State transition directly to disconnected

[rocketraman]

Experimenting on Android. When I receive an advertisement, I am launching a collect on peripheral.state, and I see immediately a state of Disconnected(status=null).

The peripheral has not previously been in a Connected state, and in fact, not even the Disconnecting state is seen prior to Disconnected, which as far as I can tell from the state diagram in the README, should not be possible.

[twyatt]

Good point, the diagram doesn't properly represent that Peripheral's state is a StateFlow with a default value of Disconnected.

The diagram should be updated and/or the default value of the state should be changed (perhaps to null — to more accurately represent the unknown state).

...not quite sure if having null as default adds any value. Is there a use-case you're hitting where knowing that the state is unknown (rather than Disconnected) would be helpful?

[rocketraman]

...not quite sure if having null as default adds any value. Is there a use-case you're hitting where knowing that the state is unknown (rather than Disconnected) would be helpful?

After I receive an advertisement for a compatible device, I have an application state called "visible", which means that I've seen the advertisement, but have not yet connected to the device. After I connect to the device, it becomes "connected". However, I think my app logic with the current setup is ok -- I attempt to differentiate "Disconnected but Visible" vs "Really Disconnected" based on the disconnected status. So maybe this is just a documentation issue.

Especially if #521 is resolved, then there would be no ambiguity between "Really Disconnected" and "Disconnected but Visible".

[jeddchoi]

I'm also having this issue. It changes directly Connected to Disconnected(Timeout).
Because state is Disconnected before connection, I have to run some operation on Disconnecting, but can't.

Is it okay to use Disconnected.status != null to distinguish from initial(before connection) disconnected state?
-> Oh, it's not ok. On android app, it can be Disconnected(133) before connection.

[twyatt]

@jeddchoi can you describe your use-case in more detail?

Are you trying to perform an action on disconnect? If so, is there a reason you can't do something to the effect of?:

peripheral.state
        .filterIsInstance<Disconnected>()
        .onEach {
            // todo: perform desired action on disconnect
        }.launchIn(scope)

[jeddchoi]

I'm making seat reservation android app using beacon. There are user states such as Reserved, Occupied, Away, etc.
When user reserve a seat and goes close to seat which has beacon, ble connection is established and change user state to Occupied. And if user leaves away from the seat and ble connection is disconnected, user state is changed to Away.

So this use case is that I need to do some operation when ble connection is disconnected after connection.
Because peripheral.state default state is Disconnected, I can't do operation on Disconnected.

peripheral.state
.filterIsInstance()
.onEach {
// todo: perform desired action on disconnect
}.launchIn(scope)

I think your above suggesstion would not distinguish between first Disconnected before any connection and Disconnected after connection.
I would be grateful if you change default state to some kind of state like Unknown as you said.

[jeddchoi]

After more investigation, I found that its state goes like Disconnected(null) -> Connecting.Bluetooth -> Disconnected(133) -> Connecting.Bluetooth -> Disconnected(133) -> ... -> Connecting.Bluetooth -> Connecting.Services -> Connecting.Observes -> Connected.

I think I need some flag or Disconnected.Status to show whether it was connected successfully or not.

I need to separate as below.

• Initial Disconnected before any connection attempt
• Disconnected with connection failure(ex. 133)

---

• Disconnected after successful connection