Add `unless` option to Cacheable

[igoraguiar]

I have some cache conditions where the value can only be cached if the value is not null. Apparently there is now way to do it in version 4, since the result of the method call can not be accessed inside the condition closure.

Before, I had the following condition: "#result != null", now I would need to rewrite it to something like { result != null }

[jameskleeh]

I don't understand the use case. Can you put together a more concrete example?

[igoraguiar]

Of course. I have a service with a method like this:

@Cacheable(value = "dataServiceCache.vehicleByLabelAndCompanyId", condition = "#result != null") Vehicle findVehicleByLabelAndCompanyId(String label, long companyId) {

}

Now, with version 4, I have no way to do it using the condition closure. I don't want to cache null values because, in the exemple, the vehicle may be inserted at some point, and the method will continue to return null.

Also, IMHO, I think it should be nice to keep this kind of compatibility with the previous version.

[kgeis]

This could help with transitioning to newer versions of Grails that use ehcache 3. Version 2 allows null values, but 3 does not.

I think that Grails' Cacheable should try to follow Spring's. The solution would therefore be to add unless to mirror Spring's unless, in which "Unlike condition(), this expression is evaluated after the method has been called and can therefore refer to the result."

[SleepingForester]

The problem wasn't solved. If somebody came here with the same problem: solution that works for me is to override Ehcache.java file and add if(value == null) { putObserver.end(PutOutcome.NOOP); } Into put method