Null Object Reference - DeepClone

[vsederburg]

I'm getting an error using Mapper.DeepClone to clone a class. This was working sometime in the past few weeks, so I'm not sure what has changed. I'm using the current Mapper version 1.7.2 via nuGet.

I seem to remember at one point there was a problem cloning an object that included a dictionary, but I think that was fixed.

I've attached the class and base class that I'm trying to clone. Let me know if I can provide any other information.

Thank you!

This is the error:

System.NullReferenceException: Object reference not set to an instance of an object.
at AgileObjects.AgileMapper.Members.QualifiedMember.Append(Member childMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.GetNonEnumerableChildMember(QualifiedMember parentMember, Member childMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.TargetMemberEverRepeatsWithin(QualifiedMember parentMember, IQualifiedMember subjectMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.TargetMemberEverRepeatsWithin(QualifiedMember parentMember, IQualifiedMember subjectMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.TargetMemberEverRepeatsWithin(QualifiedMember parentMember, IQualifiedMember subjectMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.TargetMemberEverRepeatsWithin(QualifiedMember parentMember, IQualifiedMember subjectMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.TargetMemberEverRepeatsWithin(QualifiedMember parentMember, IQualifiedMember subjectMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.TargetMemberEverRepeatsWithin(QualifiedMember parentMember, IQualifiedMember subjectMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.TargetMemberEverRepeatsWithin(QualifiedMember parentMember, IQualifiedMember subjectMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.TargetMemberEverRepeatsWithin(QualifiedMember parentMember, IQualifiedMember subjectMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.TargetMemberEverRepeatsWithin(QualifiedMember parentMember, IQualifiedMember subjectMember)
at AgileObjects.AgileMapper.Members.MemberMapperDataExtensions.IsRepeatMapping(IQualifiedMemberContext context)
at AgileObjects.AgileMapper.ObjectPopulation.ObjectMapperData.get_IsRepeatMapping()
at AgileObjects.AgileMapper.ObjectPopulation.ObjectMapperData.IsNotTargetTypeFirstMapping(ObjectMapperData parent)
at AgileObjects.AgileMapper.ObjectPopulation.ObjectMapperData..ctor(IMappingContext mappingContext, IQualifiedMember sourceMember, QualifiedMember targetMember, Nullable1 dataSourceIndex, ObjectMapperData declaredTypeMapperData, ObjectMapperData parent, Boolean isForStandaloneMapping) at AgileObjects.AgileMapper.ObjectPopulation.ObjectMapperData.For[TSource,TTarget](ObjectMappingData2 mappingData)
at AgileObjects.AgileMapper.ObjectPopulation.ObjectMappingData2.get_MapperData() at AgileObjects.AgileMapper.ObjectPopulation.MappingFactory.GetChildMapping(IObjectMappingData childMappingData, MappingValues mappingValues, ObjectMapperData declaredTypeMapperData) at AgileObjects.AgileMapper.ObjectPopulation.MappingFactory.GetChildMapping(IQualifiedMember sourceMember, Expression sourceMemberAccess, Int32 dataSourceIndex, IChildMemberMappingData childMappingData) at AgileObjects.AgileMapper.DataSources.EnumerableDataSource.GetMapping(IDataSource sourceEnumerableDataSource, Int32 dataSourceIndex, IChildMemberMappingData enumerableMappingData) at AgileObjects.AgileMapper.DataSources.Factories.DataSourceFindContext.GetFinalDataSource(IDataSource foundDataSource, IChildMemberMappingData mappingData) at AgileObjects.AgileMapper.DataSources.Factories.DataSourceFindContext.GetSourceMemberDataSource() at AgileObjects.AgileMapper.DataSources.Factories.DataSourceFindContext.get_MatchingSourceMemberDataSource() at AgileObjects.AgileMapper.DataSources.Factories.DataSourceFindContext.UseSourceMemberDataSource() at AgileObjects.AgileMapper.DataSources.Factories.SourceMemberDataSourcesFactory.<Create>d__0.MoveNext() at AgileObjects.AgileMapper.DataSources.Factories.MemberDataSourceSetFactory.<EnumerateDataSources>d__2.MoveNext() at System.Linq.Buffer1..ctor(IEnumerable1 source) at System.Linq.Enumerable.ToArray[TSource](IEnumerable1 source)
