- Qt 5.5
- Qt SQL
- Books
- bookwindow.cpp Example File
- Qt 5.5.1 Reference Documentation

# bookwindow.cpp Example File

books/bookwindow.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the demonstration applications of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:LGPL21$
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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());
    }