ngOnChanges produces changes for every input, even when the objects are unchanged.

Problem: ngOnChanges seems to always provide all inputs in the SimpleChanges object, even though some inputs are unchanged. Correct behavior would be that only the changed inputs are provided, similar to the Angular implementation.

Repro steps:

• Open stackblitz
• Click on val1 button, which changes the someValue property on HelloComponent.
• Notice in the console that the following SimpleChanges object is generated. The issue is that name should not come up as a change, since it has not changed.

{
  "name": {
    "previousValue": "World",
    "currentValue": "World",
    "firstChange": false
  },
  "someValue": {
    "previousValue": "myvalue",
    "currentValue": "val1",
    "firstChange": false
  }
}

My own debugging shows that all bound input properties are always marked as changed. I can work around it for now by checking for equality myself in the ngOnChanges method of my component, but a fix would of course be preferable.

[gund]

🎉 This issue has been resolved in version 7.0.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[gund]

During deeper investigation is turns out that Angular’s differ works fine and library was using incorrect API to collect changes from it.

Currently new records are collected from forEachAddedItem() method and changed records from forEachItem() method which always returns all items despite any changes (which is logical). See: https://github.com/gund/ng-dynamic-component/blob/a4dd16067907df6b975b757369ae482b2bbc32c3/projects/ng-dynamic-component/src/lib/io/io.service.ts#L241-L245

But there is another method forEachChangedItem() that returns only changed records and behaves correctly. See demo https://stackblitz.com/edit/angular-keyvalue-differ?file=src%2Fapp%2Fapp.component.ts

So I’m preparing a fix now and will release soon. Thanks again for the reported bug with reproduction demo!