mongoose : Discriminator with name " " already exists

Question

I'm using mongoose to interact with mongoDB in a rest API, and while using discriminators, I get this error :

Discriminator with name "serviceMember" already exists

know that with this code everything is fine :

const serviceManagerSchema = new Schema({
    serviceId : {
    	type : Schema.Types.ObjectId,
    	ref : 'service'
    },
    serviceMembers : [{
    	type : Schema.Types.ObjectId,
    	ref : 'serviceMember'
    }] 
},options)

const ServiceManager = Employee.discriminator('serviceManager',serviceManagerSchema)

but this doesn't work

const serviceMemberSchema = new Schema({
 
 },options)

const ServiceMember = Employee.discriminator('serviceMember',serviceMemberSchema)

module.exports = ServiceMember

I have tried to replace the "serviceMember" name with another name that i'm sure i have never used it, but still the same error

Help me please, thank you in advance

Answer 1

I know this question has cobwebs on it, but in case anyone else ever comes here looking for a solution to this problem here's how I solved it. In my case I was getting this error due to using Mongoose with Next.js - everytime Next hot reloaded my model module (in my case, the base model is called 'User'), all of the discriminators would collide.

To solve the issue, I had to delete the discriminator model (because Mongoose creates a full-fledged model for each discriminator) and then also delete the discriminator from the User model:

// Patient handler
if (mongoose.modelNames().includes('patient')) {
  log.trace('Deleting patient model');
  mongoose.deleteModel('patient');
}

if (User.discriminators && 'patient' in User.discriminators) {
  log.trace('Deleting patient discriminator');
  delete User.discriminators.patient;
}

const Patient = User.discriminator(
  'patient',
  new mongoose.Schema(
    {
      healthCard: { type: String, unique: true },
      homePhone: { type: String },
      birthDate: { type: Date, required: true },
    },
    options
  )
);