Mobx/Mobx-state-tree doesnt work in module federation of Webpack.

[AshwinAsp]

Bug report

• [x] I've checked documentation and searched for existing issues and discussions
• [x] I've made sure my project is based on the latest MST version
• [x] Fork this code sandbox or another minimal reproduction.

Sandbox link or minimal reproduction code

Minimal Reproduction is complex as it involves creating multiple deployed static environments.

Describe the expected behavior

MST should work in any environment. i.e. Microfronts / Module Federated environment

Describe the observed behavior

Its always throwing the error Error: [MobX] minified error nr: 27 __ob__,AnonymousModel. Find the full error at: https://github.com/mobxjs/mobx/blob/main/packages/mobx/src/errors.ts at r (remoteEntry.js:2:117398) at Jr (remoteEntry.js:2:175698) at Xr (remoteEntry.js:2:175833) at t.value (remoteEntry.js:2:88909) at t.value (remoteEntry.js:2:29294) at Array.value (remoteEntry.js:2:88166) at tr (remoteEntry.js:2:154042) at t.defineProperty_ (remoteEntry.js:2:170740) at Object.defineProperty (remoteEntry.js:2:153623) at Function.defineProperty (<anonymous>)

More description and screenshots:

The MST integration with a simple example like the one attached below is working smoothly in a local dev environment but failing on a deployed environment. Since there is no existing bug reports or proper error tracking in MST it is very difficult to debug this error. What could be the possible cause that it throws no observable property '${property.toString()}' found on the observable object '${name}' only in a deployed environment.

Code: Store.ts

import { types } from 'mobx-state-tree';

const Todo = types.model({
  title: '',
  done: false,
}).actions((self) => ({
  toggle() {
    self.done = !self.done;
  }
}));

const User = types.model({
  id: '',
  name: '',
  isLoggedIn: false,
});

const RootStore = types
  .model({
    users: types.array(User),
    todos: types.optional(types.array(Todo), []),
  })
  .actions((self) => ({
    addTodo(title: string, done: boolean) {
      self.todos.push(Todo.create({ title, done }));
    },
    addUser(id: string, name: string, isLoggedIn: boolean) {
      self.users.push(User.create({ id, name, isLoggedIn }));
    },
  }));

const store = RootStore.create({
  users: [], // users is not required really since arrays and maps are optional by default since MST3
});

export default store;

Component.tsx

import store from './Store';

const Screen = () => {
  console.log(store.users.at(0));

  useEffect(() => {
    store.addTodo('Patient', false);
    store.addUser('ZB123', 'John', true);
  }, []);
}

Local Environment

Deployed environment

[coolsoftwaretyler]

Hey @AshwinAsp, thanks for the bug report!

I've used MST successfully in Repack, which is a federated module system. But I haven't tried it with the tech you mentioned here. I will have to look into it more.

Also, reading the error closely, it seems possible this is a MobX issue, not a MobX-State-Tree issue. The first sentence of the error that says "find the error at..." Seems to be pointing to the MobX codebase and not us.

Have you checked with MobX or filed an issue there?

[AshwinAsp]

@coolsoftwaretyler When I did unprotect(store) it starts loading but bunch of irrelevant errors are coming now. Like Uncaught Error: [mobx-state-tree] users property is declared twice eventhough there's only one declaration. And unprotect and the error thats coming now is coming from mobx-state-tree. Now again the weirder part is in development environment there is no problems. But this is happening only after is deployment and in the integrated mode of MFE.

[coolsoftwaretyler]

Interesting. This is a strange one! I know you said a reproduction would be tough but I think we'll need to repro this to really get the bottom of things.

Can you describe the environment and maybe link to the technology you're using so we can try to put something together?

[AshwinAsp]

Ill try to add a reproduction repo soon

[AshwinAsp]

We have a legacy app using Vue2 with webpack which is hosting the MFE application. The MFE is a react application also using webpack to bundle this. Im not sure if the stack has any implication of the code because if its works for localhost it should work for server as well. I mean in standalone mode it does work but not in the integrated mode. Eventhough the same code is used in both the modes

[coolsoftwaretyler]

@AshwinAsp - does your local environment do the same minification step as your production deploy? I don't know a lot about MFE, and without a repro I don't have a good place to start, so please forgive me if this is an irrelevant question.

But if there's a difference between local and prod, a build step like minification seems like a good place to start with troubleshooting. Can you try turning off that step for MST or for the whole app and getting it into a production-like environment to see if that helps?

If so, that will help us narrow down or remove this as a possible culprit.

[AshwinAsp]

I wish I can add a repo for replication. But that would involve creating a new project with all the dependencies and build steps to match our current projects. But no there is no difference in the build/minification process as we test the built code locally which would have the same build steps.

On Wed, Jun 19, 2024, 8:22 PM Tyler Scott Williams @.***> wrote:

@AshwinAsp https://github.com/AshwinAsp - does your local environment do the same minification step as your production deploy? I don't know a lot about MFE, and without a repro I don't have a good place to start, so please forgive me if this is an irrelevant question.

But if there's a difference between local and prod, a build step like minification seems like a good place to start with troubleshooting. Can you try turning off that step for MST or for the whole app and getting it into a production-like environment to see if that helps?

If so, that will help us narrow down or remove this as a possible culprit.

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[coolsoftwaretyler]

I totally understand. That just means we may not be able to help you entirely.

Have you tried my suggestion of turning off minification? Any improvement there?