Hibernate example source code file (ForeignKey.java)

This example Hibernate source code file (ForeignKey.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Hibernate tags/keywords

fk, foreignkey, foreignkey, iterable, mappingexception, more, on_delete, override, referentialaction, referentialaction, string, string, tablespecification, tablespecification, util

The Hibernate ForeignKey.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2010 by Red Hat Inc and/or its affiliates or by
 * third-party contributors as indicated by either @author tags or express
 * copyright attribution statements applied by the authors.  All
 * third-party contributions are distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.metamodel.relational;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.hibernate.AssertionFailure;
import org.hibernate.MappingException;
import org.hibernate.dialect.Dialect;

import org.jboss.logging.Logger;

/**
 * Models the notion of a foreign key.
 * <p/>
 * Note that this need not mean a physical foreign key; we just mean a relationship between 2 table
 * specifications.
 *
 * @author Gavin King
 * @author Steve Ebersole
 */
public class ForeignKey extends AbstractConstraint implements Constraint, Exportable {
    private static final Logger LOG = Logger.getLogger( ForeignKey.class );

	private static final String ON_DELETE = " on delete ";
	private static final String ON_UPDATE = " on update ";

	private final TableSpecification targetTable;
	private List<Column> targetColumns;

	private ReferentialAction deleteRule = ReferentialAction.NO_ACTION;
	private ReferentialAction updateRule = ReferentialAction.NO_ACTION;

	protected ForeignKey(TableSpecification sourceTable, TableSpecification targetTable, String name) {
		super( sourceTable, name );
		this.targetTable = targetTable;
	}

	protected ForeignKey(TableSpecification sourceTable, TableSpecification targetTable) {
		this( sourceTable, targetTable, null );
	}

	public TableSpecification getSourceTable() {
		return getTable();
	}

	public TableSpecification getTargetTable() {
		return targetTable;
	}

	public Iterable<Column> getSourceColumns() {
		return getColumns();
	}

	public Iterable<Column> getTargetColumns() {
		return targetColumns == null
				? getTargetTable().getPrimaryKey().getColumns()
				: targetColumns;
	}

	@Override
	public void addColumn(Column column) {
		addColumnMapping( column, null );
	}

	public void addColumnMapping(Column sourceColumn, Column targetColumn) {
		if ( targetColumn == null ) {
			if ( targetColumns != null ) {
				LOG.debugf(
						"Attempt to map column [%s] to no target column after explicit target column(s) named for FK [name=%s]",
						sourceColumn.toLoggableString(),
						getName()
				);
			}
		}
		else {
			checkTargetTable( targetColumn );
			if ( targetColumns == null ) {
				if (!internalColumnAccess().isEmpty()) {
					LOG.debugf(
							"Value mapping mismatch as part of FK [table=%s, name=%s] while adding source column [%s]",
							getTable().toLoggableString(),
							getName(),
							sourceColumn.toLoggableString()
					);
				}
				targetColumns = new ArrayList<Column>();
			}
			targetColumns.add( targetColumn );
		}
		internalAddColumn( sourceColumn );
	}

	private void checkTargetTable(Column targetColumn) {
		if ( targetColumn.getTable() != getTargetTable() ) {
			throw new AssertionFailure(
					String.format(
							"Unable to add column to constraint; tables [%s, %s] did not match",
							targetColumn.getTable().toLoggableString(),
							getTargetTable().toLoggableString()
					)
			);
		}
	}

	@Override
	public String getExportIdentifier() {
		return getSourceTable().getLoggableValueQualifier() + ".FK-" + getName();
	}

	public ReferentialAction getDeleteRule() {
		return deleteRule;
	}

	public void setDeleteRule(ReferentialAction deleteRule) {
		this.deleteRule = deleteRule;
	}

	public ReferentialAction getUpdateRule() {
		return updateRule;
	}

	public void setUpdateRule(ReferentialAction updateRule) {
		this.updateRule = updateRule;
	}

	@Override
	public String[] sqlDropStrings(Dialect dialect) {
		return new String[] {
				"alter table " +
						getTable().getQualifiedName( dialect ) +
						dialect.getDropForeignKeyString() +
						getName()
		};
	}

	public String sqlConstraintStringInAlterTable(Dialect dialect) {
		String[] columnNames = new String[ getColumnSpan() ];
		String[] targetColumnNames = new String[ getColumnSpan() ];
		int i=0;
		Iterator<Column> itTargetColumn = getTargetColumns().iterator();
		for ( Column column : getColumns() ) {
			if ( ! itTargetColumn.hasNext() ) {
				throw new MappingException( "More constraint columns that foreign key target columns." );
			}
			columnNames[i] = column.getColumnName().encloseInQuotesIfQuoted( dialect );
			targetColumnNames[i] = ( itTargetColumn.next() ).getColumnName().encloseInQuotesIfQuoted( dialect );
			i++;
		}
		if ( itTargetColumn.hasNext() ) {
			throw new MappingException( "More foreign key target columns than constraint columns." );
		}
		StringBuilder sb =
				new StringBuilder(
						dialect.getAddForeignKeyConstraintString(
								getName(),
								columnNames,
								targetTable.getQualifiedName( dialect ),
								targetColumnNames,
								this.targetColumns == null
						)
				);
		// TODO: If a dialect does not support cascade-delete, can it support other actions? (HHH-6428)
		// For now, assume not.
		if ( dialect.supportsCascadeDelete() ) {
			if ( deleteRule != ReferentialAction.NO_ACTION ) {
				sb.append( ON_DELETE ).append( deleteRule.getActionString() );
			}
			if ( updateRule != ReferentialAction.NO_ACTION ) {
				sb.append( ON_UPDATE ).append( updateRule.getActionString() );
			}
		}
		return sb.toString();
	}

	public static enum ReferentialAction {
		NO_ACTION( "no action" ),
		CASCADE( "cascade" ),
		SET_NULL( "set null" ),
		SET_DEFAULT( "set default" ),
		RESTRICT( "restrict" );

		private final String actionString;

		private ReferentialAction(String actionString) {
			this.actionString = actionString;
		}

		public String getActionString() {
			return actionString;
		}
	}
}