bookwindow.cpp Example File

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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"));

      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));
  }

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