Qt 5.6 | Qt SQL | Books | bookwindow.cpp Example File

Qt 5.6.2 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"));

          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(), SIGNAL(currentRowChanged(QModelIndex,QModelIndex)),
                  mapper, SLOT(setCurrentModelIndex(QModelIndex)));

          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());
      }