- Qt 5.5
- Qt SQL
- Master Detail Example
- dialog.cpp Example File
- Qt 5.5.1 Reference Documentation

# dialog.cpp Example File

masterdetail/dialog.cpp

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    ** This file is part of the examples of the Qt Toolkit.
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    #include "dialog.h"

    int uniqueAlbumId;
    int uniqueArtistId;

    Dialog::Dialog(QSqlRelationalTableModel *albums, QDomDocument details,
                   QFile *output, QWidget *parent)
         : QDialog(parent)
    {
        model = albums;
        albumDetails = details;
        outputFile = output;

        QGroupBox *inputWidgetBox = createInputWidgets();
        QDialogButtonBox *buttonBox = createButtons();

        QVBoxLayout *layout = new QVBoxLayout;
        layout->addWidget(inputWidgetBox);
        layout->addWidget(buttonBox);
        setLayout(layout);

        setWindowTitle(tr("Add Album"));
    }

    void Dialog::submit()
    {
        QString artist = artistEditor->text();
        QString title = titleEditor->text();

        if (artist.isEmpty() || title.isEmpty()) {
            QString message(tr("Please provide both the name of the artist "
                               "and the title of the album."));
            QMessageBox::information(this, tr("Add Album"), message);
        } else {
            int artistId = findArtistId(artist);
            int albumId = addNewAlbum(title, artistId);

            QStringList tracks;
            tracks = tracksEditor->text().split(',', QString::SkipEmptyParts);
            addTracks(albumId, tracks);

            increaseAlbumCount(indexOfArtist(artist));
            accept();
        }
    }

    int Dialog::findArtistId(const QString &artist)
    {
        QSqlTableModel *artistModel = model->relationModel(2);
        int row = 0;

        while (row < artistModel->rowCount()) {
            QSqlRecord record = artistModel->record(row);
            if (record.value("artist") == artist)
                return record.value("id").toInt();
            else
                row++;
        }
        return addNewArtist(artist);
    }

    int Dialog::addNewArtist(const QString &name)
    {
        QSqlTableModel *artistModel = model->relationModel(2);
        QSqlRecord record;

        int id = generateArtistId();

        QSqlField f1("id", QVariant::Int);
        QSqlField f2("artist", QVariant::String);
        QSqlField f3("albumcount", QVariant::Int);

        f1.setValue(QVariant(id));
        f2.setValue(QVariant(name));
        f3.setValue(QVariant(0));
        record.append(f1);
        record.append(f2);
        record.append(f3);

        artistModel->insertRecord(-1, record);
        return id;
    }

    int Dialog::addNewAlbum(const QString &title, int artistId)
    {
        int id = generateAlbumId();
        QSqlRecord record;

        QSqlField f1("albumid", QVariant::Int);
        QSqlField f2("title", QVariant::String);
        QSqlField f3("artistid", QVariant::Int);
        QSqlField f4("year", QVariant::Int);

        f1.setValue(QVariant(id));
        f2.setValue(QVariant(title));
        f3.setValue(QVariant(artistId));
        f4.setValue(QVariant(yearEditor->value()));
        record.append(f1);
        record.append(f2);
        record.append(f3);
        record.append(f4);

        model->insertRecord(-1, record);
        return id;
    }

    void Dialog::addTracks(int albumId, QStringList tracks)
    {
        QDomElement albumNode = albumDetails.createElement("album");
        albumNode.setAttribute("id", albumId);

        for (int i = 0; i < tracks.count(); i++) {
            QString trackNumber = QString::number(i);
            if (i < 10)
                trackNumber.prepend("0");

            QDomText textNode = albumDetails.createTextNode(tracks.at(i));

            QDomElement trackNode = albumDetails.createElement("track");
            trackNode.setAttribute("number", trackNumber);
            trackNode.appendChild(textNode);

            albumNode.appendChild(trackNode);
        }

        QDomNodeList archive = albumDetails.elementsByTagName("archive");
        archive.item(0).appendChild(albumNode);