at AgileObjects.AgileMapper.DataSources.Factories.MemberDataSourceSetFactory.CreateFor(DataSourceFindContext findContext)
at AgileObjects.AgileMapper.Members.Population.MemberPopulatorFactory.Create(MemberPopulationContext context)
at AgileObjects.AgileMapper.Members.Population.MemberPopulatorFactory.<>c.b__3_0(MemberPopulationContext ctx, QualifiedMember tm)
at AgileObjects.AgileMapper.Extensions.PublicEnumerableExtensions.d__13.MoveNext() at AgileObjects.AgileMapper.Extensions.PublicEnumerableExtensions.<Filter>d__42.MoveNext()
at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.PopulationExpressionFactoryBase.d__3.MoveNext()
at System.Collections.Generic.List1..ctor(IEnumerable1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable1 source) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.PopulationExpressionFactoryBase.AddPopulation(MappingCreationContext context) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeMappingExpressionFactory.AddObjectPopulation(MappingCreationContext context) at AgileObjects.AgileMapper.ObjectPopulation.MappingExpressionFactoryBase.<AddPopulationsAndCallbacks>b__11_0(MappingExpressionFactoryBase factory, MappingCreationContext ctx) at AgileObjects.AgileMapper.ObjectPopulation.MappingExpressionFactoryBase.AddPopulationsAndCallbacks[TArg](TArg argument, MappingCreationContext context, Action2 mappingBodyPopulator)
at AgileObjects.AgileMapper.ObjectPopulation.MappingExpressionFactoryBase.AddPopulationsAndCallbacks(MappingCreationContext context)
at AgileObjects.AgileMapper.ObjectPopulation.MappingExpressionFactoryBase.Create(IObjectMappingData mappingData)
at AgileObjects.AgileMapper.DataSources.ComplexTypeDataSource.Create(IObjectMappingData mappingData)
at AgileObjects.AgileMapper.DataSources.Factories.Mapping.ComplexTypeMappingDataSourceFactory.CreateFor(IObjectMappingData mappingData)
at AgileObjects.AgileMapper.DataSources.Factories.Mapping.MappingDataSourceSetFactory.CreateFor(IObjectMappingData mappingData)
at AgileObjects.AgileMapper.ObjectPopulation.ObjectMapperFactory.Create[TSource,TTarget](ObjectMappingData2 mappingData) at AgileObjects.AgileMapper.ObjectPopulation.ObjectMappingData2.GetOrCreateMapper()
at AgileObjects.AgileMapper.ObjectPopulation.MappingFactory.GetInlineMappingBlock(IObjectMappingData mappingData, MappingValues mappingValues, CreateMappingDataCallFactory createMappingDataCallFactory)
at AgileObjects.AgileMapper.ObjectPopulation.MappingFactory.GetElementMapping(IObjectMappingData elementMappingData, Expression sourceElementValue, Expression targetElementValue)
at AgileObjects.AgileMapper.ObjectPopulation.MappingFactory.GetElementMapping(Expression sourceElementValue, Expression targetElementValue, IObjectMappingData mappingData)
at AgileObjects.AgileMapper.ObjectPopulation.Enumerables.EnumerablePopulationBuilder.GetElementConversion(Expression sourceElement, IObjectMappingData enumerableMappingData)
at AgileObjects.AgileMapper.ObjectPopulation.Enumerables.Looping.IndexedSourcePopulationLoopData.GetElementMapping(IObjectMappingData enumerableMappingData)
at AgileObjects.AgileMapper.ObjectPopulation.Enumerables.EnumerablePopulationBuilder.GetElementPopulation(IPopulationLoopData loopData, IObjectMappingData enumerableMappingData)
at AgileObjects.AgileMapper.ObjectPopulation.Enumerables.Looping.PopulationLoopDataExtensions.BuildPopulationLoop[TLoopData](TLoopData loopData, EnumerablePopulationBuilder builder, IObjectMappingData mappingData, Func3 elementPopulationFactory) at AgileObjects.AgileMapper.ObjectPopulation.Enumerables.EnumerablePopulationBuilder.BuildPopulationLoop(Func3 elementPopulationFactory, IObjectMappingData mappingData)
at AgileObjects.AgileMapper.ObjectPopulation.Enumerables.EnumerablePopulationBuilder.AddNewItemsToTargetVariable(IObjectMappingData enumerableMappingData)
at AgileObjects.AgileMapper.ObjectPopulation.Enumerables.CopySourceEnumerablePopulationStrategy.Create(EnumerablePopulationBuilder builder, IObjectMappingData enumerableMappingData)
