- Qt 5.5
- Qt XML Patterns
- Recipes Example
- querymainwindow.cpp Example File
- Qt 5.5.1 Reference Documentation

# querymainwindow.cpp Example File

recipes/querymainwindow.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
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    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
    **     distribution.
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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    #include <QMessageBox>
    #include <QFileDialog>
    #include <QtXmlPatterns>

    #include "querymainwindow.h"
    #include "xmlsyntaxhighlighter.h"

    QueryMainWindow::QueryMainWindow() : ui_defaultQueries(0)
    {
        setupUi(this);

        new XmlSyntaxHighlighter(findChild<QTextEdit*>("inputTextEdit")->document());
        new XmlSyntaxHighlighter(findChild<QTextEdit*>("outputTextEdit")->document());

        ui_defaultQueries = findChild<QComboBox*>("defaultQueries");
        QMetaObject::connectSlotsByName(this);
        connect(ui_defaultQueries, SIGNAL(currentIndexChanged(int)), SLOT(displayQuery(int)));

        loadInputFile();
        const QStringList queries(QDir(":/files/", "*.xq").entryList());
        int len = queries.count();
        for(int i = 0; i < len; ++i)
            ui_defaultQueries->addItem(queries.at(i));
        if (len > 0)
            displayQuery(0);
    }

    void QueryMainWindow::displayQuery(int index)
    {
        QFile queryFile(QString(":files/") + ui_defaultQueries->itemText(index));
        queryFile.open(QIODevice::ReadOnly);
        const QString query(QString::fromLatin1(queryFile.readAll()));
        findChild<QTextEdit*>("queryTextEdit")->setPlainText(query);

        evaluate(query);
    }

    void QueryMainWindow::loadInputFile()
    {
        QFile forView;
        forView.setFileName(":/files/cookbook.xml");
        if (!forView.open(QIODevice::ReadOnly)) {
            QMessageBox::information(this,
                tr("Unable to open file"), forView.errorString());
            return;
        }

        QTextStream in(&forView);
        QString inputDocument = in.readAll();
        findChild<QTextEdit*>("inputTextEdit")->setPlainText(inputDocument);
    }

    void QueryMainWindow::evaluate(const QString &str)
    {
        QFile sourceDocument;
        sourceDocument.setFileName(":/files/cookbook.xml");
        sourceDocument.open(QIODevice::ReadOnly);

        QByteArray outArray;
        QBuffer buffer(&outArray);
        buffer.open(QIODevice::ReadWrite);

        QXmlQuery query;
        query.bindVariable("inputDocument", &sourceDocument);
        query.setQuery(str);
        if (!query.isValid())
            return;

        QXmlFormatter formatter(query, &buffer);
        if (!query.evaluateTo(&formatter))
            return;

        buffer.close();
        findChild<QTextEdit*>("outputTextEdit")->setPlainText(QString::fromUtf8(outArray.constData()));

    }