|
1 /**************************************************************************** |
|
2 ** |
|
3 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). |
|
4 ** All rights reserved. |
|
5 ** Contact: Nokia Corporation (qt-info@nokia.com) |
|
6 ** |
|
7 ** This file is part of the documentation of the Qt Toolkit. |
|
8 ** |
|
9 ** $QT_BEGIN_LICENSE:LGPL$ |
|
10 ** No Commercial Usage |
|
11 ** This file contains pre-release code and may not be distributed. |
|
12 ** You may use this file in accordance with the terms and conditions |
|
13 ** contained in the Technology Preview License Agreement accompanying |
|
14 ** this package. |
|
15 ** |
|
16 ** GNU Lesser General Public License Usage |
|
17 ** Alternatively, this file may be used under the terms of the GNU Lesser |
|
18 ** General Public License version 2.1 as published by the Free Software |
|
19 ** Foundation and appearing in the file LICENSE.LGPL included in the |
|
20 ** packaging of this file. Please review the following information to |
|
21 ** ensure the GNU Lesser General Public License version 2.1 requirements |
|
22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. |
|
23 ** |
|
24 ** In addition, as a special exception, Nokia gives you certain additional |
|
25 ** rights. These rights are described in the Nokia Qt LGPL Exception |
|
26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. |
|
27 ** |
|
28 ** If you have questions regarding the use of this file, please contact |
|
29 ** Nokia at qt-info@nokia.com. |
|
30 ** |
|
31 ** |
|
32 ** |
|
33 ** |
|
34 ** |
|
35 ** |
|
36 ** |
|
37 ** |
|
38 ** $QT_END_LICENSE$ |
|
39 ** |
|
40 ****************************************************************************/ |
|
41 |
|
42 /*! |
|
43 \example xmlpatterns/recipes |
|
44 \title Recipes Example |
|
45 |
|
46 The recipes example shows how to use QtXmlPatterns to query XML data |
|
47 loaded from a file. |
|
48 |
|
49 \tableofcontents |
|
50 |
|
51 \section1 Introduction |
|
52 |
|
53 In this case, the XML data represents a cookbook, \c{cookbook.xml}, |
|
54 which contains \c{<cookbook>} as its document element, which in turn |
|
55 contains a sequence of \c{<recipe>} elements. This XML data is |
|
56 searched using queries stored in XQuery files (\c{*.xq}). |
|
57 |
|
58 \section2 The User Interface |
|
59 |
|
60 The UI for this example was created using \l{Qt Designer Manual} {Qt |
|
61 Designer}: |
|
62 |
|
63 \image recipes-example.png |
|
64 |
|
65 The UI consists of three \l{QGroupBox} {group boxes} arranged |
|
66 vertically. The top one contains a \l{QTextEdit} {text viewer} that |
|
67 displays the XML text from the cookbook file. The middle group box |
|
68 contains a \l{QComboBox} {combo box} for choosing the \l{A Short |
|
69 Path to XQuery} {XQuery} to run and a \l{QTextEdit} {text viewer} |
|
70 for displaying the text of the selected XQuery. The \c{.xq} files in |
|
71 the file list above are shown in the combo box menu. Choosing an |
|
72 XQuery loads, parses, and runs the selected XQuery. The query result |
|
73 is shown in the bottom group box's \l{QTextEdit} {text viewer}. |
|
74 |
|
75 \section2 Running your own XQueries |
|
76 |
|
77 You can write your own XQuery files and run them in the example |
|
78 program. The file \c{xmlpatterns/recipes/recipes.qrc} is the \l{The |
|
79 Qt Resource System} {resource file} for this example. It is used in |
|
80 \c{main.cpp} (\c{Q_INIT_RESOURCE(recipes);}). It lists the XQuery |
|
81 files (\c{.xq}) that can be selected in the combobox. |
|
82 |
|
83 \quotefromfile examples/xmlpatterns/recipes/recipes.qrc |
|
84 \printuntil |
|
85 |
|
86 To add your own queries to the example's combobox, store your |
|
