pxf/pxf-jdbc/src/main/java/org/apache/hawq/pxf/plugins/jdbc/JdbcReadResolver.java

package org.apache.hawq.pxf.plugins.jdbc;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hawq.pxf.api.*;
import org.apache.hawq.pxf.api.io.DataType;
import org.apache.hawq.pxf.api.utilities.ColumnDescriptor;
import org.apache.hawq.pxf.api.utilities.InputData;
import org.apache.hawq.pxf.api.utilities.Plugin;

import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

/**
 * Class JdbcReadResolver Read the Jdbc ResultSet, and generates the data type - List {@link OneField}.
 */
public class JdbcReadResolver extends Plugin implements ReadResolver {
    private static final Log LOG = LogFactory.getLog(JdbcReadResolver.class);
    //HAWQ Table column definitions
    private ArrayList<ColumnDescriptor> columns = null;

    public JdbcReadResolver(InputData input) {
        super(input);
        columns = input.getTupleDescription();
    }

    @Override
    public List<OneField> getFields(OneRow row) throws Exception {
        ResultSet result = (ResultSet) row.getData();
        LinkedList<OneField> fields = new LinkedList<>();

        for (int i = 0; i < columns.size(); i++) {
            ColumnDescriptor column = columns.get(i);
            String colName = column.columnName();
            Object value = null;

            OneField oneField = new OneField();
            oneField.type = column.columnTypeCode();

            switch (DataType.get(oneField.type)) {
                case INTEGER:
                    value = result.getInt(colName);
                    break;
                case FLOAT8:
                    value = result.getDouble(colName);
                    break;
                case REAL:
                    value = result.getFloat(colName);
                    break;
                case BIGINT:
                    value = result.getLong(colName);
                    break;
                case SMALLINT:
                    value = result.getShort(colName);
                    break;
                case BOOLEAN:
                    value = result.getBoolean(colName);
                    break;
                case BYTEA:
                    value = result.getBytes(colName);
                    break;
                case VARCHAR:
                case BPCHAR:
                case TEXT:
                case NUMERIC:
                    value = result.getString(colName);
                    break;
                case TIMESTAMP:
                case DATE:
                    value = result.getDate(colName);
                    break;
                default:
                    throw new UnsupportedOperationException("Unknwon Field Type : " + DataType.get(oneField.type).toString()
                            + ", Column : " + column.toString());
            }
            oneField.val = value;
            fields.add(oneField);
        }
        return fields;
    }

}