Sign Up not working and throwing params errors

Question

I am currently able to sign in just fine with previously created user credentials and use the app as normal, but am unable to create a new user. I am using React.js on the client side and an Express api on the backend. I am getting a mongoose validation error. All of the authentication came with the template the course has us use and I haven't touched any of those files. I even went back and compared commit history trees to ensure that nothing was changed.

Here is my user schema and sign-up route. I tried eliminating uniqueness from the model and that didn't impact it. I know there is a lot of potential places something could be going wrong, but if anyone has any suggestions on potential issues I would be forever grateful! I console logged the req.body.credentials within sign up and the data being sent over looks good.

Error code: 422 Unprocessable Entity Server side error: 'The received params failed a Mongoose validation'

const mongoose = require('mongoose')
const { petSchema } = require('./pet.js')
const { pictureSchema } = require('./picture.js')

const userSchema = new mongoose.Schema({
  email: {
    type: String,
    required: true,
    unique: true
  },
  hashedPassword: {
    type: String,
    required: true
  },
  token: String,
  pets: [petSchema],
  pictures: [pictureSchema]
}, {
  timestamps: true,
  toObject: {
    // remove `hashedPassword` field when we call `.toObject`
    transform: (_doc, user) => {
      delete user.hashedPassword
      return user
    }
  }
})

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

// SIGN UP
// POST /sign-up
router.post('/sign-up', (req, res) => {
  // start a promise chain, so that any errors will pass to `handle`
  console.log(req.body.credentials)
  Promise.resolve(req.body.credentials)
    // reject any requests where `credentials.password` is not present, or where
    // the password is an empty string
    .then(credentials => {
      if (!credentials ||
          !credentials.password ||
          credentials.password !== credentials.password_confirmation) {
        throw new BadParamsError()
      }
    })
    // generate a hash from the provided password, returning a promise
    .then(() => bcrypt.hash(req.body.credentials.password, bcryptSaltRounds))
    .then(hash => {
      // return necessary params to create a user
      return {
        email: req.body.credentials.email,
        hashedPassword: hash
      }
    })
    // create user with provided email and hashed password
    .then(user => User.create(user))
    // send the new user object back with status 201, but `hashedPassword`
    // won't be sent because of the `transform` in the User model
    .then(user => res.status(201).json({ user: user.toObject() }))
    // pass any errors along to the error handler
    .catch(err => handle(err, res))
})

Answer 1

Solved. One of the subdocuments I had within user had a key with a value set to unique. I needed to eliminate that because my database was indexing users with a null value and throwing a duplicate error. I then needed to reset my database (I just renamed it to test it out) so that it didn't have any saved indexes with that configuration. I just deleted my collections within Heroku as well (luckily I didn't have significant amounts of data in there and this solution was perfectly fine for my situation). I am now able to sign up users again without any duplicate key errors.