MongoError: E11000 duplicate key error collection with passport

Question

I have the following userSchema

var mongoose = require("mongoose"),
passportLocalMongoose = require("passport-local-mongoose");

var userSchema = new mongoose.Schema({
email: String,
password: String,
userName: String,
fname: String,
lname: String,
userType: Number,
subscribedThreads: [
    {
        type: mongoose.Schema.Types.ObjectId,
        ref: "Threads"
    }
]
});
// add passport methods
userSchema.plugin(passportLocalMongoose);
// export modules to be used by the file requiring it
module.exports = mongoose.model("Users",userSchema);

The first entry into the collection occurs as it should but the next ones give

{ [MongoError: E11000 duplicate key error collection: KManV3.users 
index: username_1 dup key: { : null }]
name: 'MongoError',
message: 'E11000 duplicate key error collection: KManV3.users index: 
username_1 dup key: { : null }',
driver: true,
code: 11000,
index: 0,
errmsg: 'E11000 duplicate key error collection: KManV3.users index: 
username_1 dup key: { : null }',
getOperation: [Function],
toJSON: [Function],
toString: [Function] 
}

Also, dbname.users.getIndexes() gives:

> db.users.getIndexes()
[
{
    "v" : 1,
    "key" : {
        "_id" : 1
    },
    "name" : "_id_",
    "ns" : "KManV3.users"
},
{
    "v" : 1,
    "key" : {
        "password" : 1
    },
    "name" : "password_1",
    "ns" : "KManV3.users",
    "background" : true
},
{
    "v" : 1,
    "unique" : true,
    "key" : {
        "username" : 1
    },
    "name" : "username_1",
    "ns" : "KManV3.users",
    "background" : true
}
]

Apparently every property of schema has been set as unique and I can't add data into collections even if the data is totally different. I'm not sure if it's due to integration of passport.

Answer 1

Looking at the options for passport-local-mongoose:

usernameField: specifies the field name that holds the username. Defaults to 'username'.

usernameUnique : specifies if the username field should be enforced to be unique by a mongodb index or not. Defaults to true.

Which explains why your collection has a unique index on the (non-existent-in-your-schema) username field.

If you don't actually set this field in documents that you add to the database, MongoDB will use null, and once the first document has been inserted, a subsequent document (also with the field value null for username) will throw an E11000 error.

So first, remove the index on username (and also password, I assume you once marked that field as unique in your schema), and set the proper field name for passport-local-mongoose to use:

userSchema.plugin(passportLocalMongoose, { usernameField : 'userName' });

(or email, if you want that field to be used as unique user identifier)