Error when returning Vavr collection from @Query projection [DATACMNS-1611]

[spring-projects-issues]

Ruben Gees opened DATACMNS-1611 and commented

We get an error when trying to return a Vavr collection from a JpaRepository containing only parts of the object.

One example of such an interface method is:

@Query("SELECT name FROM Todo")
fun findAllNamesVavr(): Seq<String>

This crashes with the stack trace:

java.lang.ClassCastException: class java.lang.String cannot be cast to class io.vavr.collection.Seq (java.lang.String is in module java.base of loader 'bootstrap'; io.vavr.collection.Seq is in unnamed module of loader 'app')
	at com.sun.proxy.$Proxy84.findAllNamesVavr(Unknown Source)
	at com.example.demospringdatavavr.TodoRepositoryTest.finding names vavr seq(TodoRepositoryTest.kt:45)

  Reproduced starting with Spring Boot 2.1.0.RELEASE.

Reproduction project: https://github.com/rubengees/demo-spring-data-vavr

Run

./gradlew build 

We debugged into the relevant classes and found the QueryExecutionResultHandler to be a possible cause of this. It looked like the handler tries to convert the entire List (from hibernate) to the inner type (String) of the return Type (Seq<String>) instead of converting each inner element of the List (from hibernate)

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Affects: 2.2.1 (Moore SR1)

1 votes, 2 watchers

[dkraemerwork]

This is still an issue!

[odrotbohm]

This shouldn't be the case on recent versions? If someone was willing to make the example work with a recent Boot / Gradle version (I spent 30 minutes on that but was unable to get it to work), I'm willing to investigate.