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One-To-Many Reference is null - But shouldn't be null

See original GitHub issue

I have two tables:

User:

object Users : IntIdTable("users") {
    val firstName = varchar("first_name", 64)
    val lastName = varchar("last_name", 64)
}

class UserEntity(id: EntityID<Int>) : IntEntity(id) {
    companion object : IntEntityClass<UserEntity>(Users)

    var firstName by Users.firstName
    var lastName by Users.lastName
    val permissions by UserPermissionEntity referrersOn UserPermissions.user
}

UserPermissions:

object UserPermissions : IntIdTable("user_permissions") {
    val user: Column<EntityID<Int>> = reference("user_id", Users.id)
    val permission = integer("permission")
}

class UserPermissionEntity(id: EntityID<Int>) : IntEntity(id) {
    companion object : IntEntityClass<UserPermissionEntity>(UserPermissions)

    var user by UserEntity referencedOn UserPermissions.user
    var permission by UserPermissions.permission
}

Now, when I query a User (e.G. UserEntity.findById(1)) and want to access the permissions, I get following exception:

java.lang.NullPointerException: null
	at de.todonxt.api.endpoints.user.UserEndpointsKt$userRoute$3.invokeSuspend(UserEndpoints.kt:84)
	at de.todonxt.api.endpoints.user.UserEndpointsKt$userRoute$3.invoke(UserEndpoints.kt)
	at de.todonxt.api.endpoints.user.UserEndpointsKt$userRoute$3.invoke(UserEndpoints.kt)
	at io.ktor.server.resources.RoutingKt$handle$2.invokeSuspend(Routing.kt:197)
	at io.ktor.server.resources.RoutingKt$handle$2.invoke(Routing.kt)
	at io.ktor.server.resources.RoutingKt$handle$2.invoke(Routing.kt)
	at io.ktor.server.routing.Route$buildPipeline$1$1.invokeSuspend(Route.kt:116)
	at io.ktor.server.routing.Route$buildPipeline$1$1.invoke(Route.kt)
	at io.ktor.server.routing.Route$buildPipeline$1$1.invoke(Route.kt)
	at io.ktor.util.pipeline.SuspendFunctionGun.loop(SuspendFunctionGun.kt:123)
	at io.ktor.util.pipeline.SuspendFunctionGun.proceed(SuspendFunctionGun.kt:81)
	at io.ktor.util.pipeline.SuspendFunctionGun.execute$ktor_utils(SuspendFunctionGun.kt:101)
	at io.ktor.util.pipeline.Pipeline.execute(Pipeline.kt:77)
	at io.ktor.server.routing.Routing$executeResult$$inlined$execute$1.invokeSuspend(Pipeline.kt:478)
	at io.ktor.server.routing.Routing$executeResult$$inlined$execute$1.invoke(Pipeline.kt)
	at io.ktor.server.routing.Routing$executeResult$$inlined$execute$1.invoke(Pipeline.kt)
	at io.ktor.util.debug.ContextUtilsKt.initContextInDebugMode(ContextUtils.kt:17)
	at io.ktor.server.routing.Routing.executeResult(Routing.kt:174)
	at io.ktor.server.routing.Routing.interceptor(Routing.kt:49)
	at io.ktor.server.routing.Routing$Plugin$install$1.invokeSuspend(Routing.kt:124)
	at io.ktor.server.routing.Routing$Plugin$install$1.invoke(Routing.kt)
	at io.ktor.server.routing.Routing$Plugin$install$1.invoke(Routing.kt)
	at io.ktor.util.pipeline.SuspendFunctionGun.loop(SuspendFunctionGun.kt:123)
	at io.ktor.util.pipeline.SuspendFunctionGun.proceed(SuspendFunctionGun.kt:81)
	at io.ktor.server.engine.BaseApplicationEngineKt$installDefaultTransformationChecker$1.invokeSuspend(BaseApplicationEngine.kt:122)
	at io.ktor.server.engine.BaseApplicationEngineKt$installDefaultTransformationChecker$1.invoke(BaseApplicationEngine.kt)
	at io.ktor.server.engine.BaseApplicationEngineKt$installDefaultTransformationChecker$1.invoke(BaseApplicationEngine.kt)
	at io.ktor.util.pipeline.SuspendFunctionGun.loop(SuspendFunctionGun.kt:123)
	at io.ktor.util.pipeline.SuspendFunctionGun.proceed(SuspendFunctionGun.kt:81)
	at io.ktor.server.application.hooks.CallFailed$install$1$1.invokeSuspend(CommonHooks.kt:41)
	at io.ktor.server.application.hooks.CallFailed$install$1$1.invoke(CommonHooks.kt)
	at io.ktor.server.application.hooks.CallFailed$install$1$1.invoke(CommonHooks.kt)
	at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undispatched.kt:89)
	at kotlinx.coroutines.CoroutineScopeKt.coroutineScope(CoroutineScope.kt:264)
	at io.ktor.server.application.hooks.CallFailed$install$1.invokeSuspend(CommonHooks.kt:40)
	at io.ktor.server.application.hooks.CallFailed$install$1.invoke(CommonHooks.kt)
	at io.ktor.server.application.hooks.CallFailed$install$1.invoke(CommonHooks.kt)
	at io.ktor.util.pipeline.SuspendFunctionGun.loop(SuspendFunctionGun.kt:123)
