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==Data mapper==

<source lang="cpp">
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef WINDOW_H
#define WINDOW_H
#include <QWidget>
QT_BEGIN_NAMESPACE
class QComboBox;
class QDataWidgetMapper;
class QItemSelectionModel;
class QLabel;
class QLineEdit;
class QPushButton;
class QSqlRelationalTableModel;
class QStandardItemModel;
class QStringListModel;
class QTextEdit;
QT_END_NAMESPACE
//! [Window definition]
class Window : public QWidget
{
Q_OBJECT
public:
Window(QWidget *parent = 0);
private slots:
void updateButtons(int row);
private:
void setupModel();
QLabel *nameLabel;
QLabel *addressLabel;
QLabel *typeLabel;
QLineEdit *nameEdit;
QTextEdit *addressEdit;
QComboBox *typeComboBox;
QPushButton *nextButton;
QPushButton *previousButton;
QSqlRelationalTableModel *model;
QItemSelectionModel *selectionModel;
QDataWidgetMapper *mapper;
int typeIndex;
};
//! [Window definition]
#endif

#include <QtGui>
#include <QtSql>
#include "window.h"
//! [Set up widgets]
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);
//! [Set up widgets]
//! [Set up the mapper]
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);
//! [Set up the mapper]
//! [Set up connections and layouts]
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();
}
//! [Set up connections and layouts]
//! [Set up the main table]
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 Market Town</qt>", 101)");
query.exec("insert into person values(2, "Bob", "
""<qt>PO Box 32 Mail Handling Service"
" Service City</qt>", 102)");
query.exec("insert into person values(3, "Carol", "
""<qt>The Lighthouse Remote Island</qt>", 103)");
query.exec("insert into person values(4, "Donald", "
""<qt>47338 Park Avenue Big City</qt>", 101)");
query.exec("insert into person values(5, "Emma", "
""<qt>Research Station Base Camp "
"Big Mountain</qt>", 103)");
//! [Set up the main table]
//! [Set up the address type table]
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();
}
//! [Set up the address type table]
//! [Slot for updating the buttons]
void Window::updateButtons(int row)
{
previousButton->setEnabled(row > 0);
nextButton->setEnabled(row < model->rowCount() - 1);
}
//! [Slot for updating the buttons]

#include <QApplication>
#include "window.h"
int main(int argc, char **argv)
{
QApplication app(argc, argv);
Window window;
window.show();
return app.exec();
}

</source>

==Using QSqlRelationalTableModel==

<source lang="cpp">
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef CONNECTION_H
#define CONNECTION_H
#include <QMessageBox>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlQuery>
/*
This file defines a helper function to open a connection to an
in-memory SQLITE database and to create a test table.
If you want to use another database, simply modify the code
below. All the examples in this directory use this function to
connect to a database.
*/
static bool createConnection()
{
QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName(":memory:");
if (!db.open()) {
QMessageBox::critical(0, qApp->tr("Cannot open database"),
qApp->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.\n\n"
"Click Cancel to exit."), QMessageBox::Cancel);
return false;
}
QSqlQuery query;
query.exec("create table person (id int primary key, "
"firstname varchar(20), lastname varchar(20))");
query.exec("insert into person values(101, "Danny", "Young")");
query.exec("insert into person values(102, "Christine", "Holand")");
query.exec("insert into person values(103, "Lars", "Gordon")");
query.exec("insert into person values(104, "Roberto", "Robitaille")");
query.exec("insert into person values(105, "Maria", "Papadopoulos")");
query.exec("create table offices (id int primary key,"
"imagefile int,"
"location varchar(20),"
"country varchar(20),"
"description varchar(100))");
query.exec("insert into offices "
"values(0, 0, "Oslo", "Norway","
""Oslo is home to more than 500 000 citizens and has a "
"lot to offer.It has been called \"The city with the big "
"heart\" and this is a nickname we are happy to live up to.")");
query.exec("insert into offices "
"values(1, 1, "Brisbane", "Australia","
""Brisbane is the capital of Queensland, the Sunshine State, "
"where it is beautiful one day, perfect the next. "
"Brisbane is Australia""s 3rd largest city, being home "
"to almost 2 million people.")");
query.exec("insert into offices "
"values(2, 2, "Redwood City", "US","
""You find Redwood City in the heart of the Bay Area "
"just north of Silicon Valley. The largest nearby city is "
"San Jose which is the third largest city in California "
"and the 10th largest in the US.")");
query.exec("insert into offices "
"values(3, 3, "Berlin", "Germany","
""Berlin, the capital of Germany is dynamic, cosmopolitan "
"and creative, allowing for every kind of lifestyle. "
"East meets West in the metropolis at the heart of a "
"changing Europe.")");
query.exec("insert into offices "
"values(4, 4, "Munich", "Germany","
""Several technology companies are represented in Munich, "
"and the city is often called the \"Bavarian Silicon Valley\". "
"The exciting city is also filled with culture, "
"art and music. ")");
query.exec("insert into offices "
"values(5, 5, "Beijing", "China","
""Beijing as a capital city has more than 3000 years of "
"history. Today the city counts 12 million citizens, and "
"is the political, economic and cultural centre of China.")");
query.exec("create table images (locationid int, file varchar(20))");
query.exec("insert into images values(0, "images/oslo.png")");
query.exec("insert into images values(1, "images/brisbane.png")");
query.exec("insert into images values(2, "images/redwood.png")");
query.exec("insert into images values(3, "images/berlin.png")");
query.exec("insert into images values(4, "images/munich.png")");
query.exec("insert into images values(5, "images/beijing.png")");

return true;
}

#endif

#include <QtGui>
#include <QtSql>
#include "../connection.h"
void initializeModel(QSqlRelationalTableModel *model)
{
model->setTable("employee");

model->setEditStrategy(QSqlTableModel::OnManualSubmit);
model->setRelation(2, QSqlRelation("city", "id", "name"));

model->setRelation(3, QSqlRelation("country", "id", "name"));

model->setHeaderData(0, Qt::Horizontal, QObject::tr("ID"));
model->setHeaderData(1, Qt::Horizontal, QObject::tr("Name"));
model->setHeaderData(2, Qt::Horizontal, QObject::tr("City"));
model->setHeaderData(3, Qt::Horizontal, QObject::tr("Country"));

model->select();
}
QTableView *createView(const QString &title, QSqlTableModel *model)
{
QTableView *view = new QTableView;
view->setModel(model);
view->setItemDelegate(new QSqlRelationalDelegate(view));
view->setWindowTitle(title);
return view;
}
void createRelationalTables()
{
QSqlQuery query;
query.exec("create table employee(id int primary key, name varchar(20), city int, country int)");
query.exec("insert into employee values(1, "Espen", 5000, 47)");
query.exec("insert into employee values(2, "Harald", 80000, 49)");
query.exec("insert into employee values(3, "Sam", 100, 1)");
query.exec("create table city(id int, name varchar(20))");
query.exec("insert into city values(100, "San Jose")");
query.exec("insert into city values(5000, "Oslo")");
query.exec("insert into city values(80000, "Munich")");
query.exec("create table country(id int, name varchar(20))");
query.exec("insert into country values(1, "USA")");
query.exec("insert into country values(47, "Norway")");
query.exec("insert into country values(49, "Germany")");
}
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
if (!createConnection())
return 1;
createRelationalTables();
QSqlRelationalTableModel model;
initializeModel(&model);
QTableView *view = createView(QObject::tr("Relational Table Model"), &model);
view->show();
return app.exec();
}

</source>

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