[mobx ^2.5.0] mobx.observable property inside of mobx.extendObservable doesn't return an ObservableValue instance

[pnpetrov]

Hello,

I have a store with a state object inside of it. I want to extend the state with some observable primitive values.

this.state = {};
mobx.extendObservable(this.state, {
  title: mobx.observable('hello')
});

With mobx v2.4.4 this.state.title is of type ObservableValue so I can attach some observers. But with mobx v2.5.0 this.state.title is not an observable value anymore.

mobx.observable(<scalar_value>) still returns an ObservableValue instance but it behaves differently if I use it inside of mobx.extendObservable.

Here is an example with mobx v.2.4.4: https://jsfiddle.net/ppetrov/emrLLhk7/

EDIT: mobx v2.5.0 example: https://jsfiddle.net/ppetrov/4wocz8y4/

[andykog]

@nikolovp, thanks for reporting. As a quick workaround you can use:

mobx.extendObservable(this.state, {
  title: mobx.asReference(mobx.observable('hello'))
});

Or, obviously, that could be rewritten like this: https://jsfiddle.net/Sl1v3r/rg0oqkod/

@mweststrate, converting ObservableValue to a plain value is not the desired behaviour, right?

[mweststrate]

Ah this is a bug indeed I think, introduced here (the idea was that this is consistent with computed, but that is actually another use case, and getters are now the idiomatic way). I'll revert the behavior.

[mweststrate]

Fix will be part of 2.5.2