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spring-mvcmapstruct

Internal error in the mapping processor: java.lang.NullPointerException

I'm trying to my map local pojo to an autogenerated domain objects using mapstruct. Expect for a specific complex structure everything else seems to map and the mapper implementation class gets generation. Below is the error that I get.

My mapper class is:

@Mappings({
        @Mapping(source = "sourcefile", target = "sourceFILE"),
        @Mapping(source = "id", target = "ID"),
        @Mapping(source = "reg", target = "regID"),
        @Mapping(source = "itemDetailsType", target = "ItemDetailsType") //This is the structure that does not map
})
AutoGenDomainType map(LocalPojo localPojo);

@Mappings({
        @Mapping(source = "line", target = "LINE"),
        @Mapping(source = type", target = "TYPE")
})
ItemDetailsType map(ItemDetailsTypes itemDetailsType);

Error:

Internal error in the mapping processor: java.lang.NullPointerException         at org.mapstruct.ap.internal.processor.creation.MappingResolverImpl$ResolvingAttempt.hasCompatibleCopyConstructor(MappingResolverImpl.java:547)          at org.mapstruct.ap.internal.processor.creation.MappingResolverImpl$ResolvingAttempt.isPropertyMappable(MappingResolverImpl.java:522)   at org.mapstruct.ap.internal.processor.creation.MappingResolverImpl$ResolvingAttempt.getTargetAssignment(MappingResolverImpl.java:202)   at org.mapstruct.ap.internal.processor.creation.MappingResolverImpl$ResolvingAttempt.access$100(MappingResolverImpl.java:153)    at  org.mapstruct.ap.internal.processor.creation.MappingResolverImpl.getTargetAssignment(MappingResolverImpl.java:121)   at 
.....
.....
[ERROR] 
[ERROR] Found 1 error and 16 warnings.
[ERROR] -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project uwo-services: Compilation failure

The target object ItemDetailsType does have other properties that need not be mapped. The error says compilation issue, but I dont find any. Also I have tried adding have tried the unmappedTargetPolicy = ReportingPolicy.IGNORE at my mapper class level just to avoid if this is caused by the unmapped properties, but still no solution.

Solution

  • This is a known bug in MapStruct. The bug is reported in #729, it has been fixed in 1.1.0.Final. You are using 1.0.0.Final. I would highly suggest switching to the either 1.1.0.Final or 1.2.0.Beta2.

    Once you update you will see a better error message and you will know exactly what the problem in the mapping is.

    By looking at this first it looks like that target in @Mapping(source = "itemDetailsType", target = "ItemDetailsType") is wrong. Are you sure that you need a capital letter there?