CachedCount.java

/*
 * $Source$
 * $Revision$
 *
 * Copyright (C) 2000 William Chesters
 *
 * Part of Melati (http://melati.org), a framework for the rapid
 * development of clean, maintainable web applications.
 *
 * Melati is free software; Permission is granted to copy, distribute
 * and/or modify this software under the terms either:
 *
 * a) the GNU General Public License as published by the Free Software
 *    Foundation; either version 2 of the License, or (at your option)
 *    any later version,
 *
 *    or
 *
 * b) any version of the Melati Software License, as published
 *    at http://melati.org
 *
 * You should have received a copy of the GNU General Public License and
 * the Melati Software License along with this program;
 * if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the
 * GNU General Public License and visit http://melati.org to obtain the
 * Melati Software License.
 *
 * Feel free to contact the Developers of Melati (http://melati.org),
 * if you would like to work out a different arrangement than the options
 * outlined here.  It is our intention to allow Melati to be used by as
 * wide an audience as possible.
 *
 * 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 General Public License for more details.
 *
 * Contact details for copyright holder:
 *
 *     William Chesters <williamc At paneris.org>
 *     http://paneris.org/~williamc
 *     Obrechtstraat 114, 2517VX Den Haag, The Netherlands
 */

package org.melati.poem;

/**
 * A cached instance of an SQL <code>count</code> query.
 */
public class CachedCount extends CachedQuery <Integer> {

  /**
   * Constructor.
   * @param table the table of which we are a count
   * @param whereClause discriminator, may be null
   * @param otherTables other tables involved in whereClause, if any
   */
  public CachedCount(final Table<?> table,
                       final String whereClause,
                       final Table<?> otherTables[]) {
    super(table, table.countSQL(whereClause), otherTables);
  }

  /**
   * Create a count from a Persistent.
   *
   * @param criteria the Persistent representing the query
   * @param includeDeleted whether to include records marked as deleted
   * @param excludeUnselectable Whether to append unselectable exclusion SQL 
   */
  public CachedCount(final Persistent criteria,
                     boolean includeDeleted, boolean excludeUnselectable) {
    super(criteria.getTable(),
          ((JdbcPersistent)criteria).countMatchSQL(includeDeleted, excludeUnselectable),
          null);
  }

  /**
   * Constructor where whereClause does not involve other tables.
   * @param table the table to count
   * @param whereClause discrimination, can be null
   */
  public CachedCount(final Table<?> table, final String whereClause) {
    this(table, whereClause, null);
  }

  /**
   * @return the count itself
   */
  public int count() {
    compute();
    return ((Integer)this.rows.elementAt(0)).intValue();
  }

}