Child_added supported in sync? -> Adding to Documentation

[ReactNativeBlog]

First of all: Great Work!

I'm currently wondering which data is transferred on a sync in case a child was added/remove/... in the realtime database?
Is the whole data/ref transferred or only the delta?

Many thanks for clarification.

[n6g7]

Thanks!

Yes, the database.sync method currently uses the value event so it will send the whole data in the ref.

If you want to only receive new or deleted children you can choose the event you want to use (child_added, child_removed , child_changed or child_moved , see the Reference.on docs for more details), in the database.channel method:

function * syncAddedChildren () {
  const channel = yield call(rsf.database.channel, 'items', 'child_added') // 👈 add a third argument here 😉

  while (true) {
    const data = yield take(channel)
    yield put(actionCreator(data))
  } catch (err) {
    yield put(failureActionCreator(err))
  } finally {
    if (yield cancelled()) channel.close()
  }
}

It never occurred to me that there was a strong use case for this but if that's the case for you we can definitely add an API to make this a lot simpler. :)
I'm thinking of something like:

function * syncAddedChildren () {
  yield fork(
    rsf.database.sync,
    'items', 
    { successActionCreator: ..., failureActionCreator: ... },
    'child_added' // 👈 we could add a third argument here 🙂
  )
}

Please let me know if that would be interesting to you! :)

[ReactNativeBlog]

Great !!!
Possible scenarios for such an API are

• chat system
• events with bad wifi and >10.000 app users

Thanks for the clearance.
And yes, this is interesting ;-D

Kind Regards

BTW: I'm using this in react native - firebase sync & saga is super easy due to your library!

[n6g7]

Thanks for the feedback, this is much appreciated. :D

Possible scenarios for such an API are

• chat system
• events with bad wifi and >10.000 app users

That sounds reasonable, I'll keep this issue open and notify you when this is ready. :)

[n6g7]

@ReactNativeBlog I've just released v0.8.0 with this change!
Run yarn upgrade redux-saga-firebase@latest (there's no breaking changes) and you should be able to use the new database.sync event argument in your code. 🎉

Let me know how it works for you! :D