Support for Criteria equivalent based queries like JpaSpecificationExecutor

[rcpacheco]

Support for Criteria equivalent funtionality to do queries like JpaSpecificationExecutor.
Being a user of spring data jpa, we use a lot the Specification based queries to implement
paging, sort, search and filter funtionality in our apps. Having a similar capability would make the migration to r2dbc easier.

[guillaumelamirand]

Hi,

I agree with this. How could use queries like JpaSpecificationExecutor with spring data r2dbc ? I tried to mix data jpa and data r2dbc only for pagination queries but the application won't start. Do you have an ETA for that feature ?

Thanks

[mp911de]

I'm not sure we want to introduce such a feature in the first place. R2dbcEntityTemplate exposes exactly what you're looking for. What's wrong with using R2dbcEntityTemplate.select(Query, Class)?

[guillaumelamirand]

Yes of course but from my point of view it is also the purpose of a Repository to offer those kind of features. First of all because it is easier to use and also it is how we already use it with standard JPA implementation.

Why don't you want to add such feature? How whould we with r2dbc repository manage pagination and search ?

[mp911de]

You can use Pageable and Sort with query derivation. Alternatively, you can use @Query to specify your query.

Again, what's wrong with using R2dbcEntityTemplate.select(Query, Class)?

[guillaumelamirand]

In fact we are not using Query but Predicate coming from a built Specification, not sure R2dbcEntityTemplate.select(Query, Class) can solve this.

[mp911de]

Note that Spring Data R2DBC doesn't use JPA API hence there's no support for javax.persistence.criteria.Predicate.

[guillaumelamirand]

Ok, that confirm what I suspected. Does it mean I cannot use criteria api with R2dbc?

[mp911de]

There's org.springframework.data.relational.core.query.Criteria which is obviously different from the JPA Criteria type. However, they work similar and I'd argue that org.springframework.data.relational.core.query.Criteria is simpler to use.

[guillaumelamirand]

We are building a complex specification from a search param given by user to request what he wants. He gives us sth like "/topics?search=type:toto AND channel.user?" and we transform that into a Speficiation used to request the db.

I will have a look if org.springframework.data.relational.core.query.Criteria can be used the same way.
Thanks any way for helping.

[rcpacheco]

We have the same situation, using specs to filter data from grids makes our work more Easy.

[guillaumelamirand]

@mp911de Sorry for the delay. I did take the time today to look into R2dbcEntityTemplate, Query and Criteria but from what I understand query doesn't manage entities relationship (join, left join, etc) so how could I use it with a complex query joining multiple table ?

[mp911de]

That is generally true for Spring Data R2DBC, we don't support relationships yet.

[guillaumelamirand]

@mp911de ok . Is it something plan for future release?