JDBCExternalForeignKey.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.mappingsmodel.spi.db.jdbc;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.eclipse.persistence.tools.workbench.mappingsmodel.spi.db.ExternalForeignKey;
import org.eclipse.persistence.tools.workbench.mappingsmodel.spi.db.ExternalForeignKeyColumnPair;
import org.eclipse.persistence.tools.workbench.mappingsmodel.spi.db.ExternalTableDescription;
import org.eclipse.persistence.tools.workbench.utility.string.StringTools;


/**
 *
 */
final class JDBCExternalForeignKey implements ExternalForeignKey {
    private final JDBCExternalTable table;
    private final String name;
    private final ExternalTableDescription targetTableDescription;
    private ExternalForeignKeyColumnPair[] columnPairs;        // pseudo-final


    // ********** constructor/initialization **********

    /**
     * Construct a "skeleton" external foreign key with the data from the current
     * row of the specified result set. The column pairs will be added later.
     * @see java.sql.DatabaseMetaData#getImportedKeys(String, String, String)
     */
    JDBCExternalForeignKey(JDBCExternalTable table, String name, ResultSet resultSet) {
        super();
        this.table = table;
        this.name = name;
        this.targetTableDescription = new JDBCExternalTableDescription(
                this.stringFrom(resultSet, 1),        // PKTABLE_CAT
                this.stringFrom(resultSet, 2),        // PKTABLE_SCHEM
                this.stringFrom(resultSet, 3),        // PKTABLE_NAME
                this.database()
            );
        // the column pairs will be added by the table, momentarily
    }

    private String stringFrom(ResultSet resultSet, int colIndex) {
        try {
            return this.trim(resultSet.getString(colIndex));
        } catch (SQLException ex) {
            // defensive - return null if the requested column is not supported by the driver
            return null;
        }
    }

    /**
     * trim down the specified string, to null if necessary
     */
    private String trim(String s) {
        if (s == null) {
            return null;
        }
        s = s.trim();
        return (s.length() == 0) ? null : s;
    }


    // ********** ExternalForeignKey implementation **********

    /**
     * @see org.eclipse.persistence.tools.workbench.mappingsmodel.spi.db.ExternalForeignKey#getName()
     */
    public String getName() {
        return this.name;
    }

    /**
     * @see org.eclipse.persistence.tools.workbench.mappingsmodel.spi.db.ExternalForeignKey#getColumnPairs()
     */
    public ExternalForeignKeyColumnPair[] getColumnPairs() {
        return this.columnPairs;
    }

    /**
     * @see org.eclipse.persistence.tools.workbench.mappingsmodel.spi.db.ExternalForeignKey#getTargetTableDescription()
     */
    public ExternalTableDescription getTargetTableDescription() {
        return this.targetTableDescription;
    }


    // ********** behavior **********

    void addColumnPair(ResultSet resultSet) {
        int len = (this.columnPairs == null) ? 0 : this.columnPairs.length;
        JDBCExternalForeignKeyColumnPair[] temp = new JDBCExternalForeignKeyColumnPair[len + 1];
        if (len != 0) {
            System.arraycopy(this.columnPairs, 0, temp, 0, len);
        }
        temp[len] = new JDBCExternalForeignKeyColumnPair(this, resultSet);
        this.columnPairs = temp;
    }


    // ********** queries **********

    JDBCExternalColumn columnNamed(String columnName) {
        return this.table.columnNamed(columnName);
    }

    private JDBCExternalDatabase database() {
        return this.table.database();
    }

    /**
     * @see Object#toString()
     */
    public String toString() {
        return StringTools.buildToStringFor(this, this.name);
    }

}