how to handle nested @DynamoDBDocument

Question

I have a domain called UserAdvice which has a variable of type PriceWithPaf, which has 2 variables in it, which are again of custom-type/class-object. I have declared both the inner-objects/variables and the parent class which is a variable in the Domain as @DynamoDBDocument.

The best part is I am able to save the data exactly the way I want in DynamoDB Database but when I read the data back to object I get following error: (I am using spring data for dynamoDB - from github & this error is shown in test case - where I use AmazonDynamoDBLocal)

    com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingException: UserAdvise[averageEntryPrice]; could not unconvert attribute
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperTableModel.unconvert(DynamoDBMapperTableModel.java:271)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.privateMarshallIntoObject(DynamoDBMapper.java:456)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.marshallIntoObjects(DynamoDBMapper.java:484)
    at com.amazonaws.services.dynamodbv2.datamodeling.PaginatedScanList.<init>(PaginatedScanList.java:64)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.scan(DynamoDBMapper.java:1458)
    at com.amazonaws.services.dynamodbv2.datamodeling.AbstractDynamoDBMapper.scan(AbstractDynamoDBMapper.java:216)
    at org.socialsignin.spring.data.dynamodb.core.DynamoDBTemplate.scan(DynamoDBTemplate.java:112)
    at org.socialsignin.spring.data.dynamodb.repository.support.SimpleDynamoDBCrudRepository.findAll(SimpleDynamoDBCrudRepository.java:166)
    at org.socialsignin.spring.data.dynamodb.repository.support.SimpleDynamoDBCrudRepository.findAll(SimpleDynamoDBCrudRepository.java:43)
    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:497)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:503)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:488)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:460)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:61)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
    at com.sun.proxy.$Proxy68.findAll(Unknown Source)
    at com.wt.api.write.WDAuthenticationShould.return_200_for_virtual_and_real_advises_and_wallet_amount(WDAuthenticationShould.java:1079)
    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:497)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:73)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:82)
    at org.junit.rules.ExternalResource$1.evaluate(ExternalResource.java:48)
    at org.junit.contrib.java.lang.system.EnvironmentVariables$EnvironmentVariablesStatement.evaluate(EnvironmentVariables.java:71)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:73)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:224)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:83)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:68)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:163)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingException: PriceWithPaf[nonDividendPaf]; could not unconvert attribute
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperTableModel.unconvert(DynamoDBMapperTableModel.java:271)
    at com.amazonaws.services.dynamodbv2.datamodeling.StandardModelFactories$Rules$ObjectDocumentMap$1.unconvert(StandardModelFactories.java:603)
    at com.amazonaws.services.dynamodbv2.datamodeling.StandardModelFactories$Rules$ObjectDocumentMap$1.unconvert(StandardModelFactories.java:598)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTypeConverter$DelegateConverter.unconvert(DynamoDBTypeConverter.java:109)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTypeConverter$NullSafeConverter.unconvert(DynamoDBTypeConverter.java:128)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBTypeConverter$ExtendedConverter.unconvert(DynamoDBTypeConverter.java:88)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperFieldModel.unconvert(DynamoDBMapperFieldModel.java:146)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperFieldModel.unconvertAndSet(DynamoDBMapperFieldModel.java:164)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperTableModel.unconvert(DynamoDBMapperTableModel.java:267)
    ... 57 more
Caused by: com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingException: could not invoke null on class com.wt.domain.PriceWithPaf with value 1.0 of type class java.lang.Double
    at com.amazonaws.services.dynamodbv2.datamodeling.StandardBeanProperties$MethodReflect.set(StandardBeanProperties.java:136)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperFieldModel.set(DynamoDBMapperFieldModel.java:111)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperFieldModel.unconvertAndSet(DynamoDBMapperFieldModel.java:164)
    at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapperTableModel.unconvert(DynamoDBMapperTableModel.java:267)
    ... 65 more
Caused by: java.lang.NullPointerException
    at com.amazonaws.services.dynamodbv2.datamodeling.StandardBeanProperties$MethodReflect.set(StandardBeanProperties.java:133)
    ... 68 more

Answer 1

After facing this issue and trying to solve it for 3 days. Finally came across this article , it worked .

My mistake was :

Initial

@DynamoDBAttribute
public String getPeriod() {
    return period;
}

public void set_period(String period) {
    this.period = period;
}

Changed it to :

@DynamoDBAttribute
public String getPeriod() {
    return period;
}

public void setPeriod(String period) {
    this.period = period;
}

Answer 2

It worked - the error was due to wrong getter setup - one of the getter was suppose to return custom object (PriceWithPaf) instead of returning a double.

This made the unmapping of dynamoDBDocument go wrong.

using DynamoDBDocument is easy - just put this annotation on all the class which acts as a variable to the Domain Class. and make sure your getter and setter are default/not manipulated ;)