Spring cacheable - filter out empty collections using SpEL

Question

I wanted to know is there a way to use SpEL in order to filter out values like empty collections.

My cache currently filters out null values:

  @Cacheable(value = "groupIdToGroupNames",unless = "#result == null")
   public Map<Long, Collection<String>> findAllBySearchCustomerKey(final long groupId) {
    return idToNameClient.findAllGroupMembersById(groupId);
   }

I'm trying to find a way to filter out the groups that are of size 0 but not null. Is there a way of doing that by using params for @Cacheable?

Any help would be much appreciated.

score 49 · Accepted Answer · edited Jun 07 '22 at 04:49

49

Something like this

unless = "#result==null or #result.size()==0"

More about result and or.

edited Jun 07 '22 at 04:49

jumping_monkey

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answered Sep 22 '14 at 15:29

Artem Bilan

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I just added it. Newbe to SpEL:) Thanks! – user2512231 Sep 22 '14 at 15:43

score 18 · Answer 2 · answered Feb 15 '19 at 10:05

18

unless = "#result==null or #result.isEmpty()" works for me.

answered Feb 15 '19 at 10:05

NanoNova

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This does not seem to add anything new over the accepted 5 year old answer. It will probably be deleted by reviewers. If you think your answer makes a significant difference, you may want to add an explanation on how this is better than the existing answers. – nvoigt Feb 15 '19 at 10:40
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probably this was more readable to me instead of #result.size()==0. Also agree with @nvoigt that we should add explanation over any answer. – SUMIT May 22 '19 at 18:25
adds plenty! a method `isEmpty` may end up doing something more than a simple check, and is worth it for readability as well – Brad Parks Oct 23 '20 at 11:40

score 0 · Answer 3 · answered Dec 06 '17 at 20:16

Just to show an example (Artem Bilan answer is the valid one). My function can return Optional.ofEmpty or Optional of my object

@Cacheable(value = "myCache", unless = "#result == null", key = "@myDao.cacheKey(#id, #languageCode)")
public Optional<MyDTO> getMyStuff(int id, String languageCode) {
... }

score 0 · Answer 4 · answered Sep 16 '21 at 01:48

0

This worked for me

@Cacheable(cacheNames = "recordCache", key = "#list", unless="#result == null or #result.size() == 0")

answered Sep 16 '21 at 01:48

David AJ

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Spring cacheable - filter out empty collections using SpEL

4 Answers4