Qt 5.9 | Qt SQL | Master Detail Example | mainwindow.cpp Example File

Qt 5.9.9 Reference Documentation

# mainwindow.cpp Example File

masterdetail/mainwindow.cpp

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      #include "mainwindow.h"
      #include "dialog.h"

      #include <QtWidgets>
      #include <QtSql>
      #include <QtXml>

      extern int uniqueAlbumId;
      extern int uniqueArtistId;

      MainWindow::MainWindow(const QString &artistTable, const QString &albumTable,
                             QFile *albumDetails, QWidget *parent)
           : QMainWindow(parent)
      {
          file = albumDetails;
          readAlbumData();

          model = new QSqlRelationalTableModel(this);
          model->setTable(albumTable);
          model->setRelation(2, QSqlRelation(artistTable, "id", "artist"));
          model->select();

          QGroupBox *artists = createArtistGroupBox();
          QGroupBox *albums = createAlbumGroupBox();
          QGroupBox *details = createDetailsGroupBox();

          artistView->setCurrentIndex(0);
          uniqueAlbumId = model->rowCount();
          uniqueArtistId = artistView->count();

          connect(model, &QSqlRelationalTableModel::rowsInserted,
                  this, &MainWindow::updateHeader);
          connect(model, &QSqlRelationalTableModel::rowsRemoved,
                  this, &MainWindow::updateHeader);

          QGridLayout *layout = new QGridLayout;
          layout->addWidget(artists, 0, 0);
          layout->addWidget(albums, 1, 0);
          layout->addWidget(details, 0, 1, 2, 1);
          layout->setColumnStretch(1, 1);
          layout->setColumnMinimumWidth(0, 500);

          QWidget *widget = new QWidget;
          widget->setLayout(layout);
          setCentralWidget(widget);
          createMenuBar();

          showImageLabel();
          resize(850, 400);
          setWindowTitle(tr("Music Archive"));
      }

      void MainWindow::changeArtist(int row)
      {
          if (row > 0) {
              QModelIndex index = model->relationModel(2)->index(row, 1);
              model->setFilter("artist = '" + index.data().toString() + '\'') ;
              showArtistProfile(index);
          } else if (row == 0) {
              model->setFilter(QString());
              showImageLabel();
          } else {
              return;
          }
      }

      void MainWindow::showArtistProfile(QModelIndex index)
      {
          QSqlRecord record = model->relationModel(2)->record(index.row());

          QString name = record.value("artist").toString();
          QString count = record.value("albumcount").toString();
          profileLabel->setText(tr("Artist : %1 \n" \
                                   "Number of Albums: %2").arg(name).arg(count));

          profileLabel->show();
          iconLabel->show();

          titleLabel->hide();
          trackList->hide();
          imageLabel->hide();
      }

      void MainWindow::showAlbumDetails(QModelIndex index)
      {
          QSqlRecord record = model->record(index.row());

          QString artist = record.value("artist").toString();
          QString title = record.value("title").toString();
          QString year = record.value("year").toString();
          QString albumId = record.value("albumid").toString();

          showArtistProfile(indexOfArtist(artist));
          titleLabel->setText(tr("Title: %1 (%2)").arg(title).arg(year));
          titleLabel->show();

          QDomNodeList albums = albumData.elementsByTagName("album");
          for (int i = 0; i < albums.count(); ++i) {
              QDomNode album = albums.item(i);
              if (album.toElement().attribute("id") == albumId) {
                  getTrackList(album.toElement());
                  break;
              }
          }
          if (trackList->count() != 0)
              trackList->show();
      }

      void MainWindow::getTrackList(QDomNode album)
      {
          trackList->clear();

          QDomNodeList tracks = album.childNodes();
          QDomNode track;
          QString trackNumber;

          for (int i = 0; i < tracks.count(); ++i) {

              track = tracks.item(i);
              trackNumber = track.toElement().attribute("number");

