src/java/org/apache/ddlutils/alteration/ColumnDefinitionChange.java

package org.apache.ddlutils.alteration;

/*
 * 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.ddlutils.PlatformInfo;
import org.apache.ddlutils.model.Column;
import org.apache.ddlutils.model.Database;
import org.apache.ddlutils.util.StringUtils;

/**
 * Represents the change of one or more aspects of the definition of a column, such as
 * data type or size, whether it is required or not, etc. Note that primary key status
 * is not part of the definition.
 * 
 * @version $Revision: $
 */
public class ColumnDefinitionChange extends ColumnChangeImplBase
{
    /** The target column definition. */
    private Column _newColumnDef;

    /**
     * Creates a new change object.
     * 
     * @param tableName    The name of the table owning the changed column
     * @param columnName   The name of the changed column
     * @param newColumnDef The new column definition
     */
    public ColumnDefinitionChange(String tableName, String columnName, Column newColumnDef)
    {
        super(tableName, columnName);
        _newColumnDef = newColumnDef;
    }

    /**
     * Returns the new column definition.
     *
     * @return The new column
     */
    public Column getNewColumn()
    {
        return _newColumnDef;
    }

    /**
     * Determines whether the definition of the given target column is different from the one of the given source column.
     * 
     * @param platformInfo The info object for the current platform
     * @param sourceColumn The source column
     * @param targetColumn The target column
     * @return <code>true</code> if the definitions differ
     */
    public static boolean isChanged(PlatformInfo platformInfo, Column sourceColumn, Column targetColumn)
    {
        return isTypeChanged(platformInfo, sourceColumn, targetColumn) ||
               isSizeChanged(platformInfo, sourceColumn, targetColumn) ||
               isDefaultValueChanged(sourceColumn, targetColumn) ||
               isRequiredStatusChanged(sourceColumn, targetColumn) ||
               isAutoIncrementChanged(sourceColumn, targetColumn);
    }

    /**
     * Determines whether the jdbc type of the given target column is different from the one of the given source column.
     * This method uses the platform info object to determine the actual jdbc type that the target column would have
     * in the database, and compares that to the type of he source column.
     * 
     * @param platformInfo The info object for the current platform
     * @param sourceColumn The source column
     * @param targetColumn The target column
     * @return <code>true</code> if the jdbc types differ
     */
    public static boolean isTypeChanged(PlatformInfo platformInfo, Column sourceColumn, Column targetColumn)
    {
        int targetTypeCode = platformInfo.getTargetJdbcType(targetColumn.getTypeCode());

        return targetTypeCode != sourceColumn.getTypeCode();
    }

    /**
     * Determines whether the size or precision/scale of the given target column is different from that of the given source column.
     * If size and precision/scale do not matter for the target column's type, then <code>false</code> is returned.
     * 
     * @param platformInfo The info object for the current platform
     * @param sourceColumn The source column
     * @param targetColumn The target column
     * @return <code>true</code> if the sizes or precisions/scales differ
     */
    public static boolean isSizeChanged(PlatformInfo platformInfo, Column sourceColumn, Column targetColumn)
    {
        int     targetTypeCode = platformInfo.getTargetJdbcType(targetColumn.getTypeCode());
        boolean sizeMatters    = platformInfo.hasSize(targetTypeCode);
        boolean scaleMatters   = platformInfo.hasPrecisionAndScale(targetTypeCode);

        if (sizeMatters && !StringUtils.equals(sourceColumn.getSize(), targetColumn.getSize()))
        {
            return true;
        }
        else if (scaleMatters &&
                 (sourceColumn.getPrecisionRadix() != targetColumn.getPrecisionRadix()) ||
                  (sourceColumn.getScale() != targetColumn.getScale()))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    /**
     * Determines whether the default value of the given target column is different from the one of the given source column.
     * This method compares the parsed default values instead of their representations in the columns.
     * 
     * @param sourceColumn The source column
     * @param targetColumn The target column
     * @return <code>true</code> if the default values differ
     */
    public static boolean isDefaultValueChanged(Column sourceColumn, Column targetColumn)
    {
        Object sourceDefaultValue = sourceColumn.getParsedDefaultValue();
        Object targetDefaultValue = targetColumn.getParsedDefaultValue();

        return ((sourceDefaultValue == null) && (targetDefaultValue != null)) ||
               ((sourceDefaultValue != null) && !sourceDefaultValue.equals(targetDefaultValue));
    }

    /**
     * Determines whether the required status of the given target column is different from that of the given source column.
     * 
     * @param sourceColumn The source column
     * @param targetColumn The target column
     * @return <code>true</code> if the required status is different in the target column
     */
    public static boolean isRequiredStatusChanged(Column sourceColumn, Column targetColumn)
    {
        return sourceColumn.isRequired() != targetColumn.isRequired();
    }

    /**
     * Determines whether the auto increment status of the given target column is different from that of the given source column.
     * 
     * @param sourceColumn The source column
     * @param targetColumn The target column
     * @return <code>true</code> if the auto increment status is different in the target column
     */
    public static boolean isAutoIncrementChanged(Column sourceColumn, Column targetColumn)
    {
        return sourceColumn.isAutoIncrement() != targetColumn.isAutoIncrement();
    }

    /**
     * {@inheritDoc}
     */
    public void apply(Database model, boolean caseSensitive)
    {
        Column column = findChangedColumn(model, caseSensitive);

        column.setTypeCode(_newColumnDef.getTypeCode());
        column.setSize(_newColumnDef.getSize());
        column.setAutoIncrement(_newColumnDef.isAutoIncrement());
        column.setRequired(_newColumnDef.isRequired());
        column.setDescription(_newColumnDef.getDescription());
        column.setDefaultValue(_newColumnDef.getDefaultValue());
    }
}