Develop Reference

Node Js: Remove string array element from mongoDB

I have a user schema as follows:
const UserSchema = new mongoose.Schema({
skills: [String]
});
module.exports = mongoose.model("User", UserSchema);
And a Fetch request to delete a skill as follows:
const deleteItem = async (id) => {
try {
await fetch(`http://localhost:5000/api/user/deleteskill`, {
method: "DELETE",
headers: { "Content-Type": "application/JSON", token: accessToken },
body: JSON.stringify({ userid: userid , skill:id}),
})
.then((res) => res.json())
.then((data) => {
console.log("USER SKILLS:", data.userskills);
});
} catch (err) {
console.log(err);
}
};
Server
const deleteSkill = async (req, res) => {
try {
const user = await User.findById(req.body.userid)
//user.skills.pull(req.body.skill);
// removeskill = user.skills.filter(function(item) {
// return item !== req.body.skill
// })
if (user.skills.includes(req.body.skill)) {
res.status(400).json("Item Still Exists");
} else {
res.status(200).json("Item Deleted");
}
} catch (error) {
res.status(500).send({ error: error.message });
}
};
the array is in the following structure
[
'skill1', 'java', 'skill5'
]
I have tried to remove the user skill from the array in several ways but I still get res.status(400).json("Item Still Exists");. What I'm doing wrong?

Use the findOneAndUpdate method to find a document with the user id and update it in one atomic operation:
const deleteSkill = async (req, res) => {
try {
let message = "Item Deleted";
let status = 200;
const user = await User.findOneAndUpdate(
{ _id: req.body.userid },
{ $pull: { skills: req.body.skill } },
{ new: true }
)
if (user && user.skills.includes(req.body.skill)) {
message = "Item Still Exists";
status = 400;
} else if (!user) {
message = "User Not Found";
status = 404;
}
res.status(status).send({ message });
} catch (error) {
res.status(500).send({ error: error.message });
}
};

I believe you want to remove skills from the database then the following function could help you out.
var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
MongoClient.connect(url, function(err, db) {
if (err) throw err;
var dbo = db.db("mydb");
var myquery = { userid: userid, skillid: skillid};
dbo.collection("skills").deleteOne(myquery, function(err, obj) {
if (err) throw err;
console.log("1 document deleted");
db.close();
});
});

You have a method of removing elements from arrays, if you want to remove the first one you could use array.shift (more on it here), but if you want to delete it completely from your database you could always, find it and then update it.

User.update({ _id: userid }, { $pull: { "skills": "[skill]" }})

How to find then Update a user record Mongo/Mongoose

I'm getting user.update is not a function when running this code. I have been unable to find good mongo/mongoose documentations online.
//Add Event
app.post("/addEvent", (req, res, next) => {
const event = req.body.event;
console.log(req.user.id);
console.log(event);
User.find({ _id: req.user.id }, function(err, user) {
if (err) {
console.log(err);
return next(err);
}
if (user) {
user.update(
{
_id: req.user.id
},
{
$push: { events: event }
}
);
}
res.end();
});
});
};```

Try this, I guess it might help you.
app.post("/addEvent", (req, res, next) => {
const event = req.body.event;
console.log(req.user.id);
console.log(event);
User.findById({ req.user.id }, async function(err, user) {
if (err) {
console.log(err);
return next(err);
}
if (user) {
User.updateOne(
{
_id: req.user.id
},
{
$push: { events: event }
}
);
}
res.end();
});
});
};
I also recommended you using findByIdAndUpdate or findOneAndUpdate with necessary options in your case. Or findOne instead of find because find returns you [array] of documents, instead of one document, so if you'll be using async/await like that:
const docs = Users.find(query,callback)
They only way to access necessary document will be docs[n] where n is number of doc in resulting array.

