C++ QSqlTableModel::fetchMore方法代码示例

void CollectionTreeWidget::showChildrenOf(QModelIndex index) {
    CollectionTreeWidgetItem *item = (CollectionTreeWidgetItem*)itemFromIndex(index);

    // If the item pressed was an artist, add albums
    if (item->getNodeLevel() == LevelArtist) {
        QString artist = item->text(0).toUtf8();

        // Looks for artist id
        QString artistId = QString::number(item->getId());

        // Looks for artist albums
        QSqlTableModel *albumModel = service->albumModel();
        albumModel->setFilter("id_artist = " + artistId);
        albumModel->select();

        while (albumModel->canFetchMore()) albumModel->fetchMore();
        int total = albumModel->rowCount();

        for (int i = 0; i < total; i++) {
            QString album = albumModel->record(i).value(albumModel->fieldIndex("title")).toString();
            unsigned int id = albumModel->record(i).value(albumModel->fieldIndex("id")).toInt();
            addAlbum(artist, album, id);
        }

        delete albumModel;
    }
    // If the item pressed was an album, add songs
    else if (item->getNodeLevel() == LevelAlbum) {
        QString albumId = QString::number(item->getId());

        QSqlTableModel *musicModel = service->musicModel();
        musicModel->setFilter("id_album = " + albumId);
        musicModel->setSort(musicModel->fieldIndex("track_number"), Qt::AscendingOrder);
        musicModel->select();

        while (musicModel->canFetchMore()) musicModel->fetchMore();
        int total = musicModel->rowCount();

        for (int i = 0; i < total; i++) {
            QString path = musicModel->record(i).value(musicModel->fieldIndex("path")).toString();
            unsigned int id = musicModel->record(i).value(musicModel->fieldIndex("id")).toInt();

            Music *music = new Music(QUrl(path));
            addMusic(music, id);
            delete music;
        }
    }

    expand(index);
}

void EngineerExam::parseQuestions(QString filename) {
    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName(filename);
    if (!db.open()) {
	qCritical() << trUtf8("Nie można otworzyć bazy danych!");
    }

    QSqlTableModel question;
    question.setTable("Question");
    question.select();

    QSqlTableModel answers;
    answers.setTable("Answer");
    answers.select();

    QStringList qsl;

    int i = 0;
    while (question.canFetchMore()) {
	question.fetchMore();
	for (; i < question.rowCount(); ++i) {
	    qsl.clear();

	    quint32 id = question.record(i).value("Id").toUInt();
	    QString text = question.record(i).value("Text").toString();
	    Question q;
	    q.setId(id);
	    q.setQuestion(text);

	    answers.setFilter(QString("`id_Question` = %1").arg(id));
	    QString a1 = answers.record(0).value("Text").toString();
	    QString a2 = answers.record(1).value("Text").toString();
	    QString a3 = answers.record(2).value("Text").toString();
	    qsl << a1 << a2 << a3;

	    bool correct1 = answers.record(0).value("IsTrue").toBool();
	    bool correct2 = answers.record(1).value("IsTrue").toBool();
	    bool correct3 = answers.record(2).value("IsTrue").toBool();

	    if (correct1) {
		q.setCorrectAnswer(0);
	    } else if (correct2) {
		q.setCorrectAnswer(1);
	    } else if (correct3) {
		q.setCorrectAnswer(2);
	    }
	    q.setAnswers(qsl);
	    tmpList.append(q);
	}
    }
}

QTreeWidgetItem *CollectionTreeWidget::addAlbum(QString artist, QString album, unsigned int albumId) {
    // Find id in database if we don't have it
    if (albumId == 0) {
         QSqlTableModel *model = service->collectionModel();

         // SQLite used two single quotes to escape a single quote! :)
         QString filter = "artist = '" + QString(artist).replace("'","''") + "' AND "
                          "album = '" + QString(album).replace("'","''") + "'";
         model->setFilter(filter);
         model->select();

         while (model->canFetchMore()) model->fetchMore();
         int total = model->rowCount();
         if (total > 0) {
            albumId = model->record(0).value(model->fieldIndex("id_album")).toInt();
         }
         else {
             qDebug("ERROR: no album found! -- " + model->filter().toUtf8());
             return NULL;
         }
    }

