Provide consistent hook APIs for methods mixed into model classes from connectors

[raymondfeng]

When a LoopBack model is attached a data source, the underlying connector will mix in a list of methods on the model class. If the connector is backed by one of the databases, the methods are the CRUD operations. At the moment, the juggler only has hard-coded before/after hooks that have serious issues:

1. The before/after hook only allows one handler
2. The triggering of hooks are hard-coded in the lib/dao.js
3. Not all paths are covered

See open issues or pull requests:

• fix beforeDestroy and afterDestroy hooks not trigered if called with destroyById #363
• add hooks module and support pre && post #359
• Validators are not triggered on updateOrCreate #262
• beforeDestroy and afterDestroy hooks not trigered if called with destroyById #202
• DataAccessObject.upsert/updateOrCreate - no hooks triggered #159
• Some model hooks ignore errors passed to the callback strongloop/loopback#614
• afterDestroy hook not called on REST remoting (deleteById) #142

Tasks:

• Finish and land Operation hooks for persistent models (intent-based hooks) #403
• Land before delete hook Implement intent hook before delete #412
• Update docs draft for before delete hook
• Write documentation for the new hook API.
• Rename query to access (Rename hook "query" to "access" #418) and update docs
• Clean up change-detection events, let them use the new API - see Refactor change tracking to use the new hook infrastructure strongloop/loopback#1048
• Add test/persistence-hooks.suite.js to connector tests: Not strictly needed, since all hooks are implemented inside juggler.

Out of scope (follow-up):

• Per-method hooks Per-method hooks #397
• Advance hook use-cases Advanced hook use-cases #417

[STRML]

Re: the usage of hooks-js, I used to contribute to that module back in the day (see version 0.3.0) - would be happy to help you guys get it into Loopback if you have questions about it. It's a good module with a consistent API.

[faridnsh]

What's the status of this? anyone working on it? Since I need to have multiple handlers in my app, I can work on this. I assume you guys prefer to use loopback-phase for this.

[bajtos]

@alFReD-NSH I am starting to work on this today.

I assume you guys prefer to use loopback-phase for this.

Not necessarily.

[STRML]

What would you like to use, then? It should be a pretty simple impl with
hooks-js.
On 1/15/15 9:05 AM, Miroslav Bajtoš wrote:

@alFReD-NSH https://github.com/alFReD-NSH I am starting to work on
this today.

I assume you guys prefer to use loopback-phase for this.

Not necessarily.

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#367 (comment).

[bajtos]

@STRML What would you like to use, then? It should be a pretty simple impl with
hooks-js.

First I need to get more familiar with the way how the current hooks work, including various quirky edge-cases. Then I'd like to come up with a proposal how the hooks should work instead and discuss it here.

Whether we will end up using hooks-js or a different module is an implementation detail. I'll worry about that after we agree on what is the desired behaviour.