NullPointerException when creating sub mapping method between an array and another type

[lex-em]

Hi, how I can pass target mapping object to custom mapping method as parameter?
I am trying something like this, but take NPE during compilation:

@Mapper(uses = {AddressMapper.class}, componentModel = "spring")
public abstract class ApplicationMapper {

    @Mappings({
            ...
    })
    public abstract Application applicationFromDto(ApplicationDto applicationDto);

    public Set<SomeType> convertScanCopy(byte[][] datas, @MappingTarget Application application) {
        return Arrays.stream(datas).map(data -> {
            SomeTypes obj= new SomeType();
            obj.setData(data);
            obj.setApplication(application);
            return obj;
        }).collect(Collectors.toSet());
    }
}

Internal error in the mapping processor: java.lang.NullPointerException
  	at org.mapstruct.ap.internal.util.workarounds.SpecificCompilerWorkarounds.replaceTypeElementIfNecessary(SpecificCompilerWorkarounds.java:112)
  	at org.mapstruct.ap.internal.util.Executables.getAllEnclosedAccessors(Executables.java:208)
  	at org.mapstruct.ap.internal.model.common.Type.getAllAccessors(Type.java:528)
  	at org.mapstruct.ap.internal.model.common.Type.getPropertyReadAccessors(Type.java:391)
  	at org.mapstruct.ap.internal.model.BeanMappingMethod$Builder.applyPropertyNameBasedMapping(BeanMappingMethod.java:538)
  	at org.mapstruct.ap.internal.model.BeanMappingMethod$Builder.build(BeanMappingMethod.java:145)
  	at org.mapstruct.ap.internal.model.AbstractBaseBuilder.createForgedAssignment(AbstractBaseBuilder.java:80)
  	at org.mapstruct.ap.internal.model.AbstractMappingMethodBuilder.forgeMapping(AbstractMappingMethodBuilder.java:76)
  	at org.mapstruct.ap.internal.model.ContainerMappingMethodBuilder.build(ContainerMappingMethodBuilder.java:107)
  	at org.mapstruct.ap.internal.model.PropertyMapping$PropertyMappingBuilder.forgeWithElementMapping(PropertyMapping.java:597)
  	at org.mapstruct.ap.internal.model.PropertyMapping$PropertyMappingBuilder.forgeIterableMapping(PropertyMapping.java:584)
  	at org.mapstruct.ap.internal.model.PropertyMapping$PropertyMappingBuilder.build(PropertyMapping.java:278)
  	at org.mapstruct.ap.internal.model.BeanMappingMethod$Builder.applyPropertyNameBasedMapping(BeanMappingMethod.java:569)
  	at org.mapstruct.ap.internal.model.BeanMappingMethod$Builder.build(BeanMappingMethod.java:145)
  	at org.mapstruct.ap.internal.processor.MapperCreationProcessor.getMappingMethods(MapperCreationProcessor.java:373)
  	at org.mapstruct.ap.internal.processor.MapperCreationProcessor.getMapper(MapperCreationProcessor.java:152)
  	at org.mapstruct.ap.internal.processor.MapperCreationProcessor.process(MapperCreationProcessor.java:123)
  	at org.mapstruct.ap.internal.processor.MapperCreationProcessor.process(MapperCreationProcessor.java:80)
  	at org.mapstruct.ap.MappingProcessor.process(MappingProcessor.java:280)
  	at org.mapstruct.ap.MappingProcessor.processMapperTypeElement(MappingProcessor.java:260)
  	at org.mapstruct.ap.MappingProcessor.processMapperElements(MappingProcessor.java:226)
  	at org.mapstruct.ap.MappingProcessor.process(MappingProcessor.java:162)
  	at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:794)
  	at com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:705)
  	at com.sun.tools.javac.processing.JavacProcessingEnvironment.access$1800(JavacProcessingEnvironment.java:91)
  	at com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1035)
  	at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1176)
  	at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1170)
  	at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:856)
  	at com.sun.tools.javac.main.Main.compile(Main.java:523)
  	at com.sun.tools.javac.api.JavacTaskImpl.doCall(JavacTaskImpl.java:129)
  	at com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:138)
  	at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJavaCompiler.java:46)
  	at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJavaCompiler.java:33)
  	at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.delegateAndHandleErrors(NormalizingJavaCompiler.java:99)
  	at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute(NormalizingJavaCompiler.java:52)
  	at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute(NormalizingJavaCompiler.java:37)
  	at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.execute(CleaningJavaCompilerSupport.java:35)
  	at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.execute(CleaningJavaCompilerSupport.java:25)
  	at org.gradle.api.tasks.compile.JavaCompile.performCompilation(JavaCompile.java:244)
  	at org.gradle.api.tasks.compile.JavaCompile.compile(JavaCompile.java:229)
  	at org.gradle.api.tasks.compile.JavaCompile.compile(JavaCompile.java:151)
  	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
  	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  	at java.lang.reflect.Method.invoke(Method.java:498)
  	at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73)
  	at org.gradle.api.internal.project.taskfactory.DefaultTaskClassInfoStore$IncrementalTaskAction.doExecute(DefaultTaskClassInfoStore.java:163)
  	at org.gradle.api.internal.project.taskfactory.DefaultTaskClassInfoStore$StandardTaskAction.execute(DefaultTaskClassInfoStore.java:134)
  	at org.gradle.api.internal.project.taskfactory.DefaultTaskClassInfoStore$StandardTaskAction.execute(DefaultTaskClassInfoStore.java:123)
  	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$1.execute(ExecuteActionsTaskExecuter.java:115)
  	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$1.execute(ExecuteActionsTaskExecuter.java:109)
  	at org.gradle.internal.Transformers$4.transform(Transformers.java:169)
  	at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:106)
  	at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:56)
  	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:109)
  	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:90)
  	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:68)
  	at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:62)
  	at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
