SetProps on object prop child changes does not trigger computed or watcher

[drewtownchi]

Version

1.0.0-beta.20

Reproduction link

https://github.com/drewtownchi/VueRouterTranspile

Steps to reproduce

Create some data to be passed down as a prop...

prop1: {
    sub1: "hello",
    sub2: "data2"
}

Create a component that accepts an object prop.
Initialize the test with propsData and verify the child key sub1 is set correctly via the computed property to "hello".
Change the sub1 data in the test to "test2" and update the props using setProps
Check that the sub1 is set correctly via computed property or data (if using a watcher, both don't work)

    expect(wrapper.vm.someData).toBe("hello");
    propsDataForNew.sub1 = "test2";
    wrapper.setProps({
      prop1: propsDataForNew
    });
    expect(wrapper.vm.someData).toBe("test2");

What is expected?

the computed property would be updated to the new data passed down via props

What is actually happening?

The computed property is giving the old data.

Expected: "test2"
Received: "hello"

---

This is working correctly in the browser. The data outputted to the screen reflects the change in sub1 when sub1 is changed in the parent.

Edit: This was working before in previous versions. So maybe I am just doing it the wrong way now? Now should I be just passing in the updated key?

    wrapper.setProps({
      prop1: {
        sub1: "test2"
      }
    });

This seems to work. Not sure if I should no longer be passing in an updated object?

[drewtownchi]

The above "working" example doesn't actually work because other properties on the object are unset by calling setProps with the partial object.

So, it seems like I should be passing in the full object to setProps still but it isn't forcing an update on computed/watchers.

It does seem the reactivity does happen if I copy the the initial object with Object.assign or the spread operator and then change the copied object.

[eddyerburgh]

Yes the problem is you're calling setProps with the same object.

When setProps reassigns the same object, the property getter returns early because the object reference hasn't changed.

I'll look into a way to fix this

[eddyerburgh]

The solution has been to throw an error if you're doing this.

Instead, you'll need to create a new object when you call setProps

[CindyConway]

The above comment says you will need to ' create a new when you call setProps'. A new what. It looks like a word is missing.

[eddyerburgh]

@CindyConway a new object