- Qt 5.5
- Qt SQL
- SQL Widget Mapper Example
- window.cpp Example File
- Qt 5.5.1 Reference Documentation

# window.cpp Example File

sqlwidgetmapper/window.cpp

    /****************************************************************************
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    ** This file is part of the examples of the Qt Toolkit.
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    #include <QtWidgets>
    #include <QtSql>

    #include "window.h"

    Window::Window(QWidget *parent)
        : QWidget(parent)
    {
        setupModel();

        nameLabel = new QLabel(tr("Na&me:"));
        nameEdit = new QLineEdit();
        addressLabel = new QLabel(tr("&Address:"));
        addressEdit = new QTextEdit();
        typeLabel = new QLabel(tr("&Type:"));
        typeComboBox = new QComboBox();
        nextButton = new QPushButton(tr("&Next"));
        previousButton = new QPushButton(tr("&Previous"));

        nameLabel->setBuddy(nameEdit);
        addressLabel->setBuddy(addressEdit);
        typeLabel->setBuddy(typeComboBox);

        QSqlTableModel *relModel = model->relationModel(typeIndex);
        typeComboBox->setModel(relModel);
        typeComboBox->setModelColumn(relModel->fieldIndex("description"));

        mapper = new QDataWidgetMapper(this);
        mapper->setModel(model);
        mapper->setItemDelegate(new QSqlRelationalDelegate(this));
        mapper->addMapping(nameEdit, model->fieldIndex("name"));
        mapper->addMapping(addressEdit, model->fieldIndex("address"));
        mapper->addMapping(typeComboBox, typeIndex);

        connect(previousButton, SIGNAL(clicked()),
                mapper, SLOT(toPrevious()));
        connect(nextButton, SIGNAL(clicked()),
                mapper, SLOT(toNext()));
        connect(mapper, SIGNAL(currentIndexChanged(int)),
                this, SLOT(updateButtons(int)));

        QGridLayout *layout = new QGridLayout();
        layout->addWidget(nameLabel, 0, 0, 1, 1);
        layout->addWidget(nameEdit, 0, 1, 1, 1);
        layout->addWidget(previousButton, 0, 2, 1, 1);
        layout->addWidget(addressLabel, 1, 0, 1, 1);
        layout->addWidget(addressEdit, 1, 1, 2, 1);
        layout->addWidget(nextButton, 1, 2, 1, 1);
        layout->addWidget(typeLabel, 3, 0, 1, 1);
        layout->addWidget(typeComboBox, 3, 1, 1, 1);
        setLayout(layout);

        setWindowTitle(tr("SQL Widget Mapper"));
        mapper->toFirst();
    }

    void Window::setupModel()
    {
        QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
        db.setDatabaseName(":memory:");
        if (!db.open()) {
            QMessageBox::critical(0, tr("Cannot open database"),
                tr("Unable to establish a database connection.\n"
                   "This example needs SQLite support. Please read "
                   "the Qt SQL driver documentation for information how "
                   "to build it."), QMessageBox::Cancel);
            return;
        }

        QSqlQuery query;
        query.exec("create table person (id int primary key, "
                   "name varchar(20), address varchar(200), typeid int)");
        query.exec("insert into person values(1, 'Alice', "
                   "'<qt>123 Main Street<br/>Market Town</qt>', 101)");
        query.exec("insert into person values(2, 'Bob', "
                   "'<qt>PO Box 32<br/>Mail Handling Service"
                   "<br/>Service City</qt>', 102)");
        query.exec("insert into person values(3, 'Carol', "
                   "'<qt>The Lighthouse<br/>Remote Island</qt>', 103)");
        query.exec("insert into person values(4, 'Donald', "
                   "'<qt>47338 Park Avenue<br/>Big City</qt>', 101)");
        query.exec("insert into person values(5, 'Emma', "
                   "'<qt>Research Station<br/>Base Camp<br/>"
                   "Big Mountain</qt>', 103)");

        query.exec("create table addresstype (id int, description varchar(20))");
        query.exec("insert into addresstype values(101, 'Home')");
        query.exec("insert into addresstype values(102, 'Work')");
        query.exec("insert into addresstype values(103, 'Other')");

        model = new QSqlRelationalTableModel(this);
        model->setTable("person");
        model->setEditStrategy(QSqlTableModel::OnManualSubmit);

        typeIndex = model->fieldIndex("typeid");

        model->setRelation(typeIndex,
               QSqlRelation("addresstype", "id", "description"));
        model->select();
    }

    void Window::updateButtons(int row)
    {
        previousButton->setEnabled(row > 0);
        nextButton->setEnabled(row < model->rowCount() - 1);
    }