Is local state management really needed when using firebase?

Question

(this was originally a post on the flutter-dev reddit that was redirected here)

So I started making this flutter app using firebase as a backend and after looking at all the options for state management I finally realised that the tools provided by firebase already handle pretty much everything I would need state management for.

For example:

I could set the currently logged in user in my state to show the right login or home page and make the user uid available to widgets for their firestore API calls.

OR

I can just listen to FirebaseAuth.instance.onAuthStateChanged to show the right page and just use FirebaseAuth.instance.currentUser() from anywhere to get the logged in user uid and do my firestore calls.

What I mean is, for every thing that would require global state, I can just basically have a firebase stream listener.

Is this right ? Or am I missing something here ?

Answer 1

You're not missing anything. Since most Firebase APIs rely on data from Google's servers, many of them are designed to be used in a reactive way. Making your UI reactively respond to those asynchronous changes is (in my experience) the best way to keep your code simple.

There may be slight behavior between the different types of listeners. But the onAuthStateChanged listener immediately fires with the current state when you attach it, which makes it a good example of a listener that you can use everywhere you need to respond to auth state (instead of also storing that state somewhere in your app).

Answer 2

In that scenario I would say yes, you can read the onAuthStateChanged stream and react to changes. But there are also scenarios where I need a stream for interacting between widgets without a parent/child relationship. For example, in one of my apps I have a company selector, and the rest of the app reflects to the selected company. I created a stream, so that the company selector doesn't need to be a parent of the other widgets, and especially so that I don't need to pass the company parameter to all the widget tree.

I also have one scenario where I need to load extra information about the user that isn't available on the FirebaseUser object. So when the user is logged on I load their information from a "users" collection and then I add that to a custom stream.

So to conclude I would say yes, you should use the default Firebase streams when possible, but that doesn't mean you can or should use that solution for everything.