Document "SpEl support in @Query" feature as a breaking change

[MaartenTutak]

Hi,

I just noticed one of our integration tests failing after upgrading Spring Boot from 3.2.6 to 3.3.1
It seems #2826 (intentionally) added a breaking change regarding the handling of null values in the context of the @Query annotation. While I have no specific opinion on this change, I did notice it is not documented as a breaking change on any resource I can find. In our case specifically, we went from receiving an HTTP 200 response from ES containing no hits to having a ConversionException thrown.

Kind regards,
Maarten Tutak

[sothawo]

Hm, thanks for this hint. Can you provide an example of what worked before and is breaking now. Not sure, if this behavioural change should have been.

[MaartenTutak]

Hi,

sure thing.

https://github.com/MaartenTutak/spring-data-elasticsearch-2936/tree/spring-boot-3.2.6
https://github.com/MaartenTutak/spring-data-elasticsearch-2936/tree/spring-boot-3.3.1

FooRepositoryIntegrationTest works on 3.2.6, but not on 3.3.1

Thanks,
Maarten

[sothawo]

Thank you for the sample code.

You are right, this breaking change should have been documented, we missed that. I updated the migration guide from version 5.2 to 5.3 to include this information (8d0ecf2).

As for the reason to change that behaviour: Up to version 5.2 when a null parameter was encountered this was replaced with the string "null" in the query. Your test with Boot 3.2.6 would fail as well if you change your setup to:

    @BeforeEach
    void setUp() {
        fooRepository.save(new Foo(UUID.randomUUID(), "Foo", "null"));
    }

because now the search fooRepository.findBy("Foo", null) would return the one entity stored in the index. This only makes sense when "null" was defined as the null_value in the Elasticsearch field mapping (which it isn't in your case). And to search for the null_value now the user needs to explicitly call fooRepository.findBy("Foo", "null").

Further docs about null values: https://www.elastic.co/guide/en/elasticsearch/guide/current/_dealing_with_null_values.html

[puppylpg]

This situation was stated in #2833 :

Another problem is that when using placeholder(?0, ?1...) in @Query, null value will be converted to string "null", and this should be considered a bug as stated in #2826 (comment). The simplest way to deal with that is to use the new ConversionService in StringQueryUtil, since the conversion logic has already been well handled in ConversionService.

• propose2: replece the old logic for values conversion in StringQueryUtil;

It should have been added into breaking-change docs. 👍