Hello,
OpenJPA advertises itself as an expandable framework and provides @Strategy
(and undocumented) @ElementStrategy annotations to create custom java<->SQL
mappings.
I would like to create support for already existing JDBC4 standard mapping
of primitive arrays in i.e. Postgres:
java double[] <-> SQL float8[]
Unfortunately it is not possible using @Strategy as enhancer blindly checks
if the field is a collection/array and refuses to do anything with it.
In the case like this a field should not be delegated to an external table
but simply embedded - same way LOBs are, with different
toDataStoreValue/toObjectValue pair as provided in the strategy
implementation below..
If we use @ElementStrategy however, i.e.:
<class>
@PersistentCollection
@ElementStrategy("gaia.cu7.dal.PostgresJPAArrayHandler")
@ElementColumns({
@ElementColumn(name="TDOUBLE")
})
private double tdouble[];
</class>
then enhancer accepts it. Schema synchronisation creates wrong DDL
suppressing given SQL type and mapping it to SQL keyword ARRAY in the
external table.
Does this rather simple requirement is not covered by openJPA?
Would be grateful for any hints, comments...
Best Regards,
Krzysztof
public class PostgresJPAArrayHandler
extends AbstractValueHandler {
public PostgresJPAArrayHandler()
{
}
/**
* Serialization ID
*/
private static final long serialVersionUID = 1L;
private static final PostgresJPAArrayHandler _instance =
new PostgresJPAArrayHandler();
/**
* Singleton instance.
*/
public static PostgresJPAArrayHandler getInstance() {
return _instance;
}
public Column[] map(ValueMapping vm, String name, ColumnIO io,
boolean adapt) {
Column col = new Column();
col.setName(name);
col.setType(JavaSQLTypes.SQL_ARRAY);
col.setTypeName("float8[]"); //////<<<--------------------- this
gets reset in mergeField or whereabouts
return new Column[]{ col };
}
public Object toDataStoreValue(ValueMapping vm, Object val,
JDBCStore store) {
//this has to be array of some integer or double for now
if (val instanceof double[]) {
try {
Array darr =
store.getConnection().createArrayOf("double", (Object[]) (
ArrayUtils.toObject((double[])val)));
return darr;
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return null;
}
/** Convert from DB rep into OM representation */
public Object toObjectValue(ValueMapping vm, Object val) {
if (val == null)
return null;
return ArrayUtils.toPrimitive((Double[])val);
}
}
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