__v: 0 }
As you can see, the END is being printed first. I don't want that. I'm assuming the for loop is asynchronous? How can I make it synchronous?
Thx in advance!
The solution would be
var studentIds = [];
var loopRecords = function (records, cb) {
if (!records.length) return cb();
var email = records.shift();
User.findOne({"email": email}, (err, student) = > {
if (err) {
console.log("ERROR" + err);
}
if (student) {
var id = student._id;
studentIds.push(id);
console.log("STUDENT: " + student);
}
return loopRecords(records, cb);
}
}
loopRecords(studentEmails,function () {
console.log('END');
})
It is not the for loop, but the User.findOne call that is asynchronous.
Following this answer, you could use streamline.js; try the following to make the call synchronous.
var result = User.findOne({"email": email}, _);
if (result === null) {
console.log("ERROR" + err);
}
var id = result._id;
studentIds.push(id);
console.log("STUDENT: " + result);
Related
I am creating backend APIs for a Twitter clone. The below API shows the profile of a user. I want to show the tweets of the people that this user is following. But in my response the tweets array is returning an empty array even though I have pushed the data into this array.
Can somebody help me understand why is the tweets array empty in the response?
app.get('/api/profile', auth, function (req, res) {
var email1 = req.user.email;
var followers_data = [];
var tweets = [];
follower.find({ emailoffollowee: email1 }, (err, results) => {
if (err)
console.log(err);
else {
results.map((d, k) => {
followers_data.push(d.emailoffollower);
})
for (var i = 0; i < followers_data.length; i++) {
Tweet.find({ author: followers_data[i] }, (err, results1) => {
if (err)
console.log(err);
else {
results1.map((d, k) => {
tweets.push(d);
})
}
})
}
res.json({
isAuth: true,
id: req.user._id,
email: req.user.email,
name: req.user.firstname + req.user.lastname,
followers: followers_data,
tweet: tweets
});
}
})
.catch(error => {
console.log(error);
})
});```
You Have Tweet.find() which is an asynchronous function, to resolve the problem I used async/await
app.get('/api/profile', auth, function (req, res) {
var email1 = req.user.email;
var followers_data = [];
var tweets = [];
follower.find({ emailoffollowee: email1 }, async (err, results) => {
if (err)
console.log(err);
else {
results.map((d, k) => {
followers_data.push(d.emailoffollower);
})
for (var i = 0; i < followers_data.length; i++) {
let results1 = await Tweet.find({ author: followers_data[i] });
results1.map((d, k) => {
tweets.push(d);
})
}
res.json({
isAuth: true,
id: req.user._id,
email: req.user.email,
name: req.user.firstname + req.user.lastname,
followers: followers_data,
tweet: tweets
});
}
})
.catch(error => {
console.log(error);
})
});
I recommend you to read this article async/await
I have stored 2775 urls in my mlab database and then I take each URL down to get more information. All of the URL I store in an Array then pass it into a function to process .However, The code only run up to about 1700 urls and process it and then stop. Here is my code (sorry about the code, this is my first time using stackoverflow :
Product.find({}, (err, foundProducts) => {
if (err) {
console.log("err " + err);
} else {
foundProducts.forEach(function(foundProduct) {
var updateProduct = service.updateTikiProduct(foundProduct.url);
});
}
});
updateTikiProduct: function(url) {
const options = {
url: url,
json: true
};
request(options,
function(err, res, body) {
// SOME code to crawl data
Product.findOneAndUpdate({
url: options.url
}, {
$set: {
name: name,
brand: brand,
store: store,
location: location,
base_category: categoryType,
top_description: topDescription,
feature_description: featureDescription
}
}, {
upsert: true,
new: true
}, (err, createdProduct) => {
if (err) {
reject(err);
} else {
var currentDate = new Date();
if (!createdProduct.hasOwnProperty("price")) {
createdProduct.price.push({
current: currentPrice,
origin: originPrice
});
createdProduct.save();
} else if (createdProduct.hasOwnProperty("price") &&
createdProduct.price[0].date.getDate() != currentDate.getDate()) {
createdProduct.price.push({
current: currentPrice,
origin: originPrice
});
createdProduct.save();
console.log("Update price");
}
counter++;
console.log("url : " + options.url);
console.log("Created product " + counter + " success!");
}
});
}
i guess mongo have limits to get items from db, you should try findAll or https://stackoverflow.com/a/3705615/4187058
I think your code is not processing all the elements is because you are processing all the elements in parallel, which will stop processing at one time when the memory will get full.
foundProducts.forEach(function(foundProduct) {
var updateProduct = service.updateTikiProduct(foundProduct.url);
});
what you should do is process them in series. you can use async await for that, do the following changes it will work :-
for(let foundProduct of foundProducts){
var updateProduct = await
service.updateTikiProduct(foundProduct.url);
};
Why wont usernametoid function return the acual id? cause im trying to send the result of the userdata as the return. In this case, i want to only send the userdata`s _id attribute. but it seems like it wont work.
