[Bug] Ember octane computed properties regression

[lifeart]

Minimal reproduction: https://ember-twiddle.com/ed259f439203096ac88c0e0aaa3383f1?openFiles=twiddle%5C.json%2C

Working in 3.12
Not working in 3.13 (from beta) till 3.23

Tl dr:
nested computed properties, related to arrays not triggered

This issue does not related to ember-data, tested on (3.12 - 3.23), and only ember-source cause regression

---

One more behavour (likely not related to this bug, but may be related to computed properties)
during an large MDD app migration to Octane, I've faced to issue, related to relation tracking, using computed properties - https://ember-twiddle.com/ed17ef8abcdfca94599b2e5aa385485d?openFiles=templates.application%5C.hbs%2C
(middlename value appear in input, but not appear in template after new model was added)

Without e-data it seems working as expected https://ember-twiddle.com/222a3f1e1bb9f244b35a725fc03621f7?openFiles=templates.application%5C.hbs%2C

[lifeart]

simplier regression case: https://ember-twiddle.com/d83a6cf6d6d7ce0a71d9686f4ff202ad?openFiles=templates.application%5C.hbs%2C

[lolmaus]

simplier regression case

Your CP allAdditives depends on metaAttributes.@each.countAdditives but is not using it. Instead it uses metaAttributes.@each.additives.[] which Ember has been known not to support.

When I rewrite your CP to use metaAttributes.@each.countAdditives it does recompute correctly.

Can you update your reproduction such that CPs use exactly the properties they depend on and don't access two arrays deep in one CP?

[lifeart]

@lolmaus countAdditives is alias to additives.length, and it should invalidate computed property because I'm pushing values to additives array, and this is behavour is working fine just before octane

[lolmaus]

AFAIK:

1. Ember documentation says somewhere that a CP can not depend on a property two levels deep into arrays.
2. Ember documetnation says somewhere that if a CP uses a property in its code then this property should be listed in that CP's dependencies. It's kinda wront to depend on A but use B.

But I was able to reproduce this bug while adhering to these two points!

Repro (set to 3.13.1, works with 3.12.1):
https://ember-twiddle.com/f1c5b4ecb5c4eed81c729559cdfe63cc?numColumns=2&openFiles=controllers.application\.js%2Ctemplates.application\.hbs

  // still need `countAdditives` to trigger recomputation
  allAdditiveArrays: computed('metaAttributes.@each.{countAdditives,additives}', function () {
    return this.metaAttributes.map((meta) => meta.additives);
  }),

  allAdditives: computed('allAdditiveArrays.[]', function(){
    return [].concat.apply([], this.allAdditiveArrays); // flatten array of arrays
  }),

[lolmaus]

Oh, I just forgot how to do it properly. The flattening CP should depend on arrayOfArrays.@each.[]. 😎

This works in 3.13.1:

  allAdditiveArrays: computed('metaAttributes.@each.additives', function () {
    return this.metaAttributes.map((meta) => meta.additives);
  }),
  
  allAdditives: computed('allAdditiveArrays.@each.[]', function(){
    return [].concat.apply([], this.allAdditiveArrays);
  }),

https://ember-twiddle.com/eff8e81ab024dc8bcf5cc39d833c7d66?numColumns=2&openFiles=controllers.application%5C.js%2Ctemplates.application%5C.hbs

[lifeart]

closing it, because fix is merged to 3.24