chore: update dependency loopback-datasource-juggler to ^4.21.1

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
loopback-datasource-juggler	dependencies	minor	^4.20.0 -> ^4.21.1
loopback-datasource-juggler	devDependencies	minor	^4.20.0 -> ^4.21.1

---

Release Notes

strongloop/loopback-datasource-juggler

v4.21.1

v4.21.0

Compare Source

==========================

• types: make DataSource.stop compatible with LB4 (Miroslav Bajtoš)

• feat: implement DataSource.stop() (Miroslav Bajtoš)

• Add __parent reference to embedded models (Dimitris Xalatsis)

---

Renovate configuration

📅 Schedule: At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻️ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about these updates again.

---

• If you want to rebase/retry this PR, check this box

---

This PR has been generated by WhiteSource Renovate. View repository job log here.

[bajtos]

Ouch, looks like loopbackio/loopback-datasource-juggler#1835 was not as backwards compatible as I thought 🙈 While I could change juggler's typings to describe the return value of stop method as PromiseOrValue<void>, I feel such description would be incorrect and would make the stop method more difficult to use outside of LB4 life-cycle observer use-cases.

Instead, I decided bite the bullet and update both our CLI template and existing apps to use the new style where start and stop methods are not scaffolded at all.

[hacksparrow]

👍

[bajtos]

@raymondfeng I added the link you suggested, LGTY now?

[raymondfeng]

Ouch, looks like loopbackio/loopback-datasource-juggler#1835 was not as backwards compatible as I thought 🙈 While I could change juggler's typings to describe the return value of stop method as PromiseOrValue, I feel such description would be incorrect and would make the stop method more difficult to use outside of LB4 life-cycle observer use-cases.

What usage is broken do you have in mind?

[bajtos]

What usage is broken do you have in mind?

See the failed CI build for the dependency upgrade commit created by RenovateBot:

Commit 46d66a9, build https://travis-ci.com/github/strongloop/loopback-next/jobs/323793285

> loopback-next@0.1.0 build /home/travis/build/strongloop/loopback-next
> node packages/build/bin/compile-package -b

examples/multi-tenancy/src/datasources/db.datasource.ts:40:3 - error TS2416: Property 'stop' in type 'DbDataSource' is not assignable to the same property in base type 'DataSource'.
  Type '() => ValueOrPromise<void>' is not assignable to type '() => Promise<void>'.
    Type 'ValueOrPromise<void>' is not assignable to type 'Promise<void>'.
      Type 'void' is not assignable to type 'Promise<void>'.

40   stop(): ValueOrPromise<void> {
     ~~~~


(...)

[bajtos]

I wish we scaffolded the start/stop methods with no return type, that way the compiler would infer that start returns void and stop returns Promise<void> and we wouldn't have this problem :(

[raymondfeng]

I see. Then we may need either mark this as a breaking change or continue to generate the start/stop.

[bajtos]

Cross-posting loopbackio/loopback-datasource-juggler#1835 (comment)

Ouch, looks like strongloop/loopback-datasource-juggler#1835 was not as backwards compatible as I thought 🙈 While I could change juggler's typings to describe the return value of stop method as PromiseOrValue<void>, I feel such description would be incorrect and would make the stop method more difficult to use outside of LB4 life-cycle observer use-cases.

I was thinking about this a bit more and realized that we have to fix the typings because I don't see any other way how to avoid breaking existing LB4 applications.

I opened a new PR in juggler, I would like to get it approved, merged and published today. See
loopbackio/loopback-datasource-juggler#1838

---

As for the changes proposed in 572420d, I opened a new pull request where we can discuss them separately from juggler update. Please continue the discussion in #5279

[bajtos]

(Waiting for RenovateBot to notice loopback-datasource-juggler@4.21.1 and update this pull request accordingly.)

[renovate]

PR has been edited

👷 This PR has received other commits, so Renovate will stop updating it to avoid conflicts or other problems. If you wish to abandon your changes and have Renovate start over you may click the "rebase" checkbox in the PR body/description.