Use Entity Graph with projections

[z8manu8z]

Hello all,

I try to use Cosium Entity Graph library with JPA projections (https://docs.spring.io/spring-data/jpa/reference/repositories/projections.html) but I get an InapplicableEntityGraphException.
It seems that the only type possible for repositories methods is model class (defined in EntityGraphJpaRepository<ModelClass, Long>).
Any idea on how to return interfaces ?

Thanks !

[reda-alaoui]

Under the hood, spring-data-jpa projections lead to multi select JPA queries which are not compatible with JPA EntityGraph. You can't have both.

[z8manu8z]

Thanks for your quick reply,

I currently use JPA projections in combination with JPA entity graphs.
For example to retrieve a Product object with or without the list of corresponding Orders.
This works great and allows me to retrieve the entire tree with a single query.
The major disadvantage is that the graphs used are static and therefore do not allow me to have a single method with a parameter allowing me to retrieve orders for a product or not.

[reda-alaoui]

I currently use JPA projections in combination with JPA entity graphs.
For example to retrieve a Product object with or without the list of corresponding Orders.

I think your EntityGraph annotation is, at best, just ignored by spring-data-jpa.

See:

• Closed Projection does not work with @EntityGraph [DATAJPA-1501] spring-projects/spring-data-jpa#1814
• I need some clarification on using a Repository function with projection interface and @EntityGraph spring-projects/spring-data-jpa#2709

[z8manu8z]

It's strange ...
I am simply basing this on the fact that my query using JPA projections does not have the same effect with or without the graph: N+1 queries without, only 1 query with it.