Please provide example for using ReactiveEvaluationContextProvider

[RobertHeim]

As I notice from the blog entry it should be possible to put stuff on the context for SpEL expressions, but I was not able to implement it.

@Configuration
class MyConfig {
  class X : EvaluationContextExtension{
    override fun getRootObject(): Any? {
      return "de"
    }
    override fun getExtensionId(): String {
      return "myExtension"
    }
  }

  class Y : ReactiveEvaluationContextExtension {
    override fun getExtensionId(): String {
      return "myExtension"
    }

    override fun getExtension(): Mono<out EvaluationContextExtension> {
      return  Mono.just(X())
    }
  }
  @Bean
  fun reactiveEvaluationContextExtension() : ReactiveEvaluationContextExtension? {
    return Y()
  }
}

When using it in a @Query like this:

interface TaskRepository : CoroutineCrudRepository<Task, Long> {
  @Query("SELECT * FROM task t WHERE t.locale = ?#{myExtension}")
  fun findWithLocale(): Flow<Task>
}

I see

EL1008E: Property or field 'myExtension' cannot be found on object of type 'java.lang.Object[]' - maybe not public or not valid?

In the end I would like to access the request's locale without putting it as a parameter to all controllers and services, e.g.

@Query("... WHERE tl10n.locale = ?#{locale.language}"

[mp911de]

Take a look at https://github.com/spring-projects/spring-data-mongodb/blob/ad6d2c97b7b03e14fe3233509fd13588fc33db92/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/repository/query/ReactiveStringBasedMongoQueryUnitTests.java#L306-L338.