  	at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:88)
  	at org.gradle.api.internal.tasks.execution.ResolveTaskArtifactStateTaskExecuter.execute(ResolveTaskArtifactStateTaskExecuter.java:46)
  	at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:51)
  	at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:54)
  	at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
  	at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:34)
  	at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker$1.execute(DefaultTaskGraphExecuter.java:236)
  	at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker$1.execute(DefaultTaskGraphExecuter.java:228)
  	at org.gradle.internal.Transformers$4.transform(Transformers.java:169)
  	at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:106)
  	at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:61)
  	at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:228)
  	at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:215)
  	at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.processTask(AbstractTaskPlanExecutor.java:77)
  	at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.run(AbstractTaskPlanExecutor.java:58)
  	at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(DefaultTaskPlanExecutor.java:32)
  	at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:113)
  	at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:37)
  	at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37)
  	at org.gradle.execution.DefaultBuildExecuter.access$000(DefaultBuildExecuter.java:23)
  	at org.gradle.execution.DefaultBuildExecuter$1.proceed(DefaultBuildExecuter.java:43)
  	at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)
  	at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37)
  	at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:30)
  	at org.gradle.initialization.DefaultGradleLauncher$RunTasksAction.execute(DefaultGradleLauncher.java:230)
  	at org.gradle.initialization.DefaultGradleLauncher$RunTasksAction.execute(DefaultGradleLauncher.java:227)
  	at org.gradle.internal.Transformers$4.transform(Transformers.java:169)
  	at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:106)
  	at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:56)
  	at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:161)
  	at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:112)
  	at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:95)
  	at org.gradle.launcher.exec.GradleBuildController.run(GradleBuildController.java:66)
  	at org.gradle.tooling.internal.provider.runner.BuildModelActionRunner.run(BuildModelActionRunner.java:50)
  	at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
  	at org.gradle.tooling.internal.provider.runner.RunAsBuildOperationBuildActionRunner$1.execute(RunAsBuildOperationBuildActionRunner.java:43)
  	at org.gradle.tooling.internal.provider.runner.RunAsBuildOperationBuildActionRunner$1.execute(RunAsBuildOperationBuildActionRunner.java:40)
  	at org.gradle.internal.Transformers$4.transform(Transformers.java:169)
  	at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:106)
  	at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:56)
  	at org.gradle.tooling.internal.provider.runner.RunAsBuildOperationBuildActionRunner.run(RunAsBuildOperationBuildActionRunner.java:40)
  	at org.gradle.tooling.internal.provider.runner.SubscribableBuildActionRunner.run(SubscribableBuildActionRunner.java:88)
  	at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
  	at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:41)
  	at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:26)
  	at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:75)
  	at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:49)
  	at org.gradle.tooling.internal.provider.ServicesSetupBuildActionExecuter.execute(ServicesSetupBuildActionExecuter.java:49)
  	at org.gradle.tooling.internal.provider.ServicesSetupBuildActionExecuter.execute(ServicesSetupBuildActionExecuter.java:31)
  	at org.gradle.launcher.daemon.server.exec.ExecuteBuild.doBuild(ExecuteBuild.java:67)
  	at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36)
  	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
  	at org.gradle.launcher.daemon.server.exec.WatchForDisconnection.execute(WatchForDisconnection.java:37)
  	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
  	at org.gradle.launcher.daemon.server.exec.ResetDeprecationLogger.execute(ResetDeprecationLogger.java:26)
  	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
  	at org.gradle.launcher.daemon.server.exec.RequestStopIfSingleUsedDaemon.execute(RequestStopIfSingleUsedDaemon.java:34)
  	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
  	at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:74)
  	at org.gradle.launcher.daemon.server.exec.ForwardClientInput$2.call(ForwardClientInput.java:72)
  	at org.gradle.util.Swapper.swap(Swapper.java:38)
  	at org.gradle.launcher.daemon.server.exec.ForwardClientInput.execute(ForwardClientInput.java:72)
  	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
  	at org.gradle.launcher.daemon.server.exec.LogAndCheckHealth.execute(LogAndCheckHealth.java:55)
  	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
  	at org.gradle.launcher.daemon.server.exec.LogToClient.doBuild(LogToClient.java:60)
  	at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36)
  	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
  	at org.gradle.launcher.daemon.server.exec.EstablishBuildEnvironment.doBuild(EstablishBuildEnvironment.java:72)
  	at org.gradle.launcher.daemon.server.exec.BuildCommandOnly.execute(BuildCommandOnly.java:36)
  	at org.gradle.launcher.daemon.server.api.DaemonCommandExecution.proceed(DaemonCommandExecution.java:120)
  	at org.gradle.launcher.daemon.server.exec.StartBuildOrRespondWithBusy$1.run(StartBuildOrRespondWithBusy.java:50)
  	at org.gradle.launcher.daemon.server.DaemonStateCoordinator$1.run(DaemonStateCoordinator.java:297)
  	at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63)
  	at org.gradle.internal.concurrent.StoppableExecutorImpl$1.run(StoppableExecutorImpl.java:46)
  	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  	at java.lang.Thread.run(Thread.java:745)