Using Multiple FindOne in Mongodb

I am trying to extend the amount of fields that our API is returning. Right now the API is returning the student info by using find, as well as adding some information of the projects by getting the student info and using findOne to get the info about the project that the student is currently registered to.
I am trying to add some information about the course by using the same logic that I used to get the project information.
So I used the same findOne function that I was using for Projects and my logic is the following.
I created a variable where I can save the courseID and then I will put the contents of that variable in the temp object that sending in a json file.
If I comment out the what I added, the code works perfectly and it returns all the students that I require. However, when I make the additional findOne to get information about the course, it stops returning anything but "{}"
I am going to put a comment on the lines of code that I added, to make it easier to find.
Any sort of help will be highly appreciated!
User.find({
isEnrolled: true,
course: {
$ne: null
}
},
'email pantherID firstName lastName project course',
function(err, users) {
console.log("err, users", err, users);
if (err) {
return res.send(err);
} else if (users) {
var userPromises = [];
users.map(function(user) {
userPromises.push(new Promise(function(resolve, reject) {
///////// Added Code START///////
var courseID;
Course.findOne({
fullName: user.course
}, function(err, course) {
console.log("err, course", err, course);
if (err) {
reject('')
}
courseID = course ? course._id : null
//console.log(tempObj)
resolve(tempObj)
}),
///// ADDED CODE END //////
Project.findOne({
title: user.project
}, function(err, proj) {
console.log("err, proj", err, proj);
if (err) {
reject('')
}
//Course ID, Semester, Semester ID
//map to custom object for MJ
var tempObj = {
email: user.email,
id: user.pantherID,
firstName: user.firstName,
lastName: user.lastName,
middle: null,
valid: true,
projectTitle: user.project,
projectId: proj ? proj._id : null,
course: user.course,
courseId: courseID
}
//console.log(tempObj)
resolve(tempObj)
})
}))
})
//async wait and set
Promise.all(userPromises).then(function(results) {
res.json(results)
}).catch(function(err) {
res.send(err)
})
}
})

using promise could be bit tedious, try using async, this is how i would have done it.
// Make sure User, Course & Project models are required.
const async = require('async');
let getUsers = (cb) => {
Users.find({
isEnrolled: true,
course: {
$ne: null
}
}, 'email pantherID firstName lastName project course', (err, users) => {
if (!err) {
cb(null, users);
} else {
cb(err);
}
});
};
let findCourse = (users, cb) => {
async.each(users, (user, ecb) => {
Project.findOne({title: user.project})
.exec((err, project) => {
if (!err) {
users[users.indexOf(user)].projectId = project._id;
ecb();
} else {
ecb(err);
}
});
}, (err) => {
if (!err) {
cb(null, users);
} else {
cb(err);
}
});
};
let findProject = (users, cb) => {
async.each(users, (user, ecb) => {
Course.findOne({fullName: user.course})
.exec((err, course) => {
if (!err) {
users[users.indexOf(user)].courseId = course._id;
ecb();
} else {
ecb(err);
}
});
}, (err) => {
if (!err) {
cb(null, users);
} else {
cb(err);
}
});
};
// This part of the code belongs at the route scope
async.waterfall([
getUsers,
findCourse,
findProject
], (err, result) => {
if (!err) {
res.send(result);
} else {
return res.send(err);
}
});
Hope this gives better insight on how you could go about with multiple IO transactions on the same request.