    /*
        The following code is commented out since the example uses an in
        memory database, i.e., altering the XML file will bring the data
        out of sync.

        if (!outputFile->open(QIODevice::WriteOnly)) {
            return;
        } else {
            QTextStream stream(outputFile);
            archive.item(0).save(stream, 4);
            outputFile->close();
        }
    */
    }

    void Dialog::increaseAlbumCount(QModelIndex artistIndex)
    {
        QSqlTableModel *artistModel = model->relationModel(2);

        QModelIndex albumCountIndex;
        albumCountIndex = artistIndex.sibling(artistIndex.row(), 2);

        int albumCount = albumCountIndex.data().toInt();
        artistModel->setData(albumCountIndex, QVariant(albumCount + 1));
    }

    void Dialog::revert()
    {
        artistEditor->clear();
        titleEditor->clear();
        yearEditor->setValue(QDate::currentDate().year());
        tracksEditor->clear();
    }

    QGroupBox *Dialog::createInputWidgets()
    {
        QGroupBox *box = new QGroupBox(tr("Add Album"));

        QLabel *artistLabel = new QLabel(tr("Artist:"));
        QLabel *titleLabel = new QLabel(tr("Title:"));
        QLabel *yearLabel = new QLabel(tr("Year:"));
        QLabel *tracksLabel = new QLabel(tr("Tracks (separated by comma):"));

        artistEditor = new QLineEdit;
        titleEditor = new QLineEdit;

        yearEditor = new QSpinBox;
        yearEditor->setMinimum(1900);
        yearEditor->setMaximum(QDate::currentDate().year());
        yearEditor->setValue(yearEditor->maximum());
        yearEditor->setReadOnly(false);

        tracksEditor = new QLineEdit;

        QGridLayout *layout = new QGridLayout;
        layout->addWidget(artistLabel, 0, 0);
        layout->addWidget(artistEditor, 0, 1);
        layout->addWidget(titleLabel, 1, 0);
        layout->addWidget(titleEditor, 1, 1);
        layout->addWidget(yearLabel, 2, 0);
        layout->addWidget(yearEditor, 2, 1);
        layout->addWidget(tracksLabel, 3, 0, 1, 2);
        layout->addWidget(tracksEditor, 4, 0, 1, 2);
        box->setLayout(layout);

        return box;
    }

    QDialogButtonBox *Dialog::createButtons()
    {
        QPushButton *closeButton = new QPushButton(tr("&Close"));
        QPushButton *revertButton = new QPushButton(tr("&Revert"));
        QPushButton *submitButton = new QPushButton(tr("&Submit"));

        closeButton->setDefault(true);

        connect(closeButton, SIGNAL(clicked()), this, SLOT(close()));
        connect(revertButton, SIGNAL(clicked()), this, SLOT(revert()));
        connect(submitButton, SIGNAL(clicked()), this, SLOT(submit()));

        QDialogButtonBox *buttonBox = new QDialogButtonBox;
        buttonBox->addButton(submitButton, QDialogButtonBox::ResetRole);
        buttonBox->addButton(revertButton, QDialogButtonBox::ResetRole);
        buttonBox->addButton(closeButton, QDialogButtonBox::RejectRole);

        return buttonBox;
    }

    QModelIndex Dialog::indexOfArtist(const QString &artist)
    {
        QSqlTableModel *artistModel = model->relationModel(2);

        for (int i = 0; i < artistModel->rowCount(); i++) {
            QSqlRecord record =  artistModel->record(i);
            if (record.value("artist") == artist)
                return artistModel->index(i, 1);
        }

        return QModelIndex();
    }

    int Dialog::generateArtistId()
    {
        uniqueArtistId += 1;
        return uniqueArtistId;
    }

    int Dialog::generateAlbumId()
    {
        uniqueAlbumId += 1;
        return uniqueAlbumId;
    }