	at io.ktor.util.pipeline.SuspendFunctionGun.proceed(SuspendFunctionGun.kt:81)
	at io.ktor.util.pipeline.SuspendFunctionGun.execute$ktor_utils(SuspendFunctionGun.kt:101)
	at io.ktor.util.pipeline.Pipeline.execute(Pipeline.kt:77)
	at io.ktor.server.engine.DefaultEnginePipelineKt$defaultEnginePipeline$1$invokeSuspend$$inlined$execute$1.invokeSuspend(Pipeline.kt:478)
	at io.ktor.server.engine.DefaultEnginePipelineKt$defaultEnginePipeline$1$invokeSuspend$$inlined$execute$1.invoke(Pipeline.kt)
	at io.ktor.server.engine.DefaultEnginePipelineKt$defaultEnginePipeline$1$invokeSuspend$$inlined$execute$1.invoke(Pipeline.kt)
	at io.ktor.util.debug.ContextUtilsKt.initContextInDebugMode(ContextUtils.kt:17)
	at io.ktor.server.engine.DefaultEnginePipelineKt$defaultEnginePipeline$1.invokeSuspend(DefaultEnginePipeline.kt:118)
	at io.ktor.server.engine.DefaultEnginePipelineKt$defaultEnginePipeline$1.invoke(DefaultEnginePipeline.kt)
	at io.ktor.server.engine.DefaultEnginePipelineKt$defaultEnginePipeline$1.invoke(DefaultEnginePipeline.kt)
	at io.ktor.util.pipeline.SuspendFunctionGun.loop(SuspendFunctionGun.kt:123)
	at io.ktor.util.pipeline.SuspendFunctionGun.proceed(SuspendFunctionGun.kt:81)
	at io.ktor.util.pipeline.SuspendFunctionGun.execute$ktor_utils(SuspendFunctionGun.kt:101)
	at io.ktor.util.pipeline.Pipeline.execute(Pipeline.kt:77)
	at io.ktor.server.netty.NettyApplicationCallHandler$handleRequest$1$invokeSuspend$$inlined$execute$1.invokeSuspend(Pipeline.kt:478)
	at io.ktor.server.netty.NettyApplicationCallHandler$handleRequest$1$invokeSuspend$$inlined$execute$1.invoke(Pipeline.kt)
	at io.ktor.server.netty.NettyApplicationCallHandler$handleRequest$1$invokeSuspend$$inlined$execute$1.invoke(Pipeline.kt)
	at io.ktor.util.debug.ContextUtilsKt.initContextInDebugMode(ContextUtils.kt:17)
	at io.ktor.server.netty.NettyApplicationCallHandler$handleRequest$1.invokeSuspend(NettyApplicationCallHandler.kt:119)
	at io.ktor.server.netty.NettyApplicationCallHandler$handleRequest$1.invoke(NettyApplicationCallHandler.kt)
	at io.ktor.server.netty.NettyApplicationCallHandler$handleRequest$1.invoke(NettyApplicationCallHandler.kt)
	at kotlinx.coroutines.intrinsics.UndispatchedKt.startCoroutineUndispatched(Undispatched.kt:55)
	at kotlinx.coroutines.CoroutineStart.invoke(CoroutineStart.kt:112)
	at kotlinx.coroutines.AbstractCoroutine.start(AbstractCoroutine.kt:126)
	at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch(Builders.common.kt:56)
	at kotlinx.coroutines.BuildersKt.launch(Unknown Source)
	at io.ktor.server.netty.NettyApplicationCallHandler.handleRequest(NettyApplicationCallHandler.kt:37)
	at io.ktor.server.netty.NettyApplicationCallHandler.channelRead(NettyApplicationCallHandler.kt:29)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
	at io.netty.channel.AbstractChannelHandlerContext.access$600(AbstractChannelHandlerContext.java:61)
	at io.netty.channel.AbstractChannelHandlerContext$7.run(AbstractChannelHandlerContext.java:370)
	at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
	at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:469)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:503)
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:986)
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
	at io.ktor.server.netty.EventLoopGroupProxy$Companion.create$lambda-1$lambda-0(NettyApplicationEngine.kt:263)
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
	at java.base/java.lang.Thread.run(Thread.java:832)

What is the problem? I don’t think that I missconfigured anything. Is it a bug?

Issue Analytics

State:
Created a year ago
Reactions:2
Comments:5 (1 by maintainers)

Top GitHub Comments

1reaction

orangethundercommented, May 19, 2022

@heli-os, it behaves this way even if I change it to Client.findById(id)!!.load(Client::feature_toggles).

I did some more googling and it turns out it’s a design limitation, see https://github.com/JetBrains/Exposed/issues/656#issuecomment-542113164. So I think this issue can be closed, but perhaps it would be better if an exception is thrown when trying to access an association outside of a transaction, rather than just returning null.

0reactions

thamiducommented, Jun 28, 2022

Just a guess. Can you make sure the User table has one row and that row has a UserPermission referenced, and then try again?

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