FormArray triggers onFormUpdate too early

[4typen]

Refering to https://github.com/cloudnc/ngx-sub-form#dealing-with-arrays i propably found an issue with the initial building of the FormArray.

The method onFormUpdate(...) triggers when the form gets prefilled by the data of getInitialModel(). So the FormArray crewMembers seems to be updated at this time. Instead you have to use this.formGroup.valueChanges.subscribe(...) after super.ngOnInit() to correctly watch for changes.

[maxime1992]

I've been discussing that with @zakhenry for a while, but I suspect it might be a good idea to deprecate the onFormUpdate method. And that makes another point for it 😅

@4typen are you using it a lot within your app?
Is anyone reading this issue using onFormUpdate heavily and would be against deprecating it?

[4typen]

@maxime1992 We use it a few times, but we can change it easily i think. So deprecating onFormUpdate is no problem.

[maxime1992]

https://github.com/cloudnc/ngx-sub-form/releases/tag/v4.0.1 just got release and embed the deprecation of the method :)

#129 has been merged into the next branch so it'll be fully removed on the next major upgrade 👍

[CyberBotX]

I hadn't noticed this being here until the 4.0.1 update happened. I've been using onFormUpdate in my own code. What I'm not seeing is what should be used in place of it. My cases for using it have been when I want to have other actions happen as a result of a form value changing.

[maxime1992]

@CyberBotX instead of it you can simply subscribe to the formGroup.valueChanges or formControls.someValue.valueChanges.

BUT, I don't think that this hook was a good idea in the first place. If you end up doing things based on some form values, in a lot of cases it'll probably be something you should do in the parent of that component. Forms should only deal with the form value and not manage side effects IMO. Plus, as the hook is not dealing with observables you'd probably have to use subscribe into it which is a bad idea.

But I may be missing some use cases. Would you mind sharing the code of your components using onFormUpdate? Maybe I'll help you spot something that could be done in a better way or I'll realize I missed something and we shouldn't deprecate it :)

[CyberBotX]

A specific example I have is here: https://www.cyberbotx.com/angular/MutePrincess/src/app/Components/data-input.component.ts (if you want to browse up in the source tree, feel free to do so) with the fully running app at https://www.cyberbotx.com/MutePrincess.php

In that example, the data input component has a collection of radio inputs, usually when one is selected, nothing special happens in the data input component and the information is passed as-is to the root component. But if the "Other" option is picked, I show a color picker, which is handled differently from all the other colors. Using onFormUpdate was the only thing I could think of at the time. I don't know if subscribing to the valueChanges of the control would be better in this case or not. If you need other examples, I can provide some more.

[maxime1992]

onFormUpdate has been deprecated as explained here and will be removed at some point.

I'd definitely encourage you to listen to valueChanges instead 👍

Closing as the method in question is deprecated

PS:

(if you want to browse up in the source tree, feel free to do so) with the fully running app at https://www.cyberbotx.com/MutePrincess.php

Funny app btw 🙃!