What you and the above reply are suggesting is to write a reconciler by hand. I gave a code example of this way up in reply 7, though I understand that it’s been kinda buried.
The problem, which I tried to explain at the time (but maybe not well enough?), is that this does not work in general in LiveView because there is no unmount.
As a simple example, say you have a live chat component that you want to embed into your LiveView. When the user opens it, it subscribes to the topic. LiveComponents cannot receive messages on their own but you can fix this with a router (see reply 3).
The problem is that when the surrounding LiveView decides to close the chat component, i.e. remove it from the page, it cannot unsubscribe from the resource because there is no unmount callback for it to use.
So the reconciler that all three of us have suggested here is incomplete. It is two thirds of a reconciler. It can mount and update but not unmount. This is not acceptable.
The reason you can get away with it in the simple case is luck: it just so happens that a root LiveView always replaces itself. This convenience does not generalize to a real application. Once you add more functionality to your app you will need components, and when that need comes the solution will break down.
One thing I’ve been wondering is how PhoenixSync handles this. I had a look at the code and the router is there, so you can indeed subscribe to a stream from a component. But where is the unsubscribe? I could be wrong, but I don’t see it. It kinda looks to me like the subscriptions are just held open forever when the components unmount.
LiveView needs a real solution to this problem. I will say again: if anyone actually has a solution, please post it. I do not.
