How to use JPA AttributeConverter with Hibernate-Mapping XML (HBM 4.3)?

Question

I am trying to convert a type in my db to another type for use in my entity. Doing some research I found out about the AttributeConverter class defined in JPA 2.1 I believe.

My classes are all generated from Avro so there will be no JPA/HBM annotations used

All classes are mapped using hbm.xml files not entity mapping All db connections reading and writing works. So hbm configs are correct simply having issues with type conversion.

Relevant Tech Stack
-
HB Version: 4.3.11.Final
JPA Version: 2.1

I have tried to simply add the converter as the type

This is the only thing I can think to try. Outside of annotations which are not possible with my implementation

class.hbm.xml

<hibernate-mapping default-lazy="false">
    <class name="ACLASS" table="CASE">
        <id name="id" type="long" column="id">
            <generator class="native"/>
        </id>
        <property name="aColumn" type = "dao.converter.DateToLongConverter" column = "A_COLUMN" />
    </class>
</hibernate-mapping>

DateToLongConverter.java [Ignore the placeholder logic!]

@Converter(autoApply=true)
public class DateToLongConverter implements AttributeConverter<Long, java.sql.Date> {
    @Override
    public java.sql.Date convertToDatabaseColumn(Long millitime) {
        System.out.println(millitime);
        return new Date(1);
    }

    @Override
    public Long convertToEntityAttribute(java.sql.Date dbData) {
        System.out.println(dbData.toString());
        return 1L;

    }
}

Results with the above code are simply the exception: Could not determine type for: dao.converter.DateToLongConverter, at table: ATABLE, for columns: [org.hibernate.mapping.Column(A_COLUMN)]

I've also tried adding META-INF/persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence
        version="2.1"
        xmlns="http://xmlns.jcp.org/xml/ns/persistence"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">

    <persistence-unit name="case-consumer-persistence">
        <class>dao.converter.DateToLongConverter</class>
        <class>aClass</class>
    </persistence-unit>
</persistence>

score -2 · Answer 1 · answered Jul 09 '19 at 19:24

I have never defined a persistent entity with .xml config, but I hope it helps:

You are defining a type dao.converter.DateToLongConverter to the "aColumn", but in fact, you should define a converter to it. The type you mentioned should be the type object you are working with in your code: In your example, your type should be a Long.

This other answer will help you define your converter on xml config. Its simply another format for type name.

This is how @Convert is defined with annotations. You should be looking for replicating this template on your hbm.

@Entity
public class Person {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    @Convert(converter = DateToLongConverter.class)
    private Long aColumn;
}

How to use JPA AttributeConverter with Hibernate-Mapping XML (HBM 4.3)?

1 Answers1