# List of notable changes made between 2.x and 3.0

All breaking changes must be described here. When adding a new entry,
always describe the impact on users and instructions for upgrading
applications from 2.x to 3.0.

See also https://github.com/strongloop/loopback/blob/master/3.0-DEVELOPING.md

## Always use bluebird as promise library

In version 3.0, we always use bluebird as our promise library
instead of `global.Promise`.
We consider Bluebird API a part of LoopBack API from now on,
you are welcome to use any Bluebird-specific methods in your applications.

If you are using LoopBack with a custom promise implementation provided
via `global.Promise`,
you will have to check all places where you are using non-standard promise API
and update them to use Bluebird API instead.

Please see [Related code change](https://github.com/strongloop/loopback-datasource-juggler/pull/790) here.

## DAO.find provides ctx.data in "loaded" hook

When implementing "loaded" hook for `DAO.find` method, we have mistakenly
implemented a version that sets `ctx.instance` instead of `ctx.data`. This
defeats the purpose of the "loaded" hook, which is to allow hooks to modify
the raw data provided by the datasource before it's used to build a model
instance.

This has been fixed in 3.0 and the "loaded" hook now consistently provides
`ctx.data` for all operations. If you have a "loaded" hook handler that
checks `if (ctx.instance)` then you can remove this condition together with
the branch that follows.

See also the commit [30283291](https://github.com/strongloop/loopback-datasource-juggler/commit/30283291?w=1)

## DAO.create no longer returns the instance(s) created

While implementing support for promises in `DAO.create`, we found that this
method returns the instance object synchronously. This is inconsistent with
the usual convention of accessing the result via callback/promise and it may
not work correctly in cases where some fields like the `id` property are
generated by the database.

We have changed the API to be consistent with other DAO methods: when invoked
with a callback argument, the method does not return anything. When invoked
without any callback, a promise is returned.

See [pull request 918](https://github.com/strongloop/loopback-datasource-juggler/pull/918)
for more details.