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"));

    // 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."));
}