1 /*
2 * Tentackle - https://tentackle.org
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17 */
18
19 package org.tentackle.dbms.dsl;
20
21 import org.tentackle.sql.Backend;
22 import org.tentackle.sql.DataType;
23
24 import java.util.Objects;
25
26 /**
27 * A value bound to the prepared statement.
28 * <p>
29 * The value never becomes part of the SQL code but is applied to the statement
30 * by {@link org.tentackle.dbms.Query#applyParameters}. Since a value may span more than
31 * one column, a question mark is emitted per column, but the value is registered only once.
32 *
33 * @param <T> the java type of the value
34 * @author harald
35 */
36 public class BindValue<T> implements Expression<T> {
37
38 private final T value; // the value, never null
39 private final DataType<T> dataType; // the datatype; may be null if unknown
40
41
42 /**
43 * Creates a bind value.
44 *
45 * @param value the value, never null
46 * @param dataType the datatype, null to determine it from the value's class
47 */
48 public BindValue(T value, DataType<T> dataType) {
49 this.value = Objects.requireNonNull(value, "value must be provided, use isNull() or isNotNull() instead");
50 this.dataType = dataType;
51 }
52
53
54 /**
55 * Gets the value.
56 *
57 * @return the value, never null
58 */
59 public T getValue() {
60 return value;
61 }
62
63 @Override
64 public DataType<T> getDataType() {
65 return dataType;
66 }
67
68 @Override
69 public void render(RenderContext context, int columnIndex) {
70 if (columnIndex == 0) {
71 // the parameter is applied to as many question marks as its datatype spans columns
72 context.addParameter(value);
73 }
74 context.append(Backend.SQL_PAR);
75 }
76
77 }