at AgileObjects.AgileMapper.ObjectPopulation.Enumerables.EnumerableMappingExpressionFactory.AddObjectPopulation(MappingCreationContext context)
at AgileObjects.AgileMapper.ObjectPopulation.MappingExpressionFactoryBase.b__11_0(MappingExpressionFactoryBase factory, MappingCreationContext ctx)
at AgileObjects.AgileMapper.ObjectPopulation.MappingExpressionFactoryBase.AddPopulationsAndCallbacks[TArg](TArg argument, MappingCreationContext context, Action2 mappingBodyPopulator) at AgileObjects.AgileMapper.ObjectPopulation.MappingExpressionFactoryBase.AddPopulationsAndCallbacks(MappingCreationContext context) at AgileObjects.AgileMapper.ObjectPopulation.MappingExpressionFactoryBase.Create(IObjectMappingData mappingData) at AgileObjects.AgileMapper.DataSources.Factories.Mapping.MappingDataSourceFactoryBase.CreateFor(IObjectMappingData mappingData) at AgileObjects.AgileMapper.DataSources.Factories.Mapping.MappingDataSourceSetFactory.CreateFor(IObjectMappingData mappingData) at AgileObjects.AgileMapper.ObjectPopulation.ObjectMapperFactory.Create[TSource,TTarget](ObjectMappingData2 mappingData)
at AgileObjects.AgileMapper.ObjectPopulation.ObjectMappingData2.GetOrCreateMapper() at AgileObjects.AgileMapper.ObjectPopulation.MappingFactory.GetInlineMappingBlock(IObjectMappingData mappingData, MappingValues mappingValues, CreateMappingDataCallFactory createMappingDataCallFactory) at AgileObjects.AgileMapper.ObjectPopulation.MappingFactory.GetChildMapping(IObjectMappingData childMappingData, MappingValues mappingValues, ObjectMapperData declaredTypeMapperData) at AgileObjects.AgileMapper.ObjectPopulation.MappingFactory.GetChildMapping(IQualifiedMember sourceMember, Expression sourceMemberAccess, Int32 dataSourceIndex, IChildMemberMappingData childMappingData) at AgileObjects.AgileMapper.DataSources.EnumerableDataSource.GetMapping(IDataSource sourceEnumerableDataSource, Int32 dataSourceIndex, IChildMemberMappingData enumerableMappingData) at AgileObjects.AgileMapper.DataSources.Factories.DataSourceFindContext.GetFinalDataSource(IDataSource foundDataSource, IChildMemberMappingData mappingData) at AgileObjects.AgileMapper.DataSources.Factories.DataSourceFindContext.GetSourceMemberDataSource() at AgileObjects.AgileMapper.DataSources.Factories.DataSourceFindContext.get_MatchingSourceMemberDataSource() at AgileObjects.AgileMapper.DataSources.Factories.DataSourceFindContext.UseSourceMemberDataSource() at AgileObjects.AgileMapper.DataSources.Factories.SourceMemberDataSourcesFactory.<Create>d__0.MoveNext() at AgileObjects.AgileMapper.DataSources.Factories.MemberDataSourceSetFactory.<EnumerateDataSources>d__2.MoveNext() at System.Linq.Buffer1..ctor(IEnumerable1 source) at System.Linq.Enumerable.ToArray[TSource](IEnumerable1 source)
at AgileObjects.AgileMapper.DataSources.Factories.MemberDataSourceSetFactory.CreateFor(DataSourceFindContext findContext)
at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeConstructionFactory.ConstructionDataInfo1..ctor(TInvokable invokable, ConstructionKey key, Int32 priority) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeConstructionFactory.ObjectNewingInfo..ctor(ConstructorInfo ctor, ConstructionKey key) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeConstructionFactory.<>c__DisplayClass9_0.<GetGreediestAvailableNewingInfos>b__0(ConstructorInfo ctor) at AgileObjects.AgileMapper.Extensions.PublicEnumerableExtensions.<>c__02.b__0_0(Func2 p, TItem item) at AgileObjects.AgileMapper.Extensions.PublicEnumerableExtensions.<Project>d__13.MoveNext()
at AgileObjects.AgileMapper.Extensions.PublicEnumerableExtensions.d__42.MoveNext() at AgileObjects.AgileMapper.Extensions.Internal.EnumerableExtensions.<TakeUntil>d__61.MoveNext()
at System.Linq.Buffer1..ctor(IEnumerable1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable1 source) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeConstructionFactory.CreateConstructionInfo[T](IEnumerable1 invokables, Func2 dataFactory) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeConstructionFactory.GetGreediestAvailableNewingInfos(IEnumerable1 constructors, ConstructionKey key, IBasicConstructionInfo greediestUnconditionalFactoryInfo)
