Mongoose Schema hasn't been registered for model

Question

I\'m learning the mean stack and when I try to start the server using

npm start

I get an exception saying that:

schema has         


        

Answer 1

IF YOU USE MULTIPLE mongoDB CONNECTIONS

---

beware that when using .populate() you MUST provide the model as mongoose will only "find" models on the same connection. ie where:

var db1 = mongoose.createConnection('mongodb://localhost:27017/gh3639');
var db2 = mongoose.createConnection('mongodb://localhost:27017/gh3639_2');
var userSchema = mongoose.Schema({
  "name": String,
  "email": String
});

var customerSchema = mongoose.Schema({
  "name" : { type: String },
  "email" : [ String ],
  "created_by" : { type: mongoose.Schema.Types.ObjectId, ref: 'users' },
});

var User = db1.model('users', userSchema);
var Customer = db2.model('customers', customerSchema);

Correct:

Customer.findOne({}).populate('created_by', 'name email', User)

or

Customer.findOne({}).populate({ path: 'created_by', model: User })

Incorrect (produces "schema hasn't been registered for model" error):

Customer.findOne({}).populate('created_by');