console.log(userdata._id); // works
return resolve(userdata._id); // wont work.
output of variable userdata:
{
cash: 7300002,
bank: 0,
xp: 0,
rank: 1,
points: 1,
location: 1,
health: 100,
protection: 1,
attack: 1,
family: '0',
password: 'jKa4qC7pRCgE5jvzD9Vv1pRUNxFlQEM7Jpq/IoJ/sUWOAv1Wx1RI/j/Vu6Zf8zyNkCFcg3QBtdfAC+lmPS8KIA==',
profileImageURL: 'modules/users/client/img/profile/default.png',
roles: [ 'user' ],
created: Sat Aug 27 2016 12:33:55 GMT-0400 (EDT),
__v: 0,
username: 'signature',
provider: 'local',
salt: '4ySlrr9ggESxBB3dR5bx4Q==',
_id: 57c1c0f3b6b20c011242bf22 }
when i do: `return resolve(userdata._id) it would get this error:
/server/factory/user_factory.js:52
return resolve(userdata._id);
^
TypeError: Cannot read property '_id' of null
node.js call:
var articles = require('../controllers/articles.server.controller'),
path = require('path'),
mongoose = require('mongoose'),
Article = mongoose.model('Article'),
Users = mongoose.model('User'),
errorHandler = require(path.resolve('./modules/core/server/controllers/errors.server.controller'));
var userFunc = require('../factory/user_factory.js');
app.post('/api/kill', function (req, res) {
console.log("starting");
var username = "signature";//req.query.username;
var result = ["test service"];
var data = req.user;
userFunc.usernametoid(username).then( function (otherplayerid) {
if (!(otherplayerid)) {
console.log("other player is acually " + otherplayerid);
result.push("denne brukeren finnes ikke! " + otherplayerid);
} else {
userFunc.usernametoid(otherplayerid).then( function (otherplayer) {
if (data.location != otherplayer.location) {
result.push("Du er ikke i samme lokasjon som " + username);
result.push(data.location + " vs " + otherplayer.location);
} else {
userFunc.addCash(req.user._id,100000);
result.push("starter lokasjonisering");
}
});
}
res.json(result);
});
});
user factory:
var articles = require('../controllers/articles.server.controller'),
path = require('path'),
mongoose = require('mongoose'),
Article = mongoose.model('Article'),
Users = mongoose.model('User'),
errorHandler = require(path.resolve('./modules/core/server/controllers/errors.server.controller'));
exports.usernametoid = usernametoid;
function usernametoid(id) {
return new Promise( function (resolve, reject) {
var query = Users.findOne( { username : id } );
// var query = Users.find({_id:id});
query.exec(function(err, userdata) {
if (err){
return reject({err : 'Error while getting user info'});
}
console.log(userdata._id);
return resolve(userdata);
});
}, function (){
return reject({err : 'error while fetching cash'});
});
}
Because you are not passing correctly the fetched user to the query.exec.
You need to do:
var Users = require('../models/users-model.js');
function usernametoid(id) {
return new Promise( function (resolve, reject) {
Users.findOne({ username : id }).then( function(user){
//If you use lodash you can do _.isNull(user)
if(user == null){
return reject({error : 'User not found'});
}
user.exec(function(userdata, error) {
if(userdata){
return resolve(userdata);
}
if(error){
return reject({error : 'Error while executing query'});
}
});
});
});
}
I don't really get why you are importing Users Model like that. I do not think Node will be able to fetch it like that.
And, you should require mongoose in your server.js
To catch the rejection you need the following code:
UserFactory.userNameToId(id).then( function(response){
if(response.error){
console.log('error '+response.error);
}
if(response){
console.log('Got response '+response);
}
});
I m doing a javascript function using mongoose to find a group which contains a list of users emails, that part works perfectly. After I want to find each user of the list and add the new group name instead of the old group name, I don't know why, but it doesn't work, the function returns me the group before doing the for loop, and the users are not modified.
Here is my user model :
var userSchema = mongoose.Schema({
local : {
email : String,
password : String,
}
groups : { type: [String], default: []}
});
And here my Group model :
var groupSchema = mongoose.Schema({
title : String,
creator : String,
listOfUsers : { type: [String], default: []}
});
And here my function :
Group.findOne({ '_id': groupId}, function (error, group){
var oldTitle = group.title;
group.title = req.body.title;
group.save();
if(error){
throw (error)
}
for(var i = 0; i < group.listOfUsers.length;i++){
User.findOne({'local.email': group.listOfUsers[i]}, function(error,user){
if(error){
throw (error)
}
for(var j=0;j<user.groups.length;j++){
if(user.groups[j] == oldTitle){
user.groups[j] = group.title;
user.save();
}
}
});
}
return res.json(group);
you can use async to fix the callback problem
async.waterfall(
[
function (callback) {
Group.findOne({
'_id': groupId
}, function (error, group) {
if (error) {
throw (error)
} else {
callback(null, group);
}
})
},
function (group, callback) {
for (var i = 0; i < group.listOfUsers.length; i++) {
User.findOne({
'local.email': group.listOfUsers[i]
}, function (error, user) {
if (error) {
throw (error)
} else {
callback(null, user, group);
}
});
}
},
function (user, group, callback) {
var oldTitle = group.title;
group.title = req.body.title;
for (var j = 0; j < user.groups.length; j++) {
if (user.groups[j] == oldTitle) {
user.groups[j] = group.title;
user.save();
}
}
callback(null, 'done');
}
],
function (err, result) {
console.info("4");
console.info(err);
console.info(result);
});
forgive me if i made any mistake, it is always hard to write code without data, i hope you will understand how i wanted to solve.
