PaperForm throwing backtracking assertion 3.16 +

[betocantu93]

Hello, trying to upgrade to 3.16.2 but got this error, starting from 3.16.0 AFAIK.

Related PR: emberjs/ember.js#18554

<PaperForm as |form|>
  {{#if form.isInvalid}}
    This form is invalid
  {{/if}}
  <form.input @onChange={{action (mut this.value)}} @value={{this.value}} @required={{true}}/>
</PaperForm>

Throws

[betocantu93]

A monkey-patch or quick fix is to rewrite the isInvalid and isTouched computeds to normal props that are setted by observers using scheduleOnce.

import PaperForm from "ember-paper/components/paper-form";
import { observes } from "@ember-decorators/object";
import { scheduleOnce } from "@ember/runloop";

export default class PaperFormComponent extends PaperForm {
  isInvalid = null;
  isTouched = null;

  setProp(key) {
    this.set(key, this.get("childComponents").isAny(key));
  }

  @observes("childComponents.@each.isInvalid")
  isInvalidObserver() {
    scheduleOnce("afterRender", this, this.setProp.bind(this, "isInvalid"));
  }

 @observes("childComponents.@each.isTouched")
  isTouchedObserver() {
    scheduleOnce("afterRender", this, this.setProp.bind(this, "isTouched"));
  }
}

[miguelcobain]

This is indeed a problem.

I'd just like to point out another workaround that is just using isInvalid afterwards, and possible using flex's order or other styling to position the invalid dependent content where you need it.

<PaperForm as |form|>
  <form.input @onChange={{action (mut this.value)}} @value={{this.value}} @required={{true}}/>
  {{#if form.isInvalid}}
    This form is invalid
  {{/if}}
</PaperForm>

Not sure how to fix this the correct way since this is, by definition, something that depends on things rendered "afterwards".

[betocantu93]

Yes, I'm not sure either how to refactor this... maybe we could ask @pzuraq for advice

[mtrunt]

I found the same assertion error when trying to implement a similar logic to ParentMixin and ChildMixin and solved it by changing the init on the ChildMixin to didInsertElement; however this was only a 1 level deep relation (parent won't be the child of another parent).

[betocantu93]

I think the init func in childMixin could have afterRender...

import { scheduleOnce } from "@ember/runloop";
export default Mixin.create({
init() {
    this._super(...arguments);
    if (this.get('parentComponent')) {
      let fn = () => {this.get('parentComponent').register(this)}
      scheduleOnce('afterRender', this, fn);
    }
  },
});

[Bartheleway]

Any updates on this ? For what it's worth, I think the correct way to handle all this parent/child nightmare is through events.
I will try to solve this, no promises ;)