Messing around with Room for the first time, and w...

# coroutines

[Brandon Trautmann]

Messing around with Room for the first time, and wondering what you all think about this usage:

viewModelScope.launch {
customerRepo.customer(customerUid) // Returns a `Flow<Customer>`
  .combine(controllerRepo.controllersForCustomer(customerUid)) { customer, controllers ->
    CustomerWithControllers(customer, controllers)
  }
  .collect { customerWithControllers ->
    internalState.value = State.Loaded(customerWithControllers)
  }
}

This works just fine, but when I go to delete a customer, the deletion cascades to the controllers and what you end up with is a new CustomerWithControllers with empty controllers because the customer Flow last emission was the customer that was just deleted. I solved this by holding onto the Job returned by launch, and when I go delete a customer, I basically cancel that Job, delete the customer, and then execute a function that checks for the existence of any customer and if one doesn't exist, brings the user to a FTUX screen. Is this a decent way of handling this? It'd be nice if Room had some way to emit an Empty token or something to indicate the table is empty 🤔

[Brandon Trautmann]

Posted this here since it's sorta a "best practice coroutine usage" question versus a Room one (since I'm fairly certain there's no Empty token in Room)... Another way of asking would be "is combine a good idea here?"

[Brandon Trautmann]

In a different Slack group it was recommended my Flow return a nullable type, so that may be the direction I have to go!

[rkeazor]

Hmm can't you just do filter a , for only valid CustomerWithControllers ? Or perhaps a custom channelFlow, that only calls

controllerRepo.controllersForCustomer(customerUid))? upon a valid return of customerRepo.customer(customerUid)

[rkeazor]

@Brandon Trautmann (aka Mr. fakesOverMocks 😅