87 \c{.xq} files in the \c{examples/xmlpatterns/recipes/files} |
|
88 directory and add them to \c{recipes.qrc} as shown above. |
|
89 |
|
90 \section1 Code Walk-Through |
|
91 |
|
92 The example's main() function creates the standard instance of |
|
93 QApplication. Then it creates an instance of the UI class, shows it, |
|
94 and starts the Qt event loop: |
|
95 |
|
96 \snippet examples/xmlpatterns/recipes/main.cpp 0 |
|
97 |
|
98 \section2 The UI Class: QueryMainWindow |
|
99 |
|
100 The example's UI is a conventional Qt GUI application inheriting |
|
101 QMainWindow and the class generated by \l{Qt Designer Manual} {Qt |
|
102 Designer}: |
|
103 |
|
104 \snippet examples/xmlpatterns/recipes/querymainwindow.h 0 |
|
105 |
|
106 The constructor finds the window's \l{QComboBox} {combo box} child |
|
107 widget and connects its \l{QComboBox::currentIndexChanged()} |
|
108 {currentIndexChanged()} signal to the window's \c{displayQuery()} |
|
109 slot. It then calls \c{loadInputFile()} to load \c{cookbook.xml} and |
|
110 display its contents in the top group box's \l{QTextEdit} {text |
|
111 viewer} . Finally, it finds the XQuery files (\c{.xq}) and adds each |
|
112 one to the \l{QComboBox} {combo box} menu. |
|
113 |
|
114 \snippet examples/xmlpatterns/recipes/querymainwindow.cpp 0 |
|
115 |
|
116 The work is done in the \l{displayQuery() slot} {displayQuery()} |
|
117 slot and the \l{evaluate() function} {evaluate()} function it |
|
118 calls. \l{displayQuery() slot} {displayQuery()} loads and displays |
|
119 the selected query file and passes the XQuery text to \l{evaluate() |
|
120 function} {evaluate()}. |
|
121 |
|
122 \target displayQuery() slot |
|
123 \snippet examples/xmlpatterns/recipes/querymainwindow.cpp 1 |
|
124 |
|
125 \l{evaluate() function} {evaluate()} demonstrates the standard |
|
126 QtXmlPatterns usage pattern. First, an instance of QXmlQuery is |
|
127 created (\c{query}). The \c{query's} \l{QXmlQuery::bindVariable()} |
|
128 {bindVariable()} function is then called to bind the \c cookbook.xml |
|
129 file to the XQuery variable \c inputDocument. \e{After} the variable |
|
130 is bound, \l{QXmlQuery::setQuery()} {setQuery()} is called to pass |
|
131 the XQuery text to the \c query. |
|
132 |
|
133 \note \l{QXmlQuery::setQuery()} {setQuery()} must be called |
|
134 \e{after} \l{QXmlQuery::bindVariable()} {bindVariable()}. |
|
135 |
|
136 Passing the XQuery to \l{QXmlQuery::setQuery()} {setQuery()} causes |
|
137 QtXmlPatterns to parse the XQuery. \l{QXmlQuery::isValid()} is |
|
138 called to ensure that the XQuery was correctly parsed. |
|
139 |
|
140 \target evaluate() function |
|
141 \snippet examples/xmlpatterns/recipes/querymainwindow.cpp 2 |
|
142 |
|
143 If the XQuery is valid, an instance of QXmlFormatter is created to |
|
144 format the query result as XML into a QBuffer. To evaluate the |
|
145 XQuery, an overload of \l{QXmlQuery::evaluateTo()} {evaluateTo()} is |
|
146 called that takes a QAbstractXmlReceiver for its output |
|
147 (QXmlFormatter inherits QAbstractXmlReceiver). Finally, the |
|
148 formatted XML result is displayed in the UI's bottom text view. |
|
149 |
|
150 \note Each XQuery \c{.xq} file must declare the \c{$inputDocument} |
|
151 variable to represent the \c cookbook.xml document: |
|
152 |
|
153 \code |
|
154 (: All ingredients for Mushroom Soup. :) |
|
155 declare variable $inputDocument external; |
|
156 |
|
157 doc($inputDocument)/cookbook/recipe[@xml:id = "MushroomSoup"]/ingredient/ |
|
158 <p>{@name, @quantity}</p> |
|
159 \endcode |
|
160 |
|
161 \note If you add add your own query.xq files, you must declare the |
|
162 \c{$inputDocument} and use it as shown above. |
|
163 |
|
164 */ |