E11000 duplicate key error index in mongodb mongoo

Question

Following is my user schema in user.js model -

var userSchema = new mongoose.Schema({
    local: {
        name: { type: String },
        email : { type: String, require: true, unique: true },
        password: { type: String, require:true },
    },
    facebook: {
        id           : { type: String },
        token        : { type: String },
        email        : { type: String },
        name         : { type: String }
    }
});

var User = mongoose.model('User',userSchema);

module.exports = User;

This is how I am using it in my controller -

var user = require('./../models/user.js');

This is how I am saving it in the db -

user({'local.email' : req.body.email, 'local.password' : req.body.password}).save(function(err, result){
    if(err)
        res.send(err);
    else {
        console.log(result);
        req.session.user = result;
        res.send({"code":200,"message":"Record inserted successfully"});
    }
});

Error -

{"name":"MongoError","code":11000,"err":"insertDocument :: caused by :: 11000 E11000 duplicate key error index: mydb.users.$email_1  dup key: { : null }"} 

I checked the db collection and no such duplicate entry exists, let me know what I am doing wrong ?

FYI - req.body.email and req.body.password are fetching values.

I also checked this post but no help STACK LINK

If I removed completely then it inserts the document, otherwise it throws error "Duplicate" error even I have an entry in the local.email

Answer 1

I had the same issue. Tried debugging different ways couldn't figure out. I tried dropping the collection and it worked fine after that. Although this is not a good solution if your collection has many documents. But if you are in the early state of development try dropping the collection.

db.users.drop();

Answer 2

same issue after removing properties from a schema after first building some indexes on saving. removing property from schema leads to an null value for a non existing property, that still had an index. dropping index or starting with a new collection from scratch helps here.

note: the error message will lead you in that case. it has a path, that does not exist anymore. im my case the old path was ...$uuid_1 (this is an index!), but the new one is ....*priv.uuid_1

Answer 3

I had the same issue when i tried to modify the schema defined using mangoose. I think the issue is due to the reason that there are some underlying process done when creating a collection like describing the indices which are hidden from the user(at least in my case).So the best solution i found was to drop the entire collection and start again.

Answer 4

The error message is saying that there's already a record with null as the email. In other words, you already have a user without an email address.

The relevant documentation for this:

If a document does not have a value for the indexed field in a unique index, the index will store a null value for this document. Because of the unique constraint, MongoDB will only permit one document that lacks the indexed field. If there is more than one document without a value for the indexed field or is missing the indexed field, the index build will fail with a duplicate key error.

You can combine the unique constraint with the sparse index to filter these null values from the unique index and avoid the error.

unique indexes

Sparse indexes only contain entries for documents that have the indexed field, even if the index field contains a null value.

In other words, a sparse index is ok with multiple documents all having null values.

sparse indexes

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From comments:

Your error says that the key is named mydb.users.$email_1 which makes me suspect that you have an index on both users.email and users.local.email (The former being old and unused at the moment). Removing a field from a Mongoose model doesn't affect the database. Check with mydb.users.getIndexes() if this is the case and manually remove the unwanted index with mydb.users.dropIndex(<name>).

Answer 5

Change the collection name if it already exists in the database, it will show an error. And if you given any property as unique the same error will occur.