What am I doing wrong in this Mongoose unique pre-save validation?

Question

What am I doing wrong in this Mongoose unique pre-save validation?

I'm trying to create a User model, that has an unique username. Here's the code for it:

var mongoose = require("mongoose");

var Schema = mongoose.Schema;

var UserSchema = new Schema({
    username: String,
    password: String,
});

UserSchema.virtual("password_confirmation").get(function() {
    return this.pw_conf;
}).set(function(value) {
    this.pw_conf = value;
});

UserSchema.path("username").required(true);
UserSchema.path("password").required(true);

UserSchema.pre("save",function(next, done) {
    var self = this;
    mongoose.models["User"].findOne({username : self.username},function(err, user) {
        if(user) {
            self.invalidate("user","username must be unique");
        }
        done();
    });
    next();
});

UserSchema.pre("save",function(next) {
    if(this.pw_conf !== this.password) {
        next(new Error("Must specify the password confirmation"));
    }
    else {
        next();
    }
});

module.exports = mongoose.model("User",UserSchema);

I was also testing to see if the uniqueness works:

var User = require("./users"),
  mongoose = require("mongoose");
var u = new User();

mongoose.connect('mongodb://localhost/my_database');

u.username = "me";
u.password = "password";
u.password_confirmation = "password";
u.save(function(err) {
    if(err) {
        console.log(err);
    }
    mongoose.disconnect();
});

Problem is, it doesn't. Each time I run the code, I get a new object created. I am aware that there are probably other ways of ensuring uniqueness, but I'd like to do it in this way. Shouldn't I be calling done after I handle the result of the findOne method? Am I calling next wrong?

javascript
node.js
mongoose

Answer 1

http://mongoosejs.com/docs/api.html#schematype_SchemaType-unique is the way to go. It uses actual MongoDb indexes to make sure that your field is unique. No need for .pre middleware.

Enjoy!

Answer 2

Two possibilities:

Your self.invalidate call should be referencing "username" instead of "user". If that doesn't fix it, you can fail things explicitly by passing an Error object to done if you want to abort the save operation:

UserSchema.pre("save",function(next, done) {
    var self = this;
    mongoose.models["User"].findOne({username : self.username},function(err, user) {
        if(err) {
            done(err);
        } else if(user) {
            self.invalidate("username","username must be unique");
            done(new Error("username must be unique"));
        } else {
            done();
        }
    });
    next();
});

Answer 3

There's a really good plugin for mongoose that's really easy to install and use. The documentation is excellent and it worked for me first time.

But there is an issue with re-saving.

https://npmjs.org/package/mongoose-unique-validator

Answer 4

Have you considered using an asynchronous validator to catch the error?

UserSchema.path('username').validate(function (value, done) {
  User.count({ username: value }, function (error, count) {
    // Return false if an error is thrown or count > 0
    done(!(error || count));
  });
}, 'unique');