1 /*
2 * $Source$
3 * $Revision$
4 *
5 * Copyright (C) 2000 William Chesters
6 *
7 * Part of Melati (http://melati.org), a framework for the rapid
8 * development of clean, maintainable web applications.
9 *
10 * Melati is free software; Permission is granted to copy, distribute
11 * and/or modify this software under the terms either:
12 *
13 * a) the GNU General Public License as published by the Free Software
14 * Foundation; either version 2 of the License, or (at your option)
15 * any later version,
16 *
17 * or
18 *
19 * b) any version of the Melati Software License, as published
20 * at http://melati.org
21 *
22 * You should have received a copy of the GNU General Public License and
23 * the Melati Software License along with this program;
24 * if not, write to the Free Software Foundation, Inc.,
25 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the
26 * GNU General Public License and visit http://melati.org to obtain the
27 * Melati Software License.
28 *
29 * Feel free to contact the Developers of Melati (http://melati.org),
30 * if you would like to work out a different arrangement than the options
31 * outlined here. It is our intention to allow Melati to be used by as
32 * wide an audience as possible.
33 *
34 * This program is distributed in the hope that it will be useful,
35 * but WITHOUT ANY WARRANTY; without even the implied warranty of
36 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
37 * GNU General Public License for more details.
38 *
39 * Contact details for copyright holder:
40 *
41 * William Chesters <williamc At paneris.org>
42 * http://paneris.org/~williamc
43 * Obrechtstraat 114, 2517VX Den Haag, The Netherlands
44 */
45
46 package org.melati.poem;
47
48 import java.util.Collections;
49 import java.util.Enumeration;
50 import java.util.List;
51
52 import org.melati.poem.util.MappedEnumeration;
53
54 /**
55 * A cached instance of an SQL <code>select</code> query.
56 */
57 public class CachedSelection<P extends Persistent> extends CachedQuery<P> {
58
59 /**
60 * Constructor.
61 * @param table the primary Table we are selecting rows from
62 * @param whereClause SQL snippet
63 * @param orderByClause SQL snippet
64 * @param otherTables an Array of Tables which are also referenced in query
65 */
66 public CachedSelection(final Table<?> table,
67 final String whereClause,
68 final String orderByClause,
69 final Table<?> otherTables[]) {
70 super(table, null, otherTables);
71
72
73 String fromClause = table.quotedName();
74 if (otherTables != null) {
75 for (int i = 0; i<otherTables.length; i++) {
76 fromClause += ", " + otherTables[i].quotedName();
77 }
78 }
79 setQuery(table.selectionSQL(fromClause, whereClause, orderByClause, false, true));
80
81 }
82
83 /**
84 * Constructor for a single Table query.
85 * @param table the primary Table we are selecting rows from
86 * @param whereClause SQL snippet
87 * @param orderByClause SQL snippet
88 */
89 public CachedSelection(final Table<P> table,
90 final String whereClause,
91 final String orderByClause) {
92 this(table,whereClause,orderByClause,null);
93 }
94
95 /**
96 * @return an Enumeration of Table Row Object Ids
97 */
98 public Enumeration<Integer> troids() {
99 compute();
100 return rows.elements();
101 }
102
103 /**
104 * @return an Enumeration of Table Row ReferencePoemType objects
105 */
106 public Enumeration<P> objects() {
107 return
108 new MappedEnumeration<P,Integer>(troids()) {
109 @SuppressWarnings("unchecked")
110 public P mapped(Integer troid) {
111 return (P)table.getObject((Integer)troid);
112 }
113 };
114 }
115 /**
116 * Convenience method.
117 *
118 * @return a List of Table Row ReferencePoemType objects
119 */
120
121 public List<P> objectList() {
122 return Collections.list(objects());
123 }
124
125 /**
126 * @return the first, often only, result
127 */
128 public Persistent firstObject() {
129 return nth(0);
130 }
131
132 /**
133 * @param n index into ResultSet
134 * @return the row corresponding to the index
135 */
136 public Persistent nth(int n) {
137 compute();
138 return rows.size() <= n ?
139 null :
140 table.getObject((Integer)rows.elementAt(n));
141 }
142
143 /**
144 * @return the number of results
145 */
146 public int count() {
147 compute();
148 return this.rows.size();
149 }
150 }