Possibility to LEFT JOIN FETCH for @EntityGraph [DATAJPA-1124]

[spring-projects-issues]

Yan Tuizhi opened DATAJPA-1124 and commented

Assuming I have the following entites

abstract House (rooms)  <- Shop extends House (shopWindows)

and a repository JpaRepository<House, Long>. If want to fetch all houses with all associations, this is currently not possbile with the @EntityGraph annotation. If i have the following method in the repository:

@EntityGraph(attributePaths = {"rooms", "shopWindows"})
@Query("FROM House")
Set<House> findAllWithDependencies()

then an exception will be thrown (shopWindows is not a property of House). However, if I set all assocations to FetchType.EAGER und use the findAll method, all Shop instances are found with all assocations.

It would be very helpful (especially for real world scenarios with complex inheritance relations), if the repository would automatically detect whether a given attributePath belongs to derived class and would in that case make a LEFT JOIN FETCH. This should also be possbile for all levels of association (e.g. in case there are different types of Room or ShopWindow).

My current workaround is the following:

@EntityGraph(attributePaths = {"rooms"})
@Query("FROM House H LEFT JOIN FETCH H.shopWindows")
Set<House> findAllWithDependencies()

Alternatively, I guess I could create a repository for each derived class, but that would duplicate a lot of code.

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Affects: 1.11.3 (Ingalls SR3)

[spring-projects-issues]

Jens Schauder commented

The entity graph doesn't match the query so the JPA implementation throws an exception.

Spring Data is not going to try to fix incompatible combinations of entity graph and query