How to do a conditional return in withObservables with a non-reactive value?

[Albert-Gao]

So, I have a user model, and have an assignedTasks() query on it, now I want to render a component with the count.

Here is how I do it. Since I need to handle the case which the currentUser is null. I was doing the step A with fetchAndObserve(), but it throws error when record not found and seems uncatchable, so I switched to a normal Q.where(), it indeed took me to the step B, now I have another problem, since the currentUser could be not there, I need to return a fallback count, otherwise, invoking currentUser[0].assignedTasks() would cause a problem like can not invoke assignedTasks on undefined.

How to solve this problem? Or I would say what is the watermelon way of solving it? Thanks :)

const enhance = compose<any, any>(
  // step A
  withObservables([], ({ database }: { database: Database }) => ({
    currentUser: database.collections
      .get(Tables.Users)
      .query(Q.where("id", CurrentUser.userId()))
      .observe(),
  })),
  
  // step B
  withObservables(
    ["currentUser"],
    ({ currentUser }: { currentUser: User[] }) => ({
      assignedToMeCount: isEmpty(currentUser)
        ? 0
        : currentUser[0].assignedTasks().observeCount(),
    })
  )
);

[radex]

Simply return foo ? Rx.of(0) : query.observeCount()

https://rxjs-dev.firebaseapp.com/api/index/function/of

[Albert-Gao]

Thanks so much, works beautifully now :)

[Albert-Gao]

is there a way to make this query return a type like User | null instead of the User[]?

database.collections
      .get(Tables.Users)
      .query(Q.where("id", CurrentUser.userId()))
      .observe()

not a rxjs guy, thus asking :) thanks in advance

[radex]

You can unwrap the array inside the component, you don't need to do it via RxJS.

But you can if you want to. Here's a snippet from @Nozbe you could adapt to your needs