[Question] How to clear the cache of a loader from a service?

[GauthierPLM]

I'd like to purge the cache of my loader from my service when the service update / delete data in the DB.
With the DI, I can easily get them in resolvers but I believe the services are the best place to hold such logic. However, I am not sure how to properly retrieve a loader in my service.

I checked how the @loader() decorator works and noticed it uses an internal store not available outside the DataloaderModule, so I understand I can't rely on it.

Would you be able to help? :)

[robertrossmann]

Hi @GauthierPLM , yes, this is currently not possible as part of this module's design. The easiest and probably most effective approach would be to pass the dataloader instance into the service as a parameter, or provide some kind of mechanism for the service to notify the resolver that a specific object should be purged from the cache. For example, an event emitter instance might be passed to the service and the resolver could listen for a specific event to purge that item from the dataloader.

I thought about incorporating a purge mechanism into the module itself and while it could be made part of the DataloaderFactory class' API, the factory would have to purge the item from all instances of Dataloader it created. This may or may not be desirable, as a Dataloader instance is created for each individual request. You could then purge an item from the cache for all pending requests, not just the one that caused the update.