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Migrating from v1.x to 2.x

Migrating from v1.x to 2.x brings with it a few changes to be aware of.


Previously the auto_reconnect option of the node-mongodb-driver defaulted to false. It now defaults to true so if your connection drops while your app is running the driver will continue retrying until it can connect again.

Private props

Several internal instance props have had name changes so its more obvious that they are not intended for public use. Namely instance.doc has changed to instance._doc since it contains the structure Mongoose relies on to operate properly and should only be manipulated with caution.

Here are the relavent changes:

var thing = new Thing;

thing.doc             -> thing._doc
thing.activePaths     -> thing._activePaths
thing.saveError       -> thing._saveError
thing.validationError -> thing._validationError

Circular refs in getters

Previously Mongoose exibited very odd behavior with getters:

toy.color.color.color.color ... // actually worked!

Obviously this was wrong and has now been fixed.

toy.color.color // undefined

Getter / Setter scope

Nested getter/setter scopes were set incorrectly since version 1.7 or so. This has been fixed. In your getter/setter, this now properly refers to the instance.

var SongSchema = new Schema({
    title: String
  , detail: {
        format: String

SongSchema.path('detail.format').get(function () {
  console.log(this !== this.detail) // true, used to be false

You may not have noticed this bug since the circular getters previously masked (mostly) this bad behavior.

Setters application

Setters are no longer applied when the doc returns from the db (bug). It caused problems for folks trying to use setters for passwords / salts resulting in doubly hashed passwords after queries.

UserSchema.path('password').set(function (val) {
  // now only runs when you change `user.password`
  // not when the doc returns from the db


If you were using the Query object directly and calling its bind method, the v1.x behavior cloned the query and returned the new one. This is no longer the case. The query is now simply bound and returns itself.

Multiple collection support removed

In 1.x Mongoose had support for multiple collection names per model. This was an edge case and support for it has been removed.

Compat.js removed

Backward compatibility with verions 0.x has been removed.

require('mongoose').compat = true // no longer does anything

Utils.erase removed

We removed utils.erase since it was unused in the project. If you were using it you'll need to copy it from the 1.x branch into your own.

Error handling

Previously, the error returned after failed validation contained an errors object which was a hash of path keys to error message values. Now the Error returned is more helpful. Instead of the errors object containing string values it holds the actual ValidatorError. Each ValidatorError has a type and path property providing us with a little more error handling flexibility.

var ToySchema = new Schema({
    color: String
  , name: String

var Toy = db.model('Toy', ToySchema);

Toy.schema.path('name').validate(function (value) {
  return /blue|green|white|red|orange|periwinkel/i.test(value);
}, 'Invalid color');

var toy = new Toy({ color: 'grease'}); (err) {
  // previous behavior (v1x):

  // prints 'Validator "Invalid color" failed for path color'

  // new v2x behavior - err.errors.color is a ValidatorError object

  // prints 'Validator "Invalid color" failed for path color'

  // you can get v1 behavior back by casting error.color toString

  // prints 'Validator "Invalid color" failed for path color'

  // prints "Invalid color"

  // prints "color"

  // prints "ValidationError"

  // prints "Validation failed"

BTW, the err.errors object is also available on the model instance.

toy.errors.color.message === err.errors.color.message