MongoDB and Mongoose - Create a Model Error : 'modelName' of undefined

MongoDB and Mongoose - Create a Model Error : 'modelName' of undefined


Challenge Link :
error : Cannot read property ‘modelName’ of undefined

Server.js :

var Schema = mongoose.Schema;
var personSchema = new Schema({
   name: {type: String, required: true},
   age: Number,
   favoriteFoods: [String]

var Person = mongoose.model('Person', personSchema);

Please note :
i also tried adding the below code later but no succcess (and is this even required ?)

Person.create({ name: 'Teste', age: 18, favoriteFoods: ['Pao','Hamburger'] }, function (error, result) 
            if(error) return result.end(error);


Check your package.json to make sure you are including mongoose in your dependencies. And then, at the top of your server.js, make sure you have
const mongoose = require('mongoose')


yes @warpfox, did that already, anything else ?


Can you show the code containing the implementation of ‘modelName’?

Disregard this. It’s handled in the server.js file.


The error is likely coming from here (server.js file, which should NOT be edited):

if(req.method !== 'OPTIONS' && Person.modelName !== 'Person')

The server.js file requires the person model in this way:

var Person = require('./myApp.js').PersonModel;

and gets it from myApp.js in this way (from the myApp.js file):

exports.PersonModel = Person;

Now, in your post, you’ve stated that you’re giving code from the ‘server.js file’, which you shouldn’t be editing. Was this a mistake, or are you directly editing ‘server.js’ instead of ‘myApp.js’? If so, this seems to be the problem.


I havent created a myApp.js file as i dont know what to put in it, can u please tell me how will myApp.js go about ?


In your Glitch project, in the file manager on the left side of the screen, is there no file called ‘myApp.js’? If not, you could create the file ‘myApp.js’ using ‘+ New File’ and then paste in the following code (don’t put it in the ‘public’ folder, though):

* 3. FCC Mongo & Mongoose Challenges
* ==================================

/*  ================== */

/** 1) Install & Set up mongoose */

// Add `mongodb` and `mongoose` to the project's `package.json`. Then require 
// `mongoose`. Store your **mLab** database URI in the private `.env` file 
// as `MONGO_URI`. Connect to the database using `mongoose.connect(<Your URI>)`

/** # SCHEMAS and MODELS #
/*  ====================== */

/** 2) Create a 'Person' Model */

// First of all we need a **Schema**. Each schema maps to a MongoDB collection
// and defines the shape of the documents within that collection. Schemas are
// building block for Models. They can be nested to create complex models,
// but in this case we'll keep things simple. A model allows you to create
// instances of your objects, called **documents**.

// Create a person having this prototype :

// - Person Prototype -
// --------------------
// name : string [required]
// age :  number
// favoriteFoods : array of strings (*)

// Use the mongoose basic *schema types*. If you want you can also add more
// fields, use simple validators like `required` or `unique`, and set
// `default` values. See the [mongoose docs](

// <Your code here >

var Person /* = <Your Model> */

// **Note**: GoMix is a real server, and in real servers interactions with
// the db are placed in handler functions, to be called when some event happens
// (e.g. someone hits an endpoint on your API). We'll follow the same approach
// in these exercises. The `done()` function is a callback that tells us that
// we can proceed after completing an asynchronous operation such as inserting,
// searching, updating or deleting. It's following the Node convention and
// should be called as `done(null, data)` on success, or `done(err)` on error.
// **Warning** - When interacting with remote services, **errors may occur** !

// - Example -
// var someFunc = function(done) {
//   ... do something (risky) ...
//   if(error) return done(error);
//   done(null, result);
// };

/** # [C]RUD part I - CREATE #
/*  ========================== */

/** 3) Create and Save a Person */

// Create a `document` instance using the `Person` constructor you build before.
// Pass to the constructor an object having the fields `name`, `age`,
// and `favoriteFoods`. Their types must be conformant to the ones in
// the Person `Schema`. Then call the method `` on the returned
// document instance, passing to it a callback using the Node convention.
// This is a common pattern, all the **CRUD** methods take a callback 
// function like this as the last argument.

// - Example -
// ...
//, data) {
// your stuff here...
// });

var createAndSavePerson = function(done) {
  done(null /*, data*/);


/** 4) Create many People with `Model.create()` */

// Sometimes you need to create many Instances of your Models,
// e.g. when seeding a database with initial data. `Model.create()`
// takes an array of objects like [{name: 'John', ...}, {...}, ...],
// as the 1st argument, and saves them all in the db.
// Create many people using `Model.create()`, using the function argument
// 'arrayOfPeople'.

var createManyPeople = function(arrayOfPeople, done) {
    done(null/*, data*/);

/** # C[R]UD part II - READ #
/*  ========================= */

/** 5) Use `Model.find()` */

// Find all the people having a given name, using `Model.find() -> [Person]`
// In its simplest usage, `Model.find()` accepts a **query** document (a JSON
// object ) as the first argument, and returns an **array** of matches.
// It supports an extremely wide range of search options. Check it in the docs.
// Use the function argument `personName` as search key.

var findPeopleByName = function(personName, done) {
  done(null/*, data*/);


/** 6) Use `Model.findOne()` */

// `Model.findOne()` behaves like `.find()`, but it returns **only one**
// document, even if there are more. It is especially useful
// when searching by properties that you have declared as unique.
// Find just one person which has a certain food in her favorites,
// using `Model.findOne() -> Person`. Use the function
// argument `food` as search key

var findOneByFood = function(food, done) {

  done(null/*, data*/);

/** 7) Use `Model.findById()` */

// When saving a document, mongodb automatically add the field `_id`,
// and set it to a unique alphanumeric key. Searching by `_id` is an
// extremely frequent operation, so `moongose` provides a dedicated
// method for it. Find the (only!!) person having a certain Id,
// using `Model.findById() -> Person`.
// Use the function argument 'personId' as search key.

var findPersonById = function(personId, done) {
  done(null/*, data*/);

/** # CR[U]D part III - UPDATE # 
/*  ============================ */

/** 8) Classic Update : Find, Edit then Save */

// In the good old days this was what you needed to do if you wanted to edit
// a document and be able to use it somehow e.g. sending it back in a server
// response. Mongoose has a dedicated updating method : `Model.update()`,
// which is directly binded to the low-level mongo driver.
// It can bulk edit many documents matching certain criteria, but it doesn't
// pass the edited document to its callback, only a 'status' message.
// Furthermore it makes validation difficult, because it just
// direcly calls the mongodb driver.

