bookwindow.cpp Example File
^{demos/books/bookwindow.cpp}

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    **
    ** This file is part of the documentation of the Qt Toolkit.
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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");

        // Remeber 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);

        // 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"));

        connect(model, SIGNAL(dataChanged(QModelIndex,QModelIndex)),
                this, SLOT(dataChanged(QModelIndex)));
        connect(ui.bookTable->selectionModel(), SIGNAL(currentRowChanged(QModelIndex,QModelIndex)),
                this, SLOT(currentBookChanged(QModelIndex)));
    }

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

    void BookWindow::currentBookChanged(const QModelIndex &index)
    {
        bool enabled = index.isValid();
        ui.titleEdit->setEnabled(enabled);
        ui.yearEdit->setEnabled(enabled);
        ui.authorEdit->setEnabled(enabled);
        ui.genreEdit->setEnabled(enabled);
        ui.ratingEdit->setEnabled(enabled);

        QSqlRecord rec = model->record(index.row());
        ui.titleEdit->setText(rec.value("title").toString());
        ui.yearEdit->setValue(rec.value("year").toInt());
        ui.authorEdit->setCurrentIndex(ui.authorEdit->findText(
                    model->data(model->index(index.row(), authorIdx)).toString()));
        ui.genreEdit->setCurrentIndex(ui.genreEdit->findText(
                    model->data(model->index(index.row(), genreIdx)).toString()));
        ui.ratingEdit->setCurrentIndex(rec.value("rating").toInt());
    }

    void BookWindow::on_authorEdit_activated(const QString &text)
    {
        QModelIndex currentIndex = model->index(ui.bookTable->currentIndex().row(), authorIdx);
        if (model->data(currentIndex).toString() != text)
            ui.bookTable->itemDelegate()->setModelData(ui.authorEdit, model, currentIndex);
    }

    void BookWindow::on_genreEdit_activated(const QString &text)
    {
        QModelIndex currentIndex = model->index(ui.bookTable->currentIndex().row(), genreIdx);
        if (model->data(currentIndex).toString() != text)
            ui.bookTable->itemDelegate()->setModelData(ui.genreEdit, model, currentIndex);
    }

    void BookWindow::on_ratingEdit_activated(int value)
    {
        QModelIndex currentIndex = model->index(ui.bookTable->currentIndex().row(),
                model->fieldIndex("rating"));
        if (model->data(currentIndex).toInt() != value)
            model->setData(currentIndex, value);
    }

    void BookWindow::on_titleEdit_textChanged(const QString &text)
    {
        QModelIndex currentIndex = model->index(ui.bookTable->currentIndex().row(),
                model->fieldIndex("title"));
        if (model->data(currentIndex).toString() != text)
            model->setData(currentIndex, text);
    }

    void BookWindow::on_yearEdit_valueChanged(int value)
    {
        QModelIndex currentIndex = model->index(ui.bookTable->currentIndex().row(),
                model->fieldIndex("year"));
        if (model->data(currentIndex).toInt() != value)
            model->setData(currentIndex, value);
    }

    void BookWindow::dataChanged(const QModelIndex &index)
    {
        if (index.row() == ui.bookTable->currentIndex().row())
            currentBookChanged(index);
    }