Read an ARRAY from a STRUCT returned by a stored procedure

Question

In the database are three Oracle custom types (simplified) as follows:

create or replace TYPE T_ENCLOSURE AS OBJECT(
  ENCLOSURE_ID      NUMBER(32,0),
  ENCLOSUR         


        

Answer 1

As long as a Oracle specific solution is sufficient, the key lies within the DTOs. All of them have to implement ORAData and ORADataFactory

public class TAnimal implements ORAData, ORADataFactory {
    Integer animal_id, number_of_hairs;

    public TAnimal() { }

    // [ Getter and Setter omitted here ]

    @Override
    public Datum toDatum(Connection connection) throws SQLException {
        OracleConnection oracleConnection = connection.unwrap(OracleConnection.class);
        StructDescriptor structDescriptor = StructDescriptor.createDescriptor("zoo_schema.T_ANIMAL", oracleConnection);
        Object[] attributes = {
                this.animal_id,
                this.number_of_hairs
        };
        return new STRUCT(structDescriptor, oracleConnection, attributes);
    }

    @Override
    public TAnimal create(Datum datum, int sqlTypeCode) throws SQLException {
        if (datum == null) {
            return null;
        }
        Datum[] attributes = ((STRUCT) datum).getOracleAttributes();
        TAnimal result = new TAnimal();
        result.animal_id = asInteger(attributes[0]); // see TEnclosure#asInteger(Datum)
        result.number_of_hairs = asInteger(attributes[1]); // see TEnclosure#asInteger(Datum)
        return result;
    }

}

and

public class TEnclosure implements ORAData, ORADataFactory {

    Integer enclosureId;
    String enclosureName;
    List animals;

    public TEnclosure() {
        this.animals = new ArrayList<>();
    }

    // [ Getter and Setter omitted here ]

    @Override
    public Datum toDatum(Connection connection) throws SQLException {
        OracleConnection oracleConnection = connection.unwrap(OracleConnection.class);
        StructDescriptor structDescriptor = StructDescriptor.createDescriptor("zoo_schema.T_ENCLOSURE", oracleConnection);
        Object[] attributes = {
                this.enclosureId,
                this.enclosureName,
                null // TODO: solve this; however, retrieving data works without this
        };
        return new STRUCT(structDescriptor, oracleConnection, attributes);
    }

    @Override
    public TEnclosure create(Datum datum, int sqlTypeCode) throws SQLException {
        if (datum == null) {
            return null;
        }
        Datum[] attributes = ((STRUCT) datum).getOracleAttributes();
        TEnclosure result = new TEnclosure();
        result.enclosureId = asInteger(attributes[0]);
        result.enclosureName = asString(attributes[1]);
        result.animals = asListOfAnimals(attributes[2]);
        return result;
    }

    // Utility methods

    Integer asInteger(Datum datum) throws SQLException {
        if (datum == null)
            return null;
        else
            return ((NUMBER) datum).intValue(); // oracle.sql.NUMBER
    }

    String asString(Datum datum) throws SQLException {
        if (datum = null)
            return null;
        else
            return ((CHAR) datum).getString(); // oracle.sql.CHAR
    }

    List asListOfAnimals(Datum datum) throws SQLException {
        if (datum == null)
            return null;
        else {
            TAnimal factory = new TAnimal();

            List result = new ArrayList<>();

            ARRAY array = (ARRAY) datum; // oracle.sql.ARRAY
            Datum[] elements = array.getOracleArray();
            for (int i = 0; i < elements.length; i++) {
                result.add(factory.create(elements[i], 0));
            }
            return result;
        }
    }
}

then fetching the data works like so:

    TEnclosure factory = new TEnclosure();

    Connection connection = null;
    OracleConnection oracleConnection = null;
    OracleCallableStatement oracleCallableStatement = null;

    try {
        connection = MyConnectionFactory.getConnection(SOME_CONNECTION_CONFIG);
        oracleConnection = connection.unwrap(OracleConnection.class);
        oracleCallableStatement = (OracleCallableStatement) oracleConnection.prepareCall("{? = call zoo_schema.zoo_utils.GET_ENCLOSURE( ? )}");

        oracleCallableStatement.registerOutParameter(1, OracleTypes.STRUCT, "zoo_schema.T_ENCLOSURE");
        oracleCallableStatement.setInt(2, 6);  // fetch data for ENCLOSURE#6

        // Execute query
        oracleCallableStatement.executeQuery();

        // Check result
        Object oraData = oracleCallableStatement.getORAData(1, factory);
        LOGGER.info("oraData is a {}", oraData.getClass().getName()); // acme.zoo.TEnclosure

    } finally {
        ResourceUtils.closeQuietly(oracleCallableStatement);
        ResourceUtils.closeQuietly(oracleConnection);
        ResourceUtils.closeQuietly(connection); // probably not necessary...
    }