// Find a person by Id ( use any of the above methods ) with the parameter
// `personId` as search key. Add "hamburger" to the list of her `favoriteFoods`
// (you can use Array.push()). Then - **inside the find callback** - `.save()`
// the updated `Person`.

// [*] Hint: This may be tricky if in your `Schema` you declared
// `favoriteFoods` as an `Array` without specifying the type (i.e. `[String]`).
// In that case `favoriteFoods` defaults to `Mixed` type, and you have to
// manually mark it as edited using `document.markModified('edited-field')`
// ( - #Mixed )

var findEditThenSave = function(personId, done) {
  var foodToAdd = 'hamburger';
  done(null/*, data*/);

/** 9) New Update : Use `findOneAndUpdate()` */

// Recent versions of `mongoose` have methods to simplify documents updating.
// Some more advanced features (i.e. pre/post hooks, validation) beahve
// differently with this approach, so the 'Classic' method is still useful in
// many situations. `findByIdAndUpdate()` can be used when searching by Id.
// Find a person by `name` and set her age to `20`. Use the function parameter
// `personName` as search key.
// Hint: We want you to return the **updated** document. In order to do that
// you need to pass the options document `{ new: true }` as the 3rd argument
// to `findOneAndUpdate()`. By default the method
// passes the unmodified object to its callback.

var findAndUpdate = function(personName, done) {
  var ageToSet = 20;

  done(null/*, data*/);

/** # CRU[D] part IV - DELETE #
/*  =========================== */

/** 10) Delete one Person */

// Delete one person by her `_id`. You should use one of the methods
// `findByIdAndRemove()` or `findOneAndRemove()`. They are similar to the
// previous update methods. They pass the removed document to the cb.
// As usual, use the function argument `personId` as search key.

var removeById = function(personId, done) {
  done(null/*, data*/);

/** 11) Delete many People */

// `Model.remove()` is useful to delete all the documents matching given criteria.
// Delete all the people whose name is "Mary", using `Model.remove()`.
// Pass to it a query ducument with the "name" field set, and of course a callback.
// Note: `Model.remove()` doesn't return the removed document, but a document
// containing the outcome of the operation, and the number of items affected.
// Don't forget to pass it to the `done()` callback, since we use it in tests.

var removeManyPeople = function(done) {
  var nameToRemove = "Mary";

  done(null/*, data*/);

/** # C[R]UD part V -  More about Queries # 
/*  ======================================= */

/** 12) Chain Query helpers */

// If you don't pass the `callback` as the last argument to `Model.find()`
// (or to the other similar search methods introduced before), the query is
// not executed, and can even be stored in a variable for later use.
// This kind of object enables you to build up a query using chaining syntax.
// The actual db search is executed when you finally chain
// the method `.exec()`, passing your callback to it.
// There are many query helpers, here we'll use the most 'famous' ones.

// Find people who like "burrito". Sort them alphabetically by name,
// Limit the results to two documents, and hide their age.
// Chain `.find()`, `.sort()`, `.limit()`, `.select()`, and then `.exec()`,
// passing the `done(err, data)` callback to it.

var queryChain = function(done) {
  var foodToSearch = "burrito";
  done(null/*, data*/);

/** **Well Done !!**
/* You completed these challenges, let's go celebrate !

/** # Further Readings... #
/*  ======================= */
// If you are eager to learn and want to go deeper, You may look at :
// * Indexes ( very important for query efficiency ),
// * Pre/Post hooks,
// * Validation,
// * Schema Virtuals and  Model, Static, and Instance methods,
// * and much more in the [mongoose docs](

//----- **DO NOT EDIT BELOW THIS LINE** ----------------------------------

exports.PersonModel = Person;
exports.createAndSavePerson = createAndSavePerson;
exports.findPeopleByName = findPeopleByName;
exports.findOneByFood = findOneByFood;
exports.findPersonById = findPersonById;
exports.findEditThenSave = findEditThenSave;
exports.findAndUpdate = findAndUpdate;
exports.createManyPeople = createManyPeople;
exports.removeById = removeById;
exports.removeManyPeople = removeManyPeople;
exports.queryChain = queryChain;

If that doesn’t work try doing this exercise again by opening up a new Glitch project from the fCC link on the page titled " Introduction to the MongoDB and Mongoose Challenges"

Maybe even try it in a different browser. Switching from Chrome to Firefox made things different for me just now; in Chrome, the ‘myApp.js’ file was missing and the ‘server.js’ file had only the message ‘This document has been deleted outside of the editor.’ With Firefox, both files were there. I can’t explain why at the moment, though.


Thanks alot, just fitted some stuff here and there and got it !
although 2 doubts

  1. why is the myApp.js not appearing in any browser ? (i tried them all)
  2. i had to add var mongoose = require(‘mongoose’); to both, server.js and myapp.js in order to complete the task, Why ?