Checklist to be followed for Loopback Migration to v3.

LoopBack-Migration-Checklist.md

Reference: https://loopback.io/doc/en/lb3/Migrating-to-3.0.html

PR: freeCodeCamp/freeCodeCamp#15892

Checklist for Upgrade:

• Update LoopBack version

  • Edit package.json
  • Update dependencies with npm

• Update use of REST error handler

• Replace LoopBack middleware “getter” properties NOT Required or Already in Compliance

• Update models

  • Change use of PUT endpoints NOT Required or Already in Compliance
  • Remove use of undefined mixins NOT Required or Already in Compliance
  • Update remote method definitions
  • Remove dots from model property names
  • Rename models called “File” NOT Required or Already in Compliance

• Update models derived from PersistedModel

  • Use forceId to explicitly set model IDs NOT Required or Already in Compliance
  • Revise use of PersistedModel.create() NOT Required or Already in Compliance
  • Remove check for ctx.instance in “loaded” operation hooks NOT Required or Already in Compliance
  • Replace removed PersistedModel event listeners NOT Required or Already in Compliance
  • Replace calls to PersistedModel.updateOrCreate() with array argument NOT Required or Already in Compliance

• Explicitly add User model properties that were removed NOT Required or Already in Compliance

• Check request parameter encoding

• Remove use of current-context methods, middleware, and configuration settings

  • note this throws errors like so:

  Error: Unknown "flyer" id "undefined".
    at Function.convertNullToNotFoundError (/Users/raisedadead/DEV/freeCodeCamp/node_modules/loopback/lib/persisted-model.js:89:17)
    at invokeRestAfter (/Users/raisedadead/DEV/freeCodeCamp/node_modules/strong-remoting/lib/rest-adapter.js:472:25)
    at /Users/raisedadead/DEV/freeCodeCamp/node_modules/async/dist/async.js:3686:9
    at replenish (/Users/raisedadead/DEV/freeCodeCamp/node_modules/async/dist/async.js:881:17)
    at iterateeCallback (/Users/raisedadead/DEV/freeCodeCamp/node_modules/async/dist/async.js:866:17)
    at /Users/raisedadead/DEV/freeCodeCamp/node_modules/async/dist/async.js:843:16
    at /Users/raisedadead/DEV/freeCodeCamp/node_modules/async/dist/async.js:3691:13
    at apply (/Users/raisedadead/DEV/freeCodeCamp/node_modules/async/dist/async.js:21:25)
    at /Users/raisedadead/DEV/freeCodeCamp/node_modules/async/dist/async.js:56:12
    at interceptInvocationErrors (/Users/raisedadead/DEV/freeCodeCamp/node_modules/strong-remoting/lib/remote-objects.js:685:22)
    at /Users/raisedadead/DEV/freeCodeCamp/node_modules/strong-remoting/node_modules/loopback-phase/node_modules/async/lib/async.js:154:25
    at /Users/raisedadead/DEV/freeCodeCamp/node_modules/strong-remoting/node_modules/loopback-phase/node_modules/async/lib/async.js:154:25
    at /Users/raisedadead/DEV/freeCodeCamp/node_modules/strong-remoting/node_modules/loopback-phase/node_modules/async/lib/async.js:154:25
    at execStack (/Users/raisedadead/DEV/freeCodeCamp/node_modules/strong-remoting/lib/remote-objects.js:494:7)
    at RemoteObjects.execHooks (/Users/raisedadead/DEV/freeCodeCamp/node_modules/strong-remoting/lib/remote-objects.js:498:10)
    at phaseAfterInvoke (/Users/raisedadead/DEV/freeCodeCamp/node_modules/strong-remoting/lib/remote-objects.js:656:10)

• Update use of promises Fixed by freeCodeCamp/freeCodeCamp#15628

• Check CORS configuration

There is an exception thrown when we try and send a welcome email, but I have also checked that this is easily resolved by: freeCodeCamp/freeCodeCamp#9660

Update:
Thanks to @BerkeleyTrue it's now known that this was due to LB's implementation of promises. And this is now fixed by:
freeCodeCamp/freeCodeCamp#15628