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Java > Open Source Codes > org > objectstyle > cayenne > access > jdbc > BindDirective


1 /* ====================================================================
2  *
3  * The ObjectStyle Group Software License, version 1.1
4  * ObjectStyle Group - http://objectstyle.org/
5  *
6  * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7  * of the software. All rights reserved.
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10  * modification, are permitted provided that the following conditions
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24  * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
25  * Alternately, this acknowlegement may appear in the software itself,
26  * if and wherever such third-party acknowlegements normally appear.
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54  * <http://objectstyle.org/>.
55  */
56 package org.objectstyle.cayenne.access.jdbc;
57
58 import java.io.IOException JavaDoc;
59 import java.io.Writer JavaDoc;
60 import java.util.Collection JavaDoc;
61
62 import org.apache.velocity.context.InternalContextAdapter;
63 import org.apache.velocity.exception.MethodInvocationException;
64 import org.apache.velocity.exception.ParseErrorException;
65 import org.apache.velocity.exception.ResourceNotFoundException;
66 import org.apache.velocity.runtime.directive.Directive;
67 import org.apache.velocity.runtime.parser.node.Node;
68 import org.objectstyle.cayenne.dba.TypesMapping;
69 import org.objectstyle.cayenne.util.ConversionUtil;
70
71 /**
72  * A custom Velocity directive to create a PreparedStatement parameter text.
73  * There are the following possible invocation formats inside the template:
74  *
75  * <pre>
76  * #bind(value) - e.g. #bind($xyz)
77  * #bind(value jdbc_type_name) - e.g. #bind($xyz 'VARCHAR'). This is the most common and useful form.
78  * #bind(value jdbc_type_name, precision) - e.g. #bind($xyz 'VARCHAR' 2)</pre>
79  *
80  *
81  * <p>Other examples:</p>
82  *
83  * <p><strong>Binding literal parameter value:</strong></p>
84  * <p><code>"WHERE SOME_COLUMN > #bind($xyz)"</code> produces
85  * <code>"WHERE SOME_COLUMN > ?"</code>
86  * and also places the value of the "xyz" parameter in the context "bindings" collection.</p>
87  *
88  * <p><strong>Binding ID column of a DataObject value:</strong></p>
89  * <p><code>"WHERE ID_COL1 = #bind($helper.cayenneExp($xyz, 'db:ID_COL2'))
90  * AND ID_COL2 = #bind($helper.cayenneExp($xyz, 'db:ID_COL2'))"</code>
91  * produces <code>"WHERE ID_COL1 = ? AND ID_COL2 = ?"</code>
92  * and also places the values of id columns of the DataObject parameter "xyz" in the context
93  * "bindings" collection.</p>
94  *
95  * @since 1.1
96  * @author Andrei Adamchik
97  */
98 public class BindDirective extends Directive {
99
100     public String JavaDoc getName() {
101         return "bind";
102     }
103
104     public int getType() {
105         return LINE;
106     }
107
108     /**
109      * Extracts the value of the object property to render and passes
110      * control to {@link #render(InternalContextAdapter, Writer, ParameterBinding)}
111      * to do the actual rendering.
112      */
113     public boolean render(InternalContextAdapter context, Writer JavaDoc writer, Node node)
114         throws
115             IOException JavaDoc,
116             ResourceNotFoundException,
117             ParseErrorException,
118             MethodInvocationException {
119
120         Object JavaDoc value = getChild(context, node, 0);
121         Object JavaDoc type = getChild(context, node, 1);
122         Object JavaDoc precision = getChild(context, node, 2);
123
124         int jdbcType = TypesMapping.NOT_DEFINED;
125         if (type != null) {
126             jdbcType = TypesMapping.getSqlTypeByName(type.toString());
127         }
128         else if (value != null) {
129             jdbcType = TypesMapping.getSqlTypeByJava(value.getClass());
130         }
131
132         if (jdbcType == TypesMapping.NOT_DEFINED) {
133             throw new ParseErrorException(
134                 "Can't determine JDBC type of binding ("
135                     + value
136                     + ", "
137                     + type
138                     + ") at line "
139                     + node.getLine()
140                     + ", column "
141                     + node.getColumn());
142         }
143
144         ParameterBinding binding =
145             new ParameterBinding(value, jdbcType, ConversionUtil.toInt(precision, -1));
146
147         render(context, writer, binding);
148         return true;
149     }
150
151     protected void render(
152         InternalContextAdapter context,
153         Writer JavaDoc writer,
154         ParameterBinding binding)
155         throws IOException JavaDoc {
156
157         bind(context, binding);
158         writer.write('?');
159     }
160
161     protected Object JavaDoc getChild(InternalContextAdapter context, Node node, int i)
162         throws MethodInvocationException {
163         return (i >= 0 && i < node.jjtGetNumChildren())
164             ? node.jjtGetChild(i).value(context)
165             : null;
166     }
167
168     /**
169      * Adds value to the list of bindings in the context.
170      */
171     protected void bind(InternalContextAdapter context, ParameterBinding binding) {
172         Collection JavaDoc bindings =
173             (Collection JavaDoc) context.getInternalUserContext().get(
174                 SQLTemplateProcessor.BINDINGS_LIST_KEY);
175
176         if (bindings != null) {
177             bindings.add(binding);
178         }
179     }
180 }
181
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