at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeConstructionFactory.AddAutoConstructionInfos(IList1 constructionInfos, ConstructionKey key) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeConstructionFactory.<>c.<GetTargetObjectCreationInfos>b__4_0(ConstructionKey key) at AgileObjects.AgileMapper.Caching.ArrayCache2.GetOrAdd(TKey key, Func2 valueFactory) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeConstructionFactory.GetTargetObjectCreationInfos(IObjectMappingData mappingData, ConstructionKey& constructionKey) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeConstructionFactory.GetTargetObjectCreationInfos(IObjectMappingData mappingData) at AgileObjects.AgileMapper.MappingDataExtensions.GetTargetObjectCreationInfos(IObjectMappingData mappingData) at AgileObjects.AgileMapper.ObjectPopulation.ComplexTypes.ComplexTypeMappingExpressionFactory.TargetCannotBeMapped(IObjectMappingData mappingData, String& reason) at AgileObjects.AgileMapper.ObjectPopulation.MappingExpressionFactoryBase.Create(IObjectMappingData mappingData) at AgileObjects.AgileMapper.DataSources.ComplexTypeDataSource.Create(IObjectMappingData mappingData) at AgileObjects.AgileMapper.DataSources.Factories.Mapping.ComplexTypeMappingDataSourceFactory.CreateFor(IObjectMappingData mappingData) at AgileObjects.AgileMapper.DataSources.Factories.Mapping.MappingDataSourceSetFactory.CreateFor(IObjectMappingData mappingData) at AgileObjects.AgileMapper.ObjectPopulation.ObjectMapperFactory.Create[TSource,TTarget](ObjectMappingData2 mappingData)
at AgileObjects.AgileMapper.ObjectPopulation.ObjectMappingData2.GetOrCreateMapper() at AgileObjects.AgileMapper.ObjectPopulation.ObjectMapperFactory.<>c__62.b__6_0(IRootMapperKey key)
at AgileObjects.AgileMapper.Caching.ArrayCache2.GetOrAdd(TKey key, Func2 valueFactory)
at AgileObjects.AgileMapper.ObjectPopulation.ObjectMapperFactory.GetOrCreateRoot[TSource,TTarget](ObjectMappingData2 mappingData) at AgileObjects.AgileMapper.ObjectPopulation.ObjectMappingData2..ctor(TSource source, TTarget target, Nullable1 elementIndex, Object elementKey, MappingTypes mappingTypes, IMappingContext mappingContext, IObjectMappingData declaredTypeMappingData, IObjectMappingData parent, Boolean createMapper) at AgileObjects.AgileMapper.ObjectPopulation.ObjectMappingDataFactory.ForRootFixedTypes[TSource,TTarget](TSource source, TTarget target, MappingTypes mappingTypes, IMappingContext mappingContext, Boolean createMapper) at AgileObjects.AgileMapper.ObjectPopulation.ObjectMappingDataFactory.ForRootFixedTypes[TSource,TTarget](TSource source, TTarget target, IMappingContext mappingContext, Boolean createMapper) at AgileObjects.AgileMapper.MappingExecutor1.PerformMapping[TTarget](TTarget target)
at AgileObjects.AgileMapper.MappingExecutor1.PerformMapping[TTarget](MappingRuleSet ruleSet, TTarget target) at AgileObjects.AgileMapper.MappingExecutor1.ToANewTResult
at AgileObjects.AgileMapper.Mapper.AgileObjects.AgileMapper.IMapper.DeepClone[TSource](TSource source)
at AgileObjects.AgileMapper.Mapper.DeepClone[TSource](TSource source)
at mt.Client.Common.ViewModels.Activity.AttendanceGridSettingsViewModel.OnInitialize(Object[] args) in C:\Data\mt_src\csharp\mt\mt.Client.Common\ViewModels\Activity\AttendanceGridSettingsViewModel.cs:line 98
at mt.Shared.Base.MtViewModelBase.Initialize(IMtViewModelParent parent, Object[] args) in C:\Data\mt_src\csharp\mt\mt.Shared\Base\MtViewModelBase.cs:line 93
at mt.Shared.Base.MtViewModelBase.Initialize(IMtViewModelParent parent) in C:\Data\mt_src\csharp\mt\mt.Shared\Base\MtViewModelBase.cs:line 76
at mt.Client.Common.UserControls.Activity.AttendanceGridSettingsUserControl.InitializeStart(Object[] args) in C:\Data\mt_src\csharp\mt\mt.Client.Common\UserControls\Activity\AttendanceGridSettingsUserControl.cs:line 49
at mt.Shared.Base.MtUserControlBase.Initialize(Object[] args) in C:\Data\mt_src\csharp\mt\mt.Shared\Base\MtUserControlBase.cs:line 148
2021-03-09 08:02:36,278 [1] INFO - Notification: Object reference not set to an instance of an object.

