Exclude Fields in JPA With XML Mappings: Quick Guide

  • 19/5/2012
  • One-minute read

When you generate entity classes from XML schemas using xjc, editing the source code breaks regeneration workflows. You can still persist the objects with JPA and mark unwanted elements as transient directly in the XML mapping file.

Workflow

  1. Generate an XML schema with Trang if you only have sample documents.
  2. Create Java bindings with xjc.
  3. Define an external JPA mapping file (META-INF/orm.xml) referencing the generated classes.

Mapping Example

<entity class="com.domain.xml_1_0.Site" access="FIELD">
    <attributes>
        <transient name="siteInternalId"/>
        <transient name="siteLinkage"/>
        <id name="siteId"/>
    </attributes>
</entity>

By declaring the fields as <transient/>, JPA ignores them without modifying the generated code.

Tips

  • Keep the mapping file under version control alongside the schema so regeneration remains deterministic.
  • Use Bean Validation annotations in the mapping file if you need to enforce constraints on generated fields.
  • Consider MapStruct or custom mappers to translate JAXB objects into domain models when business logic diverges from the XML structure.
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