    // Looks for the artist
    QTreeWidgetItem *newAlbumNode; // The node with the album, whether it exists or not
    QTreeWidgetItem *artistItem;
    artistItem = addArtist(artist);

    // Look for album
    for (int i = 0; i < artistItem->childCount(); i++) {
        if (artistItem->child(i)->text(0) == album) {
            newAlbumNode = artistItem->child(i);
            return newAlbumNode;
        }
    }

    // Create our new album node and add it if it was not found
    newAlbumNode = new CollectionTreeWidgetItem(LevelAlbum, albumId, (QTreeWidget*)0);
    newAlbumNode->setText(0, album);
    newAlbumNode->setChildIndicatorPolicy(QTreeWidgetItem::ShowIndicator);

    // Set icon
    newAlbumNode->setIcon(0, IconFactory::fromTheme("media-cdrom"));

    artistItem->addChild(newAlbumNode);
    artistItem->sortChildren(0, Qt::AscendingOrder);

    return newAlbumNode;
}

/// @brief Constructor
CollectionTreeWidget::CollectionTreeWidget()
{
    setColumnCount(1);
    header()->hide(); // hide headers
    setDragEnabled(true);
    setAcceptDrops(true);
    setSelectionMode(QAbstractItemView::ExtendedSelection);

    service = new CollectionService();

    // Add songs that currently exist on database
    QSqlTableModel *artistModel = service->artistModel();
    artistModel->select();

    // TODO: verify if we can put fetchmore() inside the for loop.
    // TODO: put this task in background... URGENT
    while (artistModel->canFetchMore()) artistModel->fetchMore();
    int total = artistModel->rowCount();

    for (int i = 0; i < total; i++) {
        QString artist = artistModel->record(i).value(artistModel->fieldIndex("name")).toString();
        unsigned int id = artistModel->record(i).value(artistModel->fieldIndex("id")).toInt();
        addArtist(artist, id);
    }
    delete artistModel;

    /*
     * TODO: modify the slots in order to add only the artist, not the music.
     *       The album and song must be shown only if the node is already expanded.
     */
    connect(service, SIGNAL(songAdded(Music*)), this, SLOT(addMusic(Music*)));
    connect(service, SIGNAL(songRemoved(unsigned int)), this, SLOT(removeMusic(uint)));
    connect(this, SIGNAL(doubleClicked(QModelIndex)), this, SLOT(doubleClickAt(QModelIndex)));
    connect(this, SIGNAL(expanded(QModelIndex)), this, SLOT(showChildrenOf(QModelIndex)));

    /*
     * We shall emit those signals to show or hide the widget that will
     * give the feedback that the collection is being scanned.
     */
    connect(service, SIGNAL(scanning()), this, SIGNAL(scanning()));
    connect(service, SIGNAL(listUpdated()), this, SIGNAL(listUpdated()));

    // Start service to find new songs and remove the inexistent ones
    service->start(QThread::LowestPriority);
}

CollectionTreeWidgetItem *CollectionTreeWidget::addMusic(Music *music, unsigned int id) {
    // Find id in database if we don't have it
    if (id == 0) {
         QSqlTableModel *model = service->collectionModel();

         // SQLite used two single quotes to escape a single quote! :)
         QString filter = "artist = '" + music->getArtist().replace("'","''") + "' AND "
                          "album = '" + music->getAlbum().replace("'","''") + "' AND "
                          "music = '" + music->getTitle().replace("'","''") + "'";
         model->setFilter(filter);
         model->select();

         while (model->canFetchMore()) model->fetchMore();
         int total = model->rowCount();
         if (total > 0) {
            id = model->record(0).value(model->fieldIndex("id_music")).toInt();
         }
         else {
             qDebug("ERROR: no songs found! -- " + model->filter().toUtf8());
             return NULL;
         }
    }

    // Looks for the album
    QTreeWidgetItem *albumItem = addAlbum(music->getArtist(), music->getAlbum());

    // Create our new music node and add it if it was not found
    removeMusic(id);

    CollectionTreeWidgetItem *newMusicNode = new CollectionTreeWidgetItem(LevelMusic, id, (QTreeWidget*)0);
    newMusicNode->setText(0, music->getTitle());
    newMusicNode->setIcon(0, IconFactory::fromTheme("sound"));
    albumItem->addChild(newMusicNode);
    musicList.append(newMusicNode);

    return newMusicNode;
}