nodejs仅能在数据库中创建一个用户

Question

I'm using an api route in nodejs to add a user to the database with mongoose. Standard stuff. However, it works perfectly with one user. Then when I try to create another user the new user is logged in but not saved to the database.

Any help is appreciated. Here is the route code:

    app.get('/register' , function(req , res) {
    res.sendFile(path.join(__dirname , '../public' , 'register.html'));
});
app.post('/api/register' , function(req, res) {
    User.findOne({'local.email': req.body.email}, function(err, user) {
        if(err) {
            return res.json({
                'message': err
            });
        }
        if(user) {
            return res.json({
                'message': 'User already exists'
            });
        } else {
            let newUser = new User();

            newUser.local.email = req.body.email;
            newUser.local.name = req.body.name;
            newUser.local.password = newUser.setPassword(req.body.password);

            newUser.save(function(err) {
                var token;
                token = newUser.generateJwt();
                res.status(200);
                res.json({
                    'token': token
                });
            });
        }
    });
});

Schema:

const bcrypt = require('bcrypt-nodejs');
const jwt = require('jsonwebtoken');
const mongoose = require('mongoose');
let userSchema = new mongoose.Schema({
    local: {
        email: String,
        name: String,
        password: String
    }
});
userSchema.methods.setPassword = function(password) {
    return bcrypt.hashSync(password, bcrypt.genSaltSync(10), null);
}
userSchema.methods.validatePassword = function(password) {
    return bcrypt.compareSync(password, this.local.password);
}
userSchema.methods.generateJwt = function() {
  var expire = new Date();
  expire.setDate(expire.getDate() + 7);

  return jwt.sign({
    _id: this._id,
    email: this.local.email,
    name: this.local.name,
    exp: parseInt(expire.getTime() / 1000),
  }, process.env.CONFIG_SR);
};
module.exports = mongoose.model('User' , userSchema);

Answer 1

let allows you to declare variables that are limited in scope to the block, statement, or expression on which it is used. This is unlike the var keyword, which defines a variable globally, or locally to an entire function regardless of block scope.

let newUser = new User(); 

change this to

var newUser = new User():

Answer 2

Turns out this was an issue with mLab. To fix it, I deleted the users collection and registered a new user. After the users collection was generated again, I was able to add new users to the database.