MongoError: E11000 duplicate key error collection: tracker-db.users index: username_1 dup key: { username: null }"

Question

A bunch of similar questions answered before but none of them seem to fix my problem. No problem in adding the first user. However, the username doesn't display the records and gives error on adding the second user.

const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const userSchema = new Schema(
    {
        username: {
            type: String,
            unique: true,
            required: true,
            minlength: 3,
        },
        gender: String,
        age: Number
    },
    {
        timestamps: true
    }
);

const User = mongoose.model('user', userSchema);
module.exports = User;

The error that I'm getting

The record on adding first user

Byway

Please check whether the user document that you are saving has a not null username. I think during the first and second time username is passed as null to the database. – Interpolate

Yes, thats what is happening, but how do I change that? Any suggestions – Byway

Can you add the code that is actually using the model to save the user? It looks like it is not using the required: true, if it is saving without a username – Piton

For me , this error came because I wasn't sending a response on successful operation. – Ebonyeboracum

Answer 1

---

ONLY FOR TEST DTABASE

---

Simply drop the collection and make the request again . This should work just fine.

Stites

do you know why this error happens? also your solution worked!! – Aube

Imagine this happening in a prod env and the solution is to drop the collection wtf – Nels

same thoughts @JorgeDiaz, this dropping of collection is not the real answer to solution – Jegar

open to mongoDB Compass → database from left → open the desired collection → select indexes tab and remove the entry that is causing the issue. – Matrices

Answer 2

Deleting the collection and recreating the collection in mongodb worked for me

Protozoon

not the idea solution, imagine this is on production level – Jegar

Answer 3

In Robo3T I had to look up my collections indexes, and manually delete the username index.

Dashtilut

Answer 4

add a username to your schema, i had the same problem and i did this

function(accessToken, refreshToken, profile, cb) { console.log(profile); User.findOrCreate({ username: profile.displayName, googleId: profile.id }, function (err, user) { return cb(err, user); }); i simply added a username in my findorcreate function so that it does not show username null

Iene

Answer 5

Your collection has a extra index named username_1 which is causing this error. When you already have 1 document in your collection with that parameter (username_1) as null, mongodb does not allow to add one more document after that with the same paramter as null (which you are doing without knowing).

How to fix it? You need to delete the index named username_1 from your collection. If you are using MongoDBCompass, go to Indexes and delete the index named username_1.

Scrivings

Answer 6

dropping the collection from Mongo DB worked for me, but can anyone explain this

Antrim

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center. – Dada

Answer 7

Try this out, I wish it will be helpful.

Creating a new Database in MongoDB server and saving the data in that new location, worked for me :-)

Caneghem

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center. – Dada

Answer 8

the problem is not in this module you presented here.

We need to see your code from your.js file assuming you are using express and body-parser to make all this work. I think and i made a little trial of your app and i can tell that your REQ POST using POSTMAN is incorrect. WHY ? Because you are sending a POST REQ to

   http://localhost:3000/users/add

   and you are setting PARAMS with username: randomguy
   and that's why you're getting that error from MongoDB 
   {username: null}. 

To fix this issue in POSTMAN you must leave PARAMS EMPTY (REMOVE ALL KEY/VALUE FIELDS) and instead make the POST request including KEY/VALUE in BODY Field:

   username: randomGuy

In my case i'm using body-parser like this:

   app.use(bodyParser.urlencoded({ extended: true }));

and in POSTMAN in BODY select the radiobutton x-www-form-urlencoded

/PARAMS is used for GET req/

POSTMAN POST REQ TO local MongoDB with BODY KEY/VALUE

Worcestershire

Answer 9

Thank you @alps solved my issue here is copy paste for beginners: add username: profile.displayName in my User.findorcreate function for reference:

For Google:

function(accessToken, refreshToken, profile, cb) {
    console.log(profile);
    User.findOrCreate({ username: profile.displayName, googleId: profile.id }, function (err, user) { 
     return cb(err, user) 
    });
}

For Facebook:

function(accessToken, refreshToken, profile, cb) {
    console.log(profile);
    User.findOrCreate({ username: profile.displayName, facebookId: profile.id }, function (err, user) {
      return cb(err, user);
    });
}

Elmaelmajian

Answer 10

Delete all the indexes on database once and try again, I am sure this will work

Tope

Answer 11

It's possible that you set the username to be unique in your model and must have likely created the initial document in your collection.

To solve the problem, navigate to the index in your collection and delete the username.

It should work

Jabalpur

Answer 12

If you're using MongoDB. Delete your database using Mongo Compass or using terminal.. Thats works for me.

Extremity

Answer 13

It helps to drop the database once which you are using, then restart the server again...

1. show dbs
2. use myDatabase // the one which you want to remove, i.e. replace "myDatabase" accordingly
3. db.dropDatabase()
4. show dbs() // run your server again then problem will be solved.

Unconventionality

Answer 14

Just Go In mongodb Database Section and Delete the Indexes named user_id user_id1 marked as the unique indexes in db ,

Quinta