and don't forget
var async = require('async');
at the beginning
You should do user.save() only after for loop is finished. I updated for loops with forEach which I feel more comfortable to use.
Group.findbyId(groupId, function(err, group) {
var oldTitle = group.title;
group.title = req.body.title;
if (group.save()) {
listOfUsers.forEach(function(groupUser) {
User.findOne({'local.email' : groupUser}, function (err, user) {
if(user) {
user.group.forEach(function(userGroup) {
if (userGroup == oldTitle) {
userGroup = group.title;
}
})
user.save();
}
});
});
res.json(group);
} else {
res.status(400).json({messsage: 'Error while saving group!'});
}
});
I created a function to save data into mongoDB with logic below, but I really have difficulty to refactor the code and make it cleaner, there are so many annoying code duplication, how can I have DRY principle?
Logic:
1. pass in a flag to decide either close DB connection or not at end.
2. create different mongoDB models according to the passed in returnedArray and save into DB.
var saveArrayToDB = function(returnedArray, flagToCloseDBConnection) {
var objectToSave,
object,
type = returnedArray[0].type,
arrayToSave = [];
if (type === 'user') {
for (var i = 0; i < returnedArray.length; i++) {
object = returnedArray[i];
objectToSave = new User({
fullName: object['full_name'],
activatedAt: object['activated_at'],
location: object['location'],
timezone: object['timezone'],
imageURL: object['mugshot_url'],
stats: object['stats']
});
arrayToSave.push(objectToSave);
}
User.create(arrayToSave, function(err) {
if (err) {
console.log('err ' + err);
}
if(flagToCloseDBConnection) {
mongoose.connection.close();
}
});
} else if (type === 'group') {
for (var j = 0; j < returnedArray.length; j++) {
object = returnedArray[j];
objectToSave = new Group({
fullName: object['full_name'],
createdAt: object['created_at'],
stats: object['stats'],
url: object['web_url']
});
arrayToSave.push(objectToSave);
}
Group.create(arrayToSave, function(err) {
if (err) {
console.log('err ' + err);
}
if(flagToCloseDBConnection) {
mongoose.connection.close();
}
});
} else {
objectToSave = null;
console.log('ERROR: unrecognized type in data. Not saved.');
}
};
Just to add on to what #JohnnyHK commented on your question, it would be best if you keep your mongoose connection open during your application lifecycle. Other than that you could use some JavaScript functions like map() to initialize the arrays, define common callback functions that you can reuse in both create and map methods:
var saveArrayToDB = function(returnedArray, flagToCloseDBConnection) {
var type = returnedArray[0].type,
arrayToSave = [];
var callback = function(err) {
if (err) { console.log('err ' + err); }
};
var newUser = function(u){
return new User({
fullName: u['full_name'],
activatedAt: u['activated_at'],
location: u['location'],
timezone: u['timezone'],
imageURL: u['mugshot_url'],
stats: u['stats']
});
};
var newGroup = function(g){
return new Group({
fullName: g['full_name'],
createdAt: g['created_at'],
stats: g['stats'],
url: g['web_url']
});
};
if (type === 'user') {
arrayToSave = returnedArray.map(newUser);
User.create(arrayToSave, callback);
} else if (type === 'group') {
arrayToSave = returnedArray.map(newGroup);
Group.create(arrayToSave, callback);
} else {
console.log('ERROR: unrecognized type in data. Not saved.');
}
};
No need for closing the connection. Here's an already much improved version:
var factories = {
'user': {
method: function(object){
return {
fullName: object['full_name'],
activatedAt: object['activated_at'],
location: object['location'],
timezone: object['timezone'],
imageURL: object['mugshot_url'],
stats: object['stats']
};
},
model: User
},
'group': {
method: function(object){
return {
fullName: object['full_name'],
createdAt: object['created_at'],
stats: object['stats'],
url: object['web_url']
};
},
model: Group
}
}
var saveArrayToDB = function(returnedArray) {
var saveQueue=[],
factory = factories[returnedArray[0].type];
if(!factory){
return console.log('ERROR: unrecognized type in data. Not saved.');
}
returnedArray.forEach(function(item){
saveQueue.push(factory.method(item));
});
factory.model.create(saveQueue, function(err){
if(err){
console.log('err ' + err);
}
});
};
(You don't need to pass document instances, plain objects are good enough for Model.create)