Mongoose not saving an updated document to the database

EDIT: This question was asked earlier, but I didn't do a good job of asking it. I've rewritten the question. Thanks in advance for your help!
I'm in the process of writing a simple messaging server for a school project. Among its other functionalities, the server allows the user to update the information stored in their account. When the user does update their account, an authentication token is generated for them. Here's the schema that defines all of that. Note, header and body are parts of the user input:
UserSchema = new Schema({
_id: {type: ObjectId, select: false},
username: {type: String, required: true, index: {unique: true} },
password: {type: String, required: true, select: false},
email: {type: String},
token: {type: String, select: false}
}, {
autoIndex: false
});
UserSchema.pre("save", function(next) {
// Create a new token for the user
var self = this;
bcrypt.genSalt(SALT_WORK_FACTOR, function(err, salt) {
if (err) {
next(err);
} else {
crypto.randomBytes(256, function(err, bytes) {
if (err) {
next(err);
} else {
bytes = bytes.toString("hex");
bcrypt.hash((new Date() + bytes), salt, function(err, tokenHash) {
if (err) {
next(err);
} else {
self.token = tokenHash;
next();
}
});
}
});
}
});
});
UserSchema.pre("save", function(next) {
// Hash the password before saving
var self = this;
if (!self.isModified("password")) {
next();
} else {
bcrypt.genSalt(SALT_WORK_FACTOR, function(err, salt) {
if (err) {
next(err);
} else {
bcrypt.hash(self.password, salt, function(err, passwordHash) {
if (err) {
next(err);
} else {
self.password = passwordHash;
next();
}
});
}
});
}
});
I'm running into an issue when updating a particular user. Because I want to use the Model middleware, the way I'm updating a user is by using Model#findOne() followed by Model#save(). Here's the code I have to do that:
// Make sure user provided all necessary information.
if (!header.token) {
return callback(new errors.MissingHeaderDataError("Missing 'token' parameter in the header."));
} else {
// Update the user account based on what's in the envelope's body.
User.findOne({"token": header.token}, "+token +password", function (err, user) {
if (err) {
return callback(err);
} else {
// Get a list of all parameters the user wants to change.
var paramsToChange = Object.keys(body);
// Now update the parameters
paramsToChange.forEach(function(param) {
user[param] = body[param];
});
console.log("Updated user:");
console.dir(user);
user.save(function(err, user) {
if (err) {
return callback(err);
} else {
console.log("Returned user:");
console.dir(user);
User.find({}, "+token +password", function(err, foundUser) {
if (err) {
throw err;
} else {
console.log(JSON.stringify(foundUser));
}
});
callback(null, new SuccessEnvelope(user));
}
});
}
});
}
When I run my tests and come to the last bit of code (after save() is returned), I get this output:
Updated user:
{ token: '$2a$10$5VWWqjJ52aGbS4xc6NDKjuGPv8brX7pRmwiKyYjP8VHoTKCtYZiTu',
username: 'jim_bob',
password: '$2a$10$ue08HUsunzzzcbZURzXF7uaH1dZxF3SwkwadC6D1JsIC9xAUhTbCC',
email: 'joe_bob#email.com',
__v: 0 }
Returned user:
{ token: '$2a$10$fRwED..7fFFhN46Vn.ZJW..xYql5t5P39LHddjFS4kl/pmhwfT.tO',
username: 'jim_bob',
password: '$2a$10$ue08HUsunzzzcbZURzXF7uaH1dZxF3SwkwadC6D1JsIC9xAUhTbCC',
email: 'joe_bob#email.com',
__v: 0 }
[{"token":"$2a$10$5VWWqjJ52aGbS4xc6NDKjuGPv8brX7pRmwiKyYjP8VHoTKCtYZiTu","username":"joe_bob","password":"$2a$10$ue08HUsunzzzcbZURzXF7uaH1dZ
xF3SwkwadC6D1JsIC9xAUhTbCC","email":"joe_bob#email.com","__v":0}]
As you can see, the document is not properly saved to the database, as the previous data is still there. My question is: why? Why is the user not being updated when calling save? I think I'm doing everything properly, but obviously I'm not. Any help with this would be great since I'm going mad!