If I remove @MappingTarget Application application parameter - compile is OK, without @MappingTarget have same result

[lex-em]

version: 1.2.0.Beta2

[filiphr]

@lex-em thanks a lot for the report. We should not be throwing the exception that is a bug.

Note for us for the bug in the BeanMappingMethod#applyPropertyNameBasedMapping() we have a check if the sourceType is primitive and if it is we skip it. In this case the source type is not primitive it is byte[]. However, when we try to get read accessors from it we get an NPE, because it has no type element. Maybe we need to check the component type for arrays.

@lex-em in any case your convertScanCopy is not even considered as a possibility for the mapping. The idea of @MappingTarget cannot be used for what you are trying to achieve.

I would suggest you to have a look at the new @Context. In order to achieve what you are doing you will need to use that instead.

You can do something like:

public class ApplicationContext {

    private Application application;

    @BeforeMapping
    public void beforeMapping(@MappingTarget Application application) {
        this.application = application;
    }

    public Application getApplication() {
        return application;
    }
}

And your mapper will look like:

@Mapper(uses = {AddressMapper.class}, componentModel = "spring")
public abstract class ApplicationMapper {

    public Application applicationFromDto(ApplicationDto applicationDto) {
        return applicationfromDto(applicationDto, new ApplicationContext());
    }

    @Mappings({
            ...
    })
    public abstract Application applicationFromDto(ApplicationDto applicationDto, @Context ApplicationContext context);

    public Set<SomeType> convertScanCopy(byte[][] datas, @Context ApplicationContext context) {
        return Arrays.stream(datas).map(data -> {
            SomeType obj= new SomeType();
            obj.setData(data);
            obj.setApplication(context.getApplicationContext());
            return obj;
        }).collect(Collectors.toSet());
    }
}

and you should invoke it like:

mapper.applicationFromDto(dto);
// or whatever you prefer :)
mapper.applicationFromDto(dto, new ApplicationContext());

[lex-em]

@filiphr thank you, it is wery usefull suggestion!

[filiphr]

@lex-em no problem, I am glad that it works :).

Regarding this issue, do you think that it is OK to change the title to something else that reflects the NPE? We can write the question and the answer to it in the google group, or something like that.

[lex-em]

@filiphr I think that it is OK

[filiphr]

I analyzed this better. The error comes when we try to create an automatic sub mapping method between an array and some type. This issue will be resolved if we do #1188.

[filiphr]

I think that the problem has been resolved with #1154. MapStruct will not try to create a mapping for such primitive types and will report a nice error messaging displaying what could not have been mapped. Therefore I am going to close this.