Onyx collection values sometimes appear as null to subscribers. #310

Coming from Expensify/App#25481 (comment)

Problem

Generally, to delete stuff from Onyx you set it to null. However:

• Given a subscriber to a collection key with waitForCollectionCallback: true
• When a collection member key is set to null
• Then the subscriber should get the new complete collection with any null values removed

However, the subscriber is getting the new collection with a null value for the item that was meant to be deleted.

Solution

TBD. According to a contributor:

it is due to notify the subscribers with the changed values before updating the storage.

react-native-onyx/lib/Onyx.js

Lines 508 to 515 in 79bfb5e

	// Subscriber is a regular call to connect() and provided a callback
	if (_.isFunction(subscriber.callback)) {
	if (isCollectionKey(subscriber.key) && subscriber.waitForCollectionCallback) {
	const cachedCollection = getCachedCollection(subscriber.key);
	cachedCollection[key] = data;
	subscriber.callback(cachedCollection);
	continue;
	}