Apparently, in order to save a document to the database, it needs an _id. Kinda silly that Mongoose doesn't give an error when it doesn't find a document. Alas...
I updated my code to reflect the change:
// Make sure user provided all necessary information.
if (!header.token) {
return callback(new errors.MissingHeaderDataError("Missing 'token' parameter in the header."));
} else {
// Update the user account based on what's in the envelope's body.
User.findOne({"token": header.token}, "+_id +token +password", function (err, user) {
if (err) {
return callback(err);
} else {
console.log("Found user:");
console.dir(user);
// Get a list of all parameters the user wants to change.
var paramsToChange = Object.keys(body);
// Now update the parameters
paramsToChange.forEach(function(param) {
user[param] = body[param];
});
console.log("Updated user:");
console.dir(user);
user.save(function(err, user, numberTouched) {
if (err) {
return callback(err);
} else {
console.log("Returned user:");
console.dir(user);
console.log(numberTouched);
User.find({}, "+token +password", function(err, foundUser) {
if (err) {
throw err;
} else {
console.dir(foundUser);
}
});
callback(null, new SuccessEnvelope(user));
}
});
}
});
}

Mongoose: Find, modify, save

I have a Mongoose User model:
var User = mongoose.model('Users',
mongoose.Schema({
username: 'string',
password: 'string',
rights: 'string'
})
);
I want to find one instance of the User model, modify it's properties, and save the changes. This is what I have tried (it's wrong!):
User.find({username: oldUsername}, function (err, user) {
user.username = newUser.username;
user.password = newUser.password;
user.rights = newUser.rights;
user.save(function (err) {
if(err) {
console.error('ERROR!');
}
});
});
What is the syntax to find, modify and save an instance of the User model?

The user parameter of your callback is an array with find. Use findOne instead of find when querying for a single instance.
User.findOne({username: oldUsername}, function (err, user) {
user.username = newUser.username;
user.password = newUser.password;
user.rights = newUser.rights;
user.save(function (err) {
if(err) {
console.error('ERROR!');
}
});
});

Why not use Model.update? After all you're not using the found user for anything else than to update it's properties:
User.update({username: oldUsername}, {
username: newUser.username,
password: newUser.password,
rights: newUser.rights
}, function(err, numberAffected, rawResponse) {
//handle it
})

findOne, modify fields & save
User.findOne({username: oldUsername})
.then(user => {
user.username = newUser.username;
user.password = newUser.password;
user.rights = newUser.rights;
user.markModified('username');
user.markModified('password');
user.markModified('rights');
user.save(err => console.log(err));
});
OR findOneAndUpdate
User.findOneAndUpdate({username: oldUsername}, {$set: { username: newUser.username, user: newUser.password, user:newUser.rights;}}, {new: true}, (err, doc) => {
if (err) {
console.log("Something wrong when updating data!");
}
console.log(doc);
});
Also see updateOne

I wanted to add something very important. I use JohnnyHK method a lot but I noticed sometimes the changes didn't persist to the database. When I used .markModified it worked.
User.findOne({username: oldUsername}, function (err, user) {
user.username = newUser.username;
user.password = newUser.password;
user.rights = newUser.rights;
user.markModified(username)
user.markModified(password)
user.markModified(rights)
user.save(function (err) {
if(err) {
console.error('ERROR!');
}
});
});
tell mongoose about the change with doc.markModified('pathToYourDate') before saving.

If you want to use find, like I would for any validation you want to do on the client side.
find returns an ARRAY of objects
findOne returns only an object
Adding user = user[0] made the save method work for me.
Here is where you put it.
User.find({username: oldUsername}, function (err, user) {
user = user[0];
user.username = newUser.username;
user.password = newUser.password;
user.rights = newUser.rights;
user.save(function (err) {
if(err) {
console.error('ERROR!');
}
});
});

You could also write it a little more cleaner using updateOne & $set, plus async/await.
const updateUser = async (newUser) => {
try {
await User.updateOne({ username: oldUsername }, {
$set: {
username: newUser.username,
password: newUser.password,
rights: newUser.rights
}
})
} catch (err) {
console.log(err)
}
}
Since you don't need the resulting document, you can just use updateOne instead of findOneAndUpdate.
Here's a good discussion about the difference: MongoDB 3.2 - Use cases for updateOne over findOneAndUpdate