Talk:EclipseLink/UserGuide/JPA/Basic JPA Development/Mapping/Basic Mappings/Default Conversions and Converters/StructConverter

-- Ben Gelernter 4/28/11

ELUG ref

I removed this reference that possibly is to ELUG. It currently xrefs a nonexistent target on this page. I suspect is used to be to a section in ELUG.

Return here to see if this information needs to be brought forward into this doc.

Note: You can also configure structure converters in a sessions.xml file (see What You May Need to Know About EclipseLink JPA Overriding Mechanisms).

-- Ben Gelernter 4/28/11

ELUG ref

I also removed these references to ELUG. Return here to see if this information needs to be brought forward into this doc.

For more information, see the following:

• Object-Relational Data Type Structure Mapping
• Object-Relational Data Type Descriptors

-- Ben Gelernter 4/28/11

More ELUG refs

I removed the ELUG links from the final section

==Using Structure Converters to Configure Mappings==

In EclipseLink, a DatabasePlatform (see Database Platforms) holds a structure converter. An org.eclipse.persistence.database.platform.converters.StructConverter affects all objects of a particular type read into the Session that has that DatabasePlatform. This prevents you from configuring the StructConverter on a mapping-by-mapping basis. To configure mappings that use the StructConverter, you call their setFieldType(java.sql.Types.STRUCT) method. You must call this method on all mappings that the StructConverter will affect – if you do not call it, errors might occur.

The JPA specification requires all @Basic mappings (see @Basic) that map to a non-primitive or a non-primitive-wrapper type have a serialized converter added to them. This enables certain STRUCT types to map to a field without serialization.

You can use the existing @Convert annotation with its value attribute set to the StructConverter name – in this case, EclipseLink will apply appropriate settings to the mapping. This setting will be required on all mappings that use a type for which a StructConverter has been defined. Failing to configure the mapping with the @Convert will cause an error.