net.lshift.hibernate.migrations.TransplantTableBuilder.java Source code

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Here is the source code for net.lshift.hibernate.migrations.TransplantTableBuilder.java

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/**
 * Copyright (C) 2010-2012 LShift Ltd.
 *
 * Licensed 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.
 */
package net.lshift.hibernate.migrations;

import net.lshift.hibernate.migrations.dialects.DialectExtension;
import org.hibernate.cfg.Configuration;
import org.hibernate.dialect.Dialect;
import org.hibernate.mapping.Column;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * This is used to transplant the contents of one table into another table
 * for example if you need to alter some columns in a way that your database
 * doesn't allow you to do.
 */
public class TransplantTableBuilder implements MigrationElement {

    private final String source;
    private final CreateTableBuilder tempTable;
    private final Map<String, String> renames;
    private final Configuration configuration;
    private final Dialect dialect;
    private final DialectExtension dialectExtension;

    private List<String> statements = new ArrayList<String>();

    public TransplantTableBuilder(Configuration config, Dialect dialect, DialectExtension dialectExtension,
            String source, CreateTableBuilder tempTable, Map<String, String> renames) {
        this.configuration = config;
        this.dialect = dialect;
        this.dialectExtension = dialectExtension;
        this.source = source;
        this.tempTable = tempTable;
        this.renames = renames;
    }

    public TransplantTableBuilder(Configuration config, Dialect dialect, DialectExtension dialectExtension,
            String source, CreateTableBuilder tempTable) {
        this(config, dialect, dialectExtension, source, tempTable, null);
    }

    @Override
    public void apply(Connection conn) throws SQLException {

        // Create the temporary table
        tempTable.apply(conn);

        // Copy the data from the old table to the temporary table
        List<String> sourceCols = new ArrayList<String>();
        List<String> destCols = new ArrayList<String>();

        for (Column column : tempTable.getColumns()) {
            String name = column.getName();
            destCols.add(name);
            if (renames != null && renames.containsKey(name)) {
                sourceCols.add(renames.get(name));
            } else {
                sourceCols.add(name);
            }
        }

        CopyTableBuilder copyTableBuilder = new CopyTableBuilder(source, tempTable.getTableName(), sourceCols,
                destCols);
        copyTableBuilder.apply(conn);

        // Delete the source table

        DropTableBuilder dropTableBuilder = new DropTableBuilder(configuration, dialect, source);
        dropTableBuilder.apply(conn);

        // Rename the destination table to the source table's original name
        AlterTableBuilder alterTableBuilder = new AlterTableBuilder(configuration, dialect, dialectExtension,
                tempTable.getTableName());
        alterTableBuilder.renameTo(source);
        alterTableBuilder.apply(conn);

    }

    @Override
    public List<String> getStatements() {
        return statements;
    }
}