[mobx6] @action.bound decorator not binding

[anri-asaturov]

Intended outcome:

Trying to use @action.bound in a class with makeObservable(this) and reference @observable property of the same class. The solution from #2468 does not work.

class C {
  @observable x!: number; // if assigned here - works

  @action.bound // but not really
  incX() {
    this.x++;
  }

  constructor() {
    // this.x = 0 // if assigned here - works
    makeObservable(this);
    this.x = 0; // if assigned here - breaks
  }
}

Actual outcome:

Action is not getting actually bound.
Surprisingly, initializing property makes action bound properly.

How to reproduce the issue:

https://codesandbox.io/s/distracted-glade-y30yg?file=/src/index.ts

[mweststrate]

Please check existing issues or the mobx migration guide.

…

On Sat, 17 Oct 2020, 22:08 Anri Asaturov, ***@***.***> wrote: *Intended outcome:* Trying to use @action.bound in a class with makeObservable(this) and reference @observable property of the same class. The solution from #2468 <#2468> does not work. class C { @observable x!: number; // if assigned here - works @action.bound // but not really incX() { this.x++; } constructor() { // this.x = 0 // if assigned here - works makeObservable(this); this.x = 0; // if assigned here - breaks }} *Actual outcome:* action does not getting actually bound. Surprisingly, initializing property makes action bound properly. *How to reproduce the issue:* https://codesandbox.io/s/distracted-glade-y30yg?file=/src/index.ts — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#2522>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAN4NBE5OF7RGBYVTHBP3LDSLIBVNANCNFSM4SUTNKDQ> .

[anri-asaturov]

@mweststrate I did, if you're referring to tsconfig.json: "useDefineForClassFields": true - it is set there in the sandbox.

[anri-asaturov]

I raised this issue because you asked to do it here #2467 and it's still reproducing in 6.0.1

[mweststrate]

Ah yes, sorry, was reading to quickly, apologies.

This is probably an earlier reported babel bug, it has been fixed already, but it might not yet be available in Parcel / Code Sandbox already. See #2486, babel/babel#12146. Best check first if Babel 7.12 or higher is used behind the scenes.

[anri-asaturov]

@mweststrate I was just trying to figure out why can't I reproduce it locally, so you're probably right, thank you.

[mweststrate]

Added it to the docs, since more people will probably stumble on it as well.