chips: ng-change with read-only array-model causes problems

[fsmeier]

Bug, enhancement request, or proposal:

ng-change introduced new assignment to model-value instead of just adding/removing the elements of the array. Therefore model-values which just have a getter and no setter are not working anymore.

In some cases it is just wanted to have a property with no setter to not touch the reference to the array but let the values be changed.

CodePen and steps to reproduce the issue:

CodePen Demo 1.1.8 where it still works.
CodePen Demo 1.1.9 where it broke.

Detailed Reproduction Steps:

See codepen + look at The codeline which broke the working code.

What is the expected behavior?

Code does still work after updating to 1.1.9.

What is the current behavior?

Completely dies, latets after removing a chip.

What is the use-case or motivation for changing an existing behavior?

Make it work again without changing the application logic because of a material update

Which versions of AngularJS, Material, OS, and browsers are affected?

• AngularJS Material: 1.1.9

Is there anything else we should know? Stack Traces, Screenshots, etc.

Introduced with #11237

[Splaktar]

Completely dies, latets after removing a chip.

I'm not seeing this. I'm seeing the chip added, but the text being left in the input.
I.e.

This is obviously not desirable though.

I'm a little hazy on all of the fine details of using objects with get and set in ng-model. Can you please point me to some documentation where it says that providing the get and not the set in such a configuration is acceptable/advised?

[Splaktar]

@Free-Easy heads up that this appears to be triggered by your changes from #11166.

[fsmeier]

@Splaktar when you remove the chip and try to add another one: nothing happens for me anymore.

A quick google research did not find some article if it is good or bad.
We do this in some cases to not loose the reference to the array itself -> having some kind of caching.
Nevertheless it is a breaking change of how chips deal with the model: with this change it is the first time they change the model-object itself instead of just manipulating the items.

[Splaktar]

This seems to be related to #11304 which I am working on atm. My guess is that fixing that issue will resolve this as well.