More information around QueryCacheNotifyEvent

[romellem]

queryCache.subscribe(callback) calls the callback() with an event: QueryCacheNotifyEvent argument. Here are the possible types that event might be:

query/packages/query-core/src/queryCache.ts

Lines 22 to 59 in 3c9df20

	interface NotifyEventQueryAdded {
	type: 'added'
	query: Query<any, any, any, any>
	}
	interface NotifyEventQueryRemoved {
	type: 'removed'
	query: Query<any, any, any, any>
	}
	interface NotifyEventQueryUpdated {
	type: 'updated'
	query: Query<any, any, any, any>
	action: Action<any, any>
	}
	interface NotifyEventQueryObserverAdded {
	type: 'observerAdded'
	query: Query<any, any, any, any>
	observer: QueryObserver<any, any, any, any, any>
	}
	interface NotifyEventQueryObserverRemoved {
	type: 'observerRemoved'
	query: Query<any, any, any, any>
	observer: QueryObserver<any, any, any, any, any>
	}
	interface NotifyEventQueryObserverResultsUpdated {
	type: 'observerResultsUpdated'
	query: Query<any, any, any, any>
	}
	interface NotifyEventQueryObserverOptionsUpdated {
	type: 'observerOptionsUpdated'
	query: Query<any, any, any, any>
	observer: QueryObserver<any, any, any, any, any>
	}

I'm curious about the differences between these types, and in particular what we expect to change when the events are fired? Is it expected that updated will have its query.state.data changed? Or will that only happen when observerResultsUpdated is fired?

Basically just looking for more documentation around these event types, and what kinds of differences are expected on an underlying query object when one of these types are fired?

• added
• removed
• updated
• observerAdded
• observerRemoved
• observerResultsUpdated
• observerOptionsUpdated

[TkDodo]

added and removed events should be self explanatory, as well as observerAdded and observerRemoved.

updated means a query was updated. Yes, in query you can expect the new state, something has changed in here.

observerOptionsUpdated - the options of an observer have been updated. You can expect this to be fired when there is a useQuery and the options that are passed to it change.

observerResultsUpdated - when the result of an observer has been updated 😅. Not sure what much else to say here, an observer could theoretically have the same result even though the query changed, because it is subscribed to a sub-set of the query via select.