How to specify fragmentRootElementNames in StaxEventItemReader for nested elements? - spring-batch

Question

Working with Spring-batch 4.1.2 to consume a complex XML and write to database.
Using StaxEventItemReader for reading XML data.
I am facing an issue for nested elements, while specifying fragmentRootElementNames.
<bean id="productFileItemReader" class="org.springframework.batch.item.xml.StaxEventItemReader" scope="step">
<property name="resource" ref="inputResource" />
<property name="fragmentRootElementNames" value="ProductFeatures,ProductFeaturesDetail,SomeOtherNon-NestedFragmentNames..." />
<property name="unmarshaller" ref="productMarshaller" />
</bean>
<bean id="productMarshaller" class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
<property name="classesToBeBound">
<list>
<value>com.xyz.jaxb.ProductFeaturesType</value>
<value>com.xyz.jaxb.ProductFeaturesDetailType</value>
...Some more types
</list>
</property>
</bean>
<bean id="productFileItemProcessor" class="org.springframework.batch.item.support.ClassifierCompositeItemProcessor"
scope="step">
<property name="classifier" ref="prodItemProcessorclassifier" />
</bean>
<bean id="prodItemProcessorclassifier" class="org.springframework.classify.BackToBackPatternClassifier">
<property name="routerDelegate">
<bean class="com.xyz.batch.CustomProdTypeClassifier" />
</property>
<property name="matcherMap">
<map>
<entry key="ProductFeatures" value-ref="prodFeaturesProcessor" />
<entry key="ProductFeaturesDetail" value-ref="prodFeaturesDetailProcessor" />
</map>
</property>
</bean>
<bean id="prodItemWriter" class="org.springframework.batch.item.support.ClassifierCompositeItemWriter"
scope="step">
<property name="classifier" ref="prodItemWriterclassifier" />
</bean>
<bean id="prodItemWriterclassifier" class="org.springframework.classify.BackToBackPatternClassifier">
<property name="routerDelegate">
<bean class="com.xyz.batch.CustomProdTypeClassifier" />
</property>
<property name="matcherMap">
<map>
<entry key="ProductFeaturesDetail" value-ref="prodHibernateItemWriter" />
<entry key="ProductParameters" value-ref="myListItemWriter" />
</map>
</property>
</bean>
<bean id="myListItemWriter" class="com.xyz.writer.ListDelegateItemWriter">
<property name="delegate" ref="prodHibernateItemWriter" />
</bean>
<bean id="prodHibernateItemWriter" class="org.springframework.batch.item.database.HibernateItemWriter">
<property name="sessionFactory" ref="mySessionFactory" />
</bean>
Here is the signature of the ItemProcessors
public class ProductFeaturesProcessor implements ItemProcessor<ProductFeaturesType, List<ProductParamEntity>>{}
public class ProductFeaturesDetailProcessor implements ItemProcessor<ProductFeaturesDetailType, ProductFeaturesDetailEntity> {}
XML structure is as follows -
<ProductFeatures>
<Version>12</Version>
<MessageEN>Welcome</MessageEN>
<MessageFR>Bienvenue</MessageFR>
<ProductFeaturesDetail>
<!-- Some elements here -->
</ProductFeaturesDetail>
<ProductFeaturesDetail>
<!-- Some elements here -->
</ProductFeaturesDetail>
<ProductFeaturesDetail>
<!-- Some elements here -->
</ProductFeaturesDetail>
<ProductFeaturesDetail>
<!-- Some elements here -->
</ProductFeaturesDetail>
</ProductFeatures>
Here, ProductFeatures has minOccurs=1, maxOccurs=1.
ProductFeaturesDetail is unbounded.
Each of Version, MessageEN, MessageFR need to be persisted as a record in Table-A which has 2 columns ParamName|ParamValue Each ProductFeaturesDetail is a record to be persisted in Table-B.
i.e. The 3 elements are each mapped to ProductParamEntity (i.e. with
ParamName=Version, ParamValue=12 ; ParamName=MessageEN,
ParamValue=Welcome etc.)
Logically, ProductFeatures is NOT mapped to a table directly but data
is stored in 2 tables as List and
List into tables PRODUCT_PARAM and
PRODUCT_FEATURES_DETAIL respectively.
Here are the Objects - JAXB and Corresponding Entities
#XmlRootElement(name = "ProductFeatures")
public class ProductFeaturesType {
#XmlElement(name = "Version")
protected String version;
#XmlElement(name = "MessageEN")
protected String messageEN;
#XmlElement(name = "MessageFR")
protected String messageFR;
#XmlElement(name = "ProductFeaturesDetail")
protected List<ProductFeaturesDetailType> prodFeaturesDetail;
}
#Entity
#Table(name="PRODUCT_PARAM")
public class ProductParamsEntity extends BaseEntity implements Serializable {
#Id
#Column(name="PARAM_NAME")
private String paramName;
#Column(name="PARAM_VALUE")
private String paramValue;
}
#Entity
#Table(name="PRODUCT_FEATURES_DETAIL")
public class ProductFeaturesDetailEntity extends BaseEntity implements Serializable {
#Id
#Column(name="PROD_CATEGORY")
private String prodCategory;
//---More attributes ---
}
Here is my Job Config :
<batch:job id="consumeProductFileJob" job-repository="jobRepository" restartable="true">
<batch:step id="validateFile" parent="validateXMLSchema">
<batch:next on="COMPLETED" to="persistData" />
<batch:next on="FAILED" to="notifyException" />
</batch:step>
<batch:step id="persistData">
<batch:tasklet transaction-manager="prodHibernateTransactionManager">
<batch:chunk reader="productFileItemReader" processor="productFileItemProcessor" writer="prodItemWriter" commit-interval="500" >
</batch:chunk>
<batch:transaction-attributes isolation="DEFAULT" propagation="REQUIRED" />
</batch:tasklet>
</batch:step>
<batch:step id="notifyException">
-- Do something---
</batch:step>
</batch:job>
Issue : If I specify both as fragmentRootElementNames, only ProductFeatures elements Version, MessageEN, MessageFR are persisted
in Table-A. ProductFeaturesDetail is being ignored.
If I specify just ProductFeaturesDetail, it works fine. But I dont get
the individual elements within ProductFeatures.
I want the data from both elements. What is the way to achieve this?
P.S. I am using HibernateItemWriter for persistence.