我在结合使用 Kotlin、SpringBoot 2.0 和 MongoDB(带有 Spring Data)以及 @Transient 的项目中遇到问题。首先，这是我声明数据类的方式
@Document data class Child(@Id val id: String?, val name: String)
@Document data class Parent(@Id val id: String?, val child: Child? = null, val childId: String)
我知道可能有更好的方法从 Parent 引用 Child，但 MongoDB 是现有的。
这里的问题是，我不想在 Parent 中保留 child 属性，所以我尝试用 kotlin.jvm 注释该属性。 Transient，或 org.springframework.data.annotation.Transient，或两者。但是似乎没有任何组合可以解决我的问题。我面临的问题是:
- 当我使用
kotlin.jvm.Transient时，它正在加载，但是当我将它保存回来时，它会与它一起保留child属性 - 当我使用
org.springframework.data.annotation.Transient时，无法使用堆栈跟踪读取:
org.springframework.data.mapping.MappingException: No property child found on entity class com.example.sample.domain.Parent to bind constructor parameter to!
at org.springframework.data.mapping.model.PersistentEntityParameterValueProvider.getParameterValue(PersistentEntityParameterValueProvider.java:68)
at org.springframework.data.mapping.model.SpELExpressionParameterValueProvider.getParameterValue(SpELExpressionParameterValueProvider.java:49)
at org.springframework.data.convert.ClassGeneratingEntityInstantiator$EntityInstantiatorAdapter.extractInvocationArguments(ClassGeneratingEntityInstantiator.java:250)
at org.springframework.data.convert.ClassGeneratingEntityInstantiator$EntityInstantiatorAdapter.createInstance(ClassGeneratingEntityInstantiator.java:223)
at org.springframework.data.convert.ClassGeneratingEntityInstantiator.createInstance(ClassGeneratingEntityInstantiator.java:84)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:272)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:245)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:194)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:190)
at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:78)
at org.springframework.data.mongodb.core.ReactiveMongoTemplate$ReadDocumentCallback.doWith(ReactiveMongoTemplate.java:2920)
at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:100)
at reactor.core.publisher.MonoNext$NextSubscriber.onNext(MonoNext.java:76)
at com.mongodb.reactivestreams.client.internal.ObservableToPublisher$1.onNext(ObservableToPublisher.java:68)
at com.mongodb.async.client.AbstractSubscription.onNext(AbstractSubscription.java:135)
at com.mongodb.async.client.AbstractSubscription.processResultsQueue(AbstractSubscription.java:203)
at com.mongodb.async.client.AbstractSubscription.tryProcessResultsQueue(AbstractSubscription.java:159)
at com.mongodb.async.client.SingleResultCallbackSubscription$1.onResult(SingleResultCallbackSubscription.java:48)
at com.mongodb.async.client.FindIterableImpl$1$1.onResult(FindIterableImpl.java:213)
at com.mongodb.async.client.FindIterableImpl$1$1.onResult(FindIterableImpl.java:204)
at com.mongodb.operation.AsyncQueryBatchCursor.next(AsyncQueryBatchCursor.java:136)
at com.mongodb.operation.AsyncQueryBatchCursor.next(AsyncQueryBatchCursor.java:100)
at com.mongodb.async.client.FindIterableImpl$1.onResult(FindIterableImpl.java:204)
at com.mongodb.async.client.FindIterableImpl$1.onResult(FindIterableImpl.java:198)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.async.client.OperationExecutorImpl$1$1.onResult(OperationExecutorImpl.java:82)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.operation.FindOperation$3.onResult(FindOperation.java:806)
at com.mongodb.operation.OperationHelper$ReferenceCountedReleasingWrappedCallback.onResult(OperationHelper.java:364)
at com.mongodb.operation.CommandOperationHelper$2.onResult(CommandOperationHelper.java:405)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.internal.connection.DefaultServer$DefaultServerProtocolExecutor$2.onResult(DefaultServer.java:227)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.internal.connection.CommandProtocolImpl$1.onResult(CommandProtocolImpl.java:85)
at com.mongodb.internal.connection.DefaultConnectionPool$PooledConnection$1.onResult(DefaultConnectionPool.java:461)
at com.mongodb.internal.connection.UsageTrackingInternalConnection$2.onResult(UsageTrackingInternalConnection.java:111)
at com.mongodb.internal.async.ErrorHandlingResultCallback.onResult(ErrorHandlingResultCallback.java:49)
at com.mongodb.internal.connection.InternalStreamConnection$2$1.onResult(InternalStreamConnection.java:379)
at com.mongodb.internal.connection.InternalStreamConnection$2$1.onResult(InternalStreamConnection.java:356)
at com.mongodb.internal.connection.InternalStreamConnection$MessageHeaderCallback$MessageCallback.onResult(InternalStreamConnection.java:651)
at com.mongodb.internal.connection.InternalStreamConnection$MessageHeaderCallback$MessageCallback.onResult(InternalStreamConnection.java:618)
at com.mongodb.internal.connection.InternalStreamConnection$5.completed(InternalStreamConnection.java:494)
at com.mongodb.internal.connection.InternalStreamConnection$5.completed(InternalStreamConnection.java:491)
at com.mongodb.connection.netty.NettyStream.readAsync(NettyStream.java:236)
at com.mongodb.internal.connection.InternalStreamConnection.readAsync(InternalStreamConnection.java:491)
at com.mongodb.internal.connection.InternalStreamConnection.access$1000(InternalStreamConnection.java:74)
at com.mongodb.internal.connection.InternalStreamConnection$MessageHeaderCallback.onResult(InternalStreamConnection.java:608)
at com.mongodb.internal.connection.InternalStreamConnection$MessageHeaderCallback.onResult(InternalStreamConnection.java:593)
at com.mongodb.internal.connection.InternalStreamConnection$5.completed(InternalStreamConnection.java:494)
at com.mongodb.internal.connection.InternalStreamConnection$5.completed(InternalStreamConnection.java:491)
at com.mongodb.connection.netty.NettyStream.readAsync(NettyStream.java:236)
at com.mongodb.connection.netty.NettyStream.handleReadResponse(NettyStream.java:266)
at com.mongodb.connection.netty.NettyStream.access$600(NettyStream.java:66)
at com.mongodb.connection.netty.NettyStream$InboundBufferHandler.channelRead0(NettyStream.java:325)
at com.mongodb.connection.netty.NettyStream$InboundBufferHandler.channelRead0(NettyStream.java:322)
at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1434)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:965)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:648)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:583)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:500)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:462)
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:897)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:844)
- 当我同时使用这两个注释时，它的结果与 #1 相同(很明显)，因为应用程序在尝试执行某些逻辑之前正在读取数据。
非常感谢任何帮助
最佳答案
添加一个新的 kotlin 构造函数并给它注解 @PersistenceConstructor
关于mongodb - 带有 Kotlin 的 spring-data-mongodb 上的 @Transient 在读取期间导致异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/54145730/