ViewDataDto.cs.txt

ViewDataGridPreferencesDto.cs.txt

[vsederburg]

Oh, and I'm calling the clone simply with:

private readonly ViewDataGridPreferencesDto _viewData; // set in constructor
private ViewDataGridPreferencesDto _originalViewData;

protected some method
{
    _originalViewData = Mapper.DeepClone(_viewData);
}

[SteveWilkes]

Hello!

Thanks for letting me know about this - could I have the source for Preference, UserPreferenceDto and any other concrete types in the object tree?

Cheers,

Steve

[vsederburg]

I replied to the email and attached the files. Do they get to you that way? If I have to put them here I can do that.

[SteveWilkes]

Unfortunately not! You could attach them here or make a Git repo with them in?

[vsederburg]

Files attached!

files.zip

[SteveWilkes]

Thanks very much - I'll check this out as soon as I can 👍🏻

[replaysMike]

I'm not sure if it's related, but we are seeing null ref's internally occurring in Map<TDest>(TSource) when mapping ICollections and not sure if it's related to the above or not yet as I can't yet repro it in a unit test, but it happens in our pipeline.

EDIT: some context in my case

System.NullReferenceException: Object reference not set to an instance of an object.
   at object AgileObjects.AgileMapper.ObjectPopulation.ObjectMappingData<TSource, TTarget>.AgileObjects.AgileMapper.ObjectPopulation.IObjectMappingData.MapStart()
   at TTarget AgileObjects.AgileMapper.MappingExecutor<TSource>.PerformMapping<TTarget>(TTarget target)
   at TResult AgileObjects.AgileMapper.MappingExecutor<TSource>.ToANew<TResult>()
   at TDestination Common.Mapping.WrappedMapper<TSource, TDestination>.Map(TSource source, MappingOptions options)

[replaysMike]

my comment above was moved to it's own issue as it's different: #212

[SteveWilkes]

Hi @vsederburg,

Just looking at this now - could you let me know where the ObservableObject type (from which your DtoBase type derives) is from? I can't find one in the framework in any of the namespaces listed in DtoBase's source...

Also - and this isn't the cause of this issue and you may have already found it, but just in case - to deep-clone a ViewDataGridPreferencesDto you'll have to tell the mapper what to use for the callerSource constructor parameter, as the corresponding property is named Source:

_originalViewData = Mapper.DeepClone(_viewData, cfg => cfg
    .Map((svd, tvd) => svd.Source)
    .ToCtor<GridPreferenceCallerSource>());

Cheers,

Steve

[vsederburg]

I've attached the ObservableObject class. Sorry I missed that one.

For the ViewDataGridPreferencesDto you mentioned... would it fix that if I just changed the corresponding property name to CallerSource, or make them match one way or the other?

ObservableObject.cs.txt

[SteveWilkes]

Hi,

Thanks for ObservableObject's source - the mapper believe it or not was falling over trying to figure out how to map to its PropertyInfo[], so I've updated target member selection to exclude most BCL non-value-type targets. The mapper isn't really intended to be used to map PropertyInfos or Streams or HttpContexts or anything like that, so I believe it will still cover the vast majority of scenarios.

If ViewDataGridPreferencesDto.Source was named CallerSource - or the constructor parameter was named source - the mapper won't need the configuration, no.

Thanks again for reporting the issue!

All the best,

Steve

[vsederburg]

That's weird, that has been the base class forever and it's never complained before. Oh well, looking forward to the update. This mapper is super useful. :-)

[SteveWilkes]

Hi,

I've now uploaded a preview v1.8 release to NuGet with this issue fixed - please could you try it out and let me know how you get on?

Thanks,

Steve

[vsederburg]

YES! All seems to be working again. Thanks so much!

[SteveWilkes]

Excellent! You're welcome, thanks for checking :)

[SteveWilkes]

This fix is in the full v1.8 release, which is now available on NuGet.

Thanks!