Reactive Mongo - DeleteAllBy… query - Couldn't find PersistentEntity for type class java.lang.Void

Question

Hi I have a spring boot webflux app and use mongo db as a backend. I want to remove all documents that match a certain query so I created a method

fun deleteAllByInsertTimestampIsBefore(to: LocalDateTime): Mono<Void>

However when I want to execute the method I get an exception

reactor.core.Exceptions$ErrorCallbackNotImplemented: org.springframework.data.mapping.MappingException: Couldn't find PersistentEntity for type class java.lang.Void!
Caused by: org.springframework.data.mapping.MappingException: Couldn't find PersistentEntity for type class java.lang.Void!
    at org.springframework.data.mapping.context.MappingContext.getRequiredPersistentEntity(MappingContext.java:79)
    at org.springframework.data.mongodb.repository.query.DtoInstantiatingConverter.<init>(DtoInstantiatingConverter.java:62)
    at org.springframework.data.mongodb.repository.query.ReactiveMongoQueryExecution$ResultProcessingConverter.convert(ReactiveMongoQueryExecution.java:176)
    at org.springframework.data.mongodb.repository.query.ReactiveMongoQueryExecution$ResultProcessingExecution.execute(ReactiveMongoQueryExecution.java:146)
    at org.springframework.data.mongodb.repository.query.AbstractReactiveMongoQuery.execute(AbstractReactiveMongoQuery.java:125)
    at org.springframework.data.mongodb.repository.query.AbstractReactiveMongoQuery.execute(AbstractReactiveMongoQuery.java:91)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:605)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$invoke$3(RepositoryFactorySupport.java:595)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:595)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.repository.core.support.MethodInvocationValidator.invoke(MethodInvocationValidator.java:99)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
    at com.sun.proxy.$Proxy91.deleteAllByInsertTimestampIsBefore(Unknown Source)
    at com.x.sniper.app.registration.RegistrationRequestService.removeOldRegistrationRequest(RegistrationRequestService.kt:56)
    at com.x.sniper.app.registration.SpringRegistrationService.removeOldRegistrationRequest(SpringRegistrationService.kt:76)
    at com.x.sniper.app.database.ScheduledDatabaseCleanup$setup$1.invoke(ScheduledDatabaseCleanup.kt:32)
    at com.x.sniper.app.database.ScheduledDatabaseCleanup$setup$1.invoke(ScheduledDatabaseCleanup.kt:17)
    at com.x.sniper.app.database.ScheduledDatabaseCleanup$scheduledDatabaseCleanup$3.apply(ScheduledDatabaseCleanup.kt:47)
    at com.x.sniper.app.database.ScheduledDatabaseCleanup$scheduledDatabaseCleanup$3.apply(ScheduledDatabaseCleanup.kt:17)
    at reactor.core.publisher.FluxFlatMap$FlatMapMain.onNext(FluxFlatMap.java:350)
    at reactor.core.publisher.FluxFlatMap$FlatMapMain.drainLoop(FluxFlatMap.java:664)
    at reactor.core.publisher.FluxFlatMap$FlatMapMain.drain(FluxFlatMap.java:540)
    at reactor.core.publisher.FluxFlatMap$FlatMapInner.onSubscribe(FluxFlatMap.java:924)
    at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:139)
    at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:63)
    at reactor.core.publisher.Flux.subscribe(Flux.java:7921)
    at reactor.core.publisher.FluxFlatMap$FlatMapMain.onNext(FluxFlatMap.java:389)
    at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:192)
    at reactor.core.publisher.FluxInterval$IntervalRunnable.run(FluxInterval.java:123)
    at reactor.core.scheduler.PeriodicWorkerTask.call(PeriodicWorkerTask.java:59)
    at reactor.core.scheduler.PeriodicWorkerTask.run(PeriodicWorkerTask.java:73)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

Does it mean that spring data DeleteBy.. methods return something different than Mono

Answer 1

Reactive SpringData deleteBy queries can emit either the number of Documents deleted, or the deleted entities themselves, like in the snippet below.

fun deleteAllByLastname(lastname: String): Mono<Long>
fun deleteAllByLastname(lastname: String): Flux<Person> 

In case you're just interested in the completion signal please use then() to turn the result in to Mono<Void> .

I created DATAMONGO-2406 to improve the behavior of deleteBy .