Qt 5.11 | Qt SQL | Books | bookwindow.cpp Example File

Qt 5.11.3 Reference Documentation

# bookwindow.cpp Example File

books/bookwindow.cpp

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      #include "bookwindow.h"
      #include "bookdelegate.h"
      #include "initdb.h"

      #include <QtSql>

      BookWindow::BookWindow()
      {
          ui.setupUi(this);

          if (!QSqlDatabase::drivers().contains("QSQLITE"))
              QMessageBox::critical(
                          this,
                          "Unable to load database",
                          "This demo needs the SQLITE driver"
                          );

          // Initialize the database:
          QSqlError err = initDb();
          if (err.type() != QSqlError::NoError) {
              showError(err);
              return;
          }

          // Create the data model:
          model = new QSqlRelationalTableModel(ui.bookTable);
          model->setEditStrategy(QSqlTableModel::OnManualSubmit);
          model->setTable("books");

          // Remember the indexes of the columns:
          authorIdx = model->fieldIndex("author");
          genreIdx = model->fieldIndex("genre");

          // Set the relations to the other database tables:
          model->setRelation(authorIdx, QSqlRelation("authors", "id", "name"));
          model->setRelation(genreIdx, QSqlRelation("genres", "id", "name"));

          // Set the localized header captions:
          model->setHeaderData(authorIdx, Qt::Horizontal, tr("Author Name"));
          model->setHeaderData(genreIdx, Qt::Horizontal, tr("Genre"));
          model->setHeaderData(model->fieldIndex("title"),
                               Qt::Horizontal, tr("Title"));
          model->setHeaderData(model->fieldIndex("year"), Qt::Horizontal, tr("Year"));
          model->setHeaderData(model->fieldIndex("rating"),
                               Qt::Horizontal, tr("Rating"));

          // Populate the model:
          if (!model->select()) {
              showError(model->lastError());
              return;
          }

          // Set the model and hide the ID column:
          ui.bookTable->setModel(model);
          ui.bookTable->setItemDelegate(new BookDelegate(ui.bookTable));
          ui.bookTable->setColumnHidden(model->fieldIndex("id"), true);
          ui.bookTable->setSelectionMode(QAbstractItemView::SingleSelection);

          // Initialize the Author combo box:
          ui.authorEdit->setModel(model->relationModel(authorIdx));
          ui.authorEdit->setModelColumn(
                      model->relationModel(authorIdx)->fieldIndex("name"));

          ui.genreEdit->setModel(model->relationModel(genreIdx));
          ui.genreEdit->setModelColumn(
                      model->relationModel(genreIdx)->fieldIndex("name"));

          // Lock and prohibit resizing of the width of the rating column:
          ui.bookTable->horizontalHeader()->setSectionResizeMode(
                      model->fieldIndex("rating"),
                      QHeaderView::ResizeToContents);

          QDataWidgetMapper *mapper = new QDataWidgetMapper(this);
          mapper->setModel(model);
          mapper->setItemDelegate(new BookDelegate(this));
          mapper->addMapping(ui.titleEdit, model->fieldIndex("title"));
          mapper->addMapping(ui.yearEdit, model->fieldIndex("year"));
          mapper->addMapping(ui.authorEdit, authorIdx);
          mapper->addMapping(ui.genreEdit, genreIdx);
          mapper->addMapping(ui.ratingEdit, model->fieldIndex("rating"));

          connect(ui.bookTable->selectionModel(),
                  &QItemSelectionModel::currentRowChanged,
                  mapper,
                  &QDataWidgetMapper::setCurrentModelIndex
                  );

          ui.bookTable->setCurrentIndex(model->index(0, 0));
          createMenuBar();
      }

      void BookWindow::showError(const QSqlError &err)
      {
          QMessageBox::critical(this, "Unable to initialize Database",
                      "Error initializing database: " + err.text());
      }

      void BookWindow::createMenuBar()
      {
          QAction *quitAction = new QAction(tr("&Quit"), this);
          QAction *aboutAction = new QAction(tr("&About"), this);
          QAction *aboutQtAction = new QAction(tr("&About Qt"), this);

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

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

          connect(quitAction, &QAction::triggered, this, &BookWindow::close);
          connect(aboutAction, &QAction::triggered, this, &BookWindow::about);
          connect(aboutQtAction, &QAction::triggered, qApp, &QApplication::aboutQt);
      }

      void BookWindow::about()
      {
          QMessageBox::about(this, tr("About Books"),
                  tr("<p>The <b>Books</b> example shows how to use Qt SQL classes "
                     "with a model/view framework."));
      }