Value properties are mapped in JPA using the javax.persistence.@Basic annotation. In Naked Objects' terms, this means properties whose return type is a built-in value type: specifically primitives, String, java.util.Date (and its subclasses), java.sql.Timestamp, java.math.BigDecimal, java.math.BigInteger. It is also possible to map custom value types (that is, annotated with org.nakedobjects.applib.annotation.@Value); see Chapter 6, Supporting Custom Value Types for more details.

A property annotated with @Basic will correspond to a column in a database table. JPA will map - to an appropriate SQL type - all of the built-in value types supported by Naked Objects. The other types supported by JPA - java.util.Calendar, and arrays of primitives and wrappers, and enums - are not supported by Naked Objects as value types.

JPA does also allow a property whose type is serializable to be annotated with @Basic. However, it will be stored in the database as a blob. This is therefore not a recommended approach; better is to implement a custom value type.

Properties of type java.util.Date can be annotated using @javax.persistence.Temporal. This provides a hint as to the SQL type to use: DATE, TIME or TIMESTAMP.