Liferay Document Library: execute method on document download

Question

I've asked the same question in Liferay community but with no answers so I try here :)

I need to perform an action/call a method everytime a user download a file from the document library, for simplicity I'd say a System.out.println("a file has been downloaded") everytime the user click on the direct file link.

Do you have any idea on how I can achieve this? I'm using LR 6.0.6 CE and would really try to avoid the EXT environment... any idea on how to achieve this with a hook would be much appreciated!!

I was thinking about adding some javascript on the JSP (onClick) that calls the System.out.println() function, but not sure if it's possible.

I thought about action hooks, model listeners, override a service... what do you think would be the best way?

Answer 1

I've found a way to achieve this creating a model Listener for the DLFileEntry model and overriding the method "onAfterUpdate", which is triggered every time a document is downloaded because it changes the value of the readcount variable.

Answer 2

In order to add business logic, you should rather look at DLFileEntryLocalService and the wrappers for this service, instead of model listeners. Model Listeners are meant for persistence-related fixes, but not to add arbitrary new logic - that's what's better in *LocalService wrappers, as *LocalService is all about business logic.

This requires a Hook, you're right to keep away from ext - it's not required here and you'd have more upgrade issues than with a hook.