injected objects are reactive (despite documentation saying the opposite)

[akarelas]

Version

2.3.3

Reproduction link

https://jsfiddle.net/50wL7mdz/41000/

Steps to reproduce

Provide (from parent component) an object with a pre-existing key. Inject that object into child component. Either console.log the object to see that it is reactive, or modify the value of the pre-existing key to see that the value also changes on screen automatically.

What is expected?

According to vue's documentation, injected objects are not reactive: "Note: the provide and inject bindings are NOT reactive.". The value should not change on the screen after 3 seconds, and console.log should not display the word Getter when logging the injected object.

What is actually happening?

The injected object is reactive, and so the message changes on screen after 3 seconds, and console.log'ging the object shows it is reactive (displays the word Getter)

---

I use inject to inject commonly used libraries in objects, like moment, which I can then use in the templates to display nicely formatted dates. If the entire moment library object becomes reactive, then this will probably cause an unnecessary performance hit to the browser when using the moment library.

[LinusBorg]

Hm, indeed. Thanks for reporting this!

It seems #5204 introduced this, but I don't think this was intended.

@yyx990803 I think this is a regression from the original, intended behaviour of inject - would you agree?

[Kingwl]

thanks for reporting this!
@LinusBorg actual #5229 introduced this
it seems a regression...my fault

[Darival]

I'm glad I found this, I was pulling my hair off.

Is this the same that is happening to me?

https://jsfiddle.net/50wL7mdz/41229/

look how updating childObj.msg in component also updates someObj.msg in parent T.T

[Kingwl]

@Darival in #5229

We can just use that to do the warning when a child component attempts to mutate an injection binding. This is what we are doing for props too

IMO you shouldn't mutate an injection the same as react context....

[rayrutjes]

Personally I considered this change as a feature more than a bug.

[LinusBorg]

@rayrutjes the injected properties themselves were left unreactive pretty much for the reason OP provided: So you can inject arbitrary objects, inlcuding complicated ones, in the background and have them left untouched.

If you need reactivity, just pass down an already reactive object - best of both worlds. ;)

[Kingwl]

@LinusBorg
but the injected array will not changed even it is really reactive...

[rayrutjes]

@LinusBorg I think that makes sense. Wondering how this will affect our existing code base ;)

[LinusBorg]

@Kingwl Could you make a PR to revert this behaviour?

[Kingwl]

@LinusBorg i'm going to try it tomorrow...