mapStateToProps not always called after upgrading to 5.0.1

[tleunen]

I have a boolean value inside a reducer and the mapStateToProps is not always called when the value changes.

Here's the log from 4.4.6:

[mapStateToProps] showResults false
[reducer] previous value: false ; new value: true
[mapStateToProps] showResults true
[reducer] previous value: true ; new value: false
[mapStateToProps] showResults false

But here's the one from 5.0.1:

[mapStateToProps] showResults false
[reducer] previous value: false ; new value: true
[mapStateToProps] showResults true
[reducer] previous value: true ; new value: false
[reducer] previous value: false ; new value: false

[tleunen]

I wonder if this is related to an "app" within another app and maybe the relations between the stores are wrong since the upgrade?

[markerikson]

Can you post a sample project that demonstrates this issue? Your second comment makes it sound like your setup is more complicated than "just" a store and some components.

[tleunen]

I can try to create a new project.

But basically it's something like this:

<Provider store={store}>
  <MainApp />
</Provider>

With MainApp being:

<div>
  <div>Something</div>
  <OtherApp />
</div>

OtherApp:

<Provider store={otherStore}>
  <MiniApp />
</Provider>

[markerikson]

Ah... hold on. So you're using two different <Provider> instances, with the second nested inside the first? Are you updating the first store, but expecting a component inside the second <Provider> to respond to that update? Because if so, I really don't think that's a supported or expected scenario.

[jimbolla]

The inner Provider is shadowing the store context property, but not storeSubscription, so the connected components inside the inner Provider are incorrectly subscribing to store changes from the outer Provider's store. Easy enough to fix by changing Provider to also shadow storeSubscription, but it does beg the question "How much support does react-redux offer for multiple stores?"

[tleunen]

Are you updating the first store, but expecting a component inside the second to respond to that update?

Nop. Everything inside the "mini app" is self contained. So something inside send an action and update its own reducer. I only expect the mini app to be updated. The "parent app" has nothing to do with that.

I'm making another small project to reflect the issue. Stay tuned.

@jimbolla Maybe it's not the usual use case, but I'm having the issue because my "mini app" can live as a standalone application, but also embedded inside another app.

[tleunen]

See this project: https://github.com/tleunen/react-redux-issue582

[markerikson]

@jimbolla : I'd say that if we can fix it without much hassle, then we might as well go ahead and do so. Sounds like it's "just" a matter of adding a couple more entries to context, right?

[jimbolla]

Yep. Just submitted PR #584 to fix this use case.