              QListWidgetItem *item = new QListWidgetItem(trackList);
              item->setText(trackNumber + ": " + track.toElement().text());
          }
      }

      void MainWindow::addAlbum()
      {
          Dialog *dialog = new Dialog(model, albumData, file, this);
          int accepted = dialog->exec();

          if (accepted == 1) {
              int lastRow = model->rowCount() - 1;
              albumView->selectRow(lastRow);
              albumView->scrollToBottom();
              showAlbumDetails(model->index(lastRow, 0));
          }
      }

      void MainWindow::deleteAlbum()
      {
          QModelIndexList selection = albumView->selectionModel()->selectedRows(0);

          if (!selection.empty()) {
              QModelIndex idIndex = selection.at(0);
              int id = idIndex.data().toInt();
              QString title = idIndex.sibling(idIndex.row(), 1).data().toString();
              QString artist = idIndex.sibling(idIndex.row(), 2).data().toString();

              QMessageBox::StandardButton button;
              button = QMessageBox::question(this, tr("Delete Album"),
                                             tr("Are you sure you want to "
                                                "delete '%1' by '%2'?")
                                             .arg(title, artist),
                                             QMessageBox::Yes | QMessageBox::No);

              if (button == QMessageBox::Yes) {
                  removeAlbumFromFile(id);
                  removeAlbumFromDatabase(idIndex);
                  decreaseAlbumCount(indexOfArtist(artist));

                  showImageLabel();
              }
          } else {
              QMessageBox::information(this, tr("Delete Album"),
                                       tr("Select the album you want to delete."));
          }
      }

      void MainWindow::removeAlbumFromFile(int id)
      {

          QDomNodeList albums = albumData.elementsByTagName("album");

          for (int i = 0; i < albums.count(); ++i) {
              QDomNode node = albums.item(i);
              if (node.toElement().attribute("id").toInt() == id) {
                  albumData.elementsByTagName("archive").item(0).removeChild(node);
                  break;
              }
          }
      /*
          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 (!file->open(QIODevice::WriteOnly)) {
              return;
          } else {
              QTextStream stream(file);
              albumData.elementsByTagName("archive").item(0).save(stream, 4);
              file->close();
          }
      */
      }

      void MainWindow::removeAlbumFromDatabase(QModelIndex index)
      {
          model->removeRow(index.row());
      }

      void MainWindow::decreaseAlbumCount(QModelIndex artistIndex)
      {
          int row = artistIndex.row();
          QModelIndex albumCountIndex = artistIndex.sibling(row, 2);
          int albumCount = albumCountIndex.data().toInt();

          QSqlTableModel *artists = model->relationModel(2);

          if (albumCount == 1) {
              artists->removeRow(row);
              showImageLabel();
          } else {
              artists->setData(albumCountIndex, QVariant(albumCount - 1));
          }
      }

      void MainWindow::readAlbumData()
      {
          if (!file->open(QIODevice::ReadOnly))
              return;

          if (!albumData.setContent(file)) {
              file->close();
              return;
          }
          file->close();
      }

      QGroupBox* MainWindow::createArtistGroupBox()
      {
          artistView = new QComboBox;
          artistView->setModel(model->relationModel(2));
          artistView->setModelColumn(1);

          connect(artistView, QOverload<int>::of(&QComboBox::currentIndexChanged),
                  this, &MainWindow::changeArtist);

          QGroupBox *box = new QGroupBox(tr("Artist"));

          QGridLayout *layout = new QGridLayout;
          layout->addWidget(artistView, 0, 0);
          box->setLayout(layout);

          return box;
      }

      QGroupBox* MainWindow::createAlbumGroupBox()
      {
          QGroupBox *box = new QGroupBox(tr("Album"));

          albumView = new QTableView;
          albumView->setEditTriggers(QAbstractItemView::NoEditTriggers);
          albumView->setSortingEnabled(true);
          albumView->setSelectionBehavior(QAbstractItemView::SelectRows);
          albumView->setSelectionMode(QAbstractItemView::SingleSelection);
          albumView->setShowGrid(false);
          albumView->verticalHeader()->hide();
          albumView->setAlternatingRowColors(true);
          albumView->setModel(model);
          adjustHeader();

          QLocale locale = albumView->locale();
          locale.setNumberOptions(QLocale::OmitGroupSeparator);
          albumView->setLocale(locale);

          connect(albumView, &QTableView::clicked,
                  this, &MainWindow::showAlbumDetails);
          connect(albumView, &QTableView::activated,
                  this, &MainWindow::showAlbumDetails);

          QVBoxLayout *layout = new QVBoxLayout;
          layout->addWidget(albumView, 0, 0);
          box->setLayout(layout);

          return box;
      }

      QGroupBox* MainWindow::createDetailsGroupBox()
      {
          QGroupBox *box = new QGroupBox(tr("Details"));

          profileLabel = new QLabel;
          profileLabel->setWordWrap(true);
          profileLabel->setAlignment(Qt::AlignBottom);

          titleLabel = new QLabel;
          titleLabel->setWordWrap(true);
          titleLabel->setAlignment(Qt::AlignBottom);

          iconLabel = new QLabel();
          iconLabel->setAlignment(Qt::AlignBottom | Qt::AlignRight);
          iconLabel->setPixmap(QPixmap(":/images/icon.png"));

          imageLabel = new QLabel;
          imageLabel->setWordWrap(true);
          imageLabel->setAlignment(Qt::AlignCenter);
          imageLabel->setPixmap(QPixmap(":/images/image.png"));

          trackList = new QListWidget;

          QGridLayout *layout = new QGridLayout;
          layout->addWidget(imageLabel, 0, 0, 3, 2);
          layout->addWidget(profileLabel, 0, 0);
          layout->addWidget(iconLabel, 0, 1);
          layout->addWidget(titleLabel, 1, 0, 1, 2);
          layout->addWidget(trackList, 2, 0, 1, 2);
          layout->setRowStretch(2, 1);
          box->setLayout(layout);

          return box;
      }

      void MainWindow::createMenuBar()
      {
          QAction *addAction = new QAction(tr("&Add album..."), this);
          QAction *deleteAction = new QAction(tr("&Delete album..."), this);
          QAction *quitAction = new QAction(tr("&Quit"), this);
          QAction *aboutAction = new QAction(tr("&About"), this);
          QAction *aboutQtAction = new QAction(tr("About &Qt"), this);

          addAction->setShortcut(tr("Ctrl+A"));
          deleteAction->setShortcut(tr("Ctrl+D"));
          quitAction->setShortcuts(QKeySequence::Quit);

          QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
          fileMenu->addAction(addAction);
          fileMenu->addAction(deleteAction);
          fileMenu->addSeparator();
          fileMenu->addAction(quitAction);

          QMenu *helpMenu = menuBar()->addMenu(tr("&Help"));
          helpMenu->addAction(aboutAction);
          helpMenu->addAction(aboutQtAction);

          connect(addAction, &QAction::triggered,
                  this, &MainWindow::addAlbum);
          connect(deleteAction, &QAction::triggered,
                  this, &MainWindow::deleteAlbum);
          connect(quitAction, &QAction::triggered,
                  this, &MainWindow::close);
          connect(aboutAction, &QAction::triggered,
                  this, &MainWindow::about);
          connect(aboutQtAction, &QAction::triggered,
                  qApp, &QApplication::aboutQt);
      }

      void MainWindow::showImageLabel()
      {
          profileLabel->hide();
          titleLabel->hide();
          iconLabel->hide();
          trackList->hide();

          imageLabel->show();
      }

      QModelIndex MainWindow::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();
      }

      void MainWindow::updateHeader(QModelIndex, int, int)
      {
          adjustHeader();
      }

      void MainWindow::adjustHeader()
      {
          albumView->hideColumn(0);
          albumView->horizontalHeader()->setSectionResizeMode(1, QHeaderView::Stretch);
          albumView->resizeColumnToContents(2);
          albumView->resizeColumnToContents(3);
      }

      void MainWindow::about()
      {
          QMessageBox::about(this, tr("About Music Archive"),
                  tr("<p>The <b>Music Archive</b> example shows how to present "
                     "data from different data sources in the same application. "
                     "The album titles, and the corresponding artists and release dates, "
                     "are kept in a database, while each album's tracks are stored "
                     "in an XML file. </p><p>The example also shows how to add as "
                     "well as remove data from both the database and the "
                     "associated XML file using the API provided by the Qt SQL and "
                     "Qt XML modules